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The trajectory design is a key factor affecting the frictional resistance of the deflector, which is crucial for the drilling ability of the hydraulic radial drilling system. In this research, the trajectory design model and geometric constraints model of a deflector are established by analyzing the geometric relationship of the deflector and considering the geometric constraints of the casing. According to the actual contact form between the high-pressure hose and the deflector, the theoretical model of frictional resistance is built based on segmental rigidization and micro-element methods. The theoretical model is verified by the deflector friction experiment. The results demonstrate a good agreement between the experimental results of friction resistance of different sizes of high-pressure hoses and the theoretical results, with an error of less than 7%. The influence of critical parameters of deflector trajectory on the friction resistance is studied by coupling the geometric constraints model and the frictional resistance theoretical model of the deflector. The findings show that the deflector's frictional resistance increases with the inclination angle β of the inclined-straight section and decreases with the increase in the radius R of the bending segment, the inclination angle ω of the straightening segment, and the channel radius of r deflector. A new trajectory parameters of the deflector are presented by taking a five-inch casing as an example, they are β = 9°, R = 92 mm, ω = 108°, r = 17 mm. The research results provide a theoretical rationale for designing a low-frictional resistance deflector. [ABSTRACT FROM AUTHOR]

The drag-type Savonius rotor, a type of vertical-axis wind turbine, is designed to capture wind energy and convert it into rotational torque. However, their efficiency is limited, which restricts their commercial viability. This inefficiency is primarily due to the negative torque produced by the returning blades, which results in minimal power output. This study examines the effect of the aspect ratio on a new elliptic-shaped deflector using three-dimensional (3D) computational fluid dynamics (CFD) modeling and an optimization approach. The aim of this novel deflector is to enhance the aerodynamic performance of the Savonius turbine by reducing negative torque during blade sweeping on the return side. Although there is extensive literature on elliptic-shaped bodies, there is a notable lack of research on the interaction between airflow over such a body used as a deflector and the Savonius rotor. This research uses an optimization methodology based on the design of experiments to determine the optimal design. Using the Taguchi method and analysis of variance, the number of blades is identified as the most significant factor, accounting for 77% of the rotor performance near the deflector. At a Tip Speed Ratio (λ) of 0.8, the optimal deflector achieves the highest average power coefficient of 0.34, representing a significant 42% improvement compared to the maximum average power coefficient without a deflector. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Engineering for Thermal Energy & Power / Reneng Dongli Gongcheng is the property of Journal of Engineering for Thermal Energy & Power and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to improve the flow and heat transfer performance of cold channels in turbine blades, the effects of the structure, arrangement form and geometric dimensioning of the deflector on the flow resistance and heat transfer performance in the constricted and expanded serpentine channel at the inlet Reynolds number of 2 × 10 4 ~ 8 × 10 4 were investigated by numerical simulation, and the relationship between secondary flow intensity and thermal performance factor was obtained. The results show that with the increase of Reynolds number, the change range of drag coefficient of the channel with deflector is less than 5%. The 180° deflector has the strongest drag reduction ability among all models, and the drag coefficient of the channel with deflector decreases by 50. 2% compared with that without deflector. The deflector structure plays an enhanced role in heat transfer, the 180° deflector has the most significant enhanced heat transfer effect, increasing the heat transfer coefficient by 12. 3%. Different structures of the deflector have a great influence on the thermal performance factor of the channel, and the thermal performance factor of the 180° deflector channel is the strongest, which is 56. 4% higher than that of the channel without deflector. In summary, the study of the structural parameters of the deflector can effectively reduce the flow resistance loss of the cold channel and enhance its heat transfer capacity. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Central South University is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This article aims to address the issues of low cultivation density and high labor intensity of manual water exchange in existing scallop seedling ponds, an upwelling recirculating water system for scallop larval cultivation is designed. EDEM-Fluent coupled modelwas used to simulate themovement of scallop larvae in the culture cone in order to guarantee the uniform distribution of larvae in the cultivation device. Design-Expert software was utilized to investigate the impact of the bottom cone angle(θ), the column height/cone height ratio(n) and the inflow velocity(v) on the variation coefficients of the axial and radial distributions of D-shaped larvae within the culture cone. The results indicated that θ = 108.97° and n = 1.8 represent the ideal structural parameters for the culture cone. The further investigation of the culture cones prototype was conducted to examine the impact of the inlet deflector angle (α), cultivation density (τ), and inflow velocity (v) on its performance. θ=108.97°, n=1.8, v=0.19m/s, α=60.94°, and τ=110pcs/ml were found to be the ideal combination of parameters, in this scenario, the D-shaped larvae's radial distributions' coefficients of variation is 22.13%, the error between the experimental and simulation results is 4.41%. Research has shown that EDEMFluent based simulation analysis methods can be used for the design and parameter optimization of upwelling recirculating water scallop larval cultivation system, this paper can provide a reference for the design of an upwelling recirculating water scallop larval cultivation system. [ABSTRACT FROM AUTHOR]

Flip bucket is a type of energy dissipator structure. Flip buckets can sometimes be improved by adding wedge-shaped deflectors. This research introduced the best height proportion of used deflector on the flip buckets to increase energy dissipation. It used 4 types of deflector series including 32, 45, 47 and 55 degrees toward horizon with two different regular and irregular layouts and 19 different heights from 2.31 to 5.6 cm and in different hydraulic condition and the results were compared with a flip bucket without a deflector. The characteristics of laboratory flume were: length= 7.5 m, width= 0.58 m and height= 1.6 m. The results illustrates that the energy dissipation in the model with deflectors increased from 11.83 to 19.38 percent as compared with model without a deflector. The greatest percentage of energy dissipation was 80.74% which observed at a deflector angle of 55° and a discharge of 10 L/s, at deflector’s ratio of n=0.8 and in non-uniform layout and in free hydraulic jump. Larger deflector angles and side lengths initially boosted energy dissipation, but this effect plateaued or even reversed at very large angles. For calculating energy dissipation and hydraulic jump length parameters, the regression relations were extracted in this research and results of this relations were compared with results of the gene expression programming (GEP), random forest (RF) and multivariate adaptive regression splines (MARS) methods. The results showed that the RF method is the most accurate method for calculating energy dissipation and hydraulic jump length parameters. [ABSTRACT FROM AUTHOR]

Acousto-optic terahertz radiation deflectors based on an optically isotropic medium are characterized by a low number of resolved light spots. A significant improvement in the deflector characteristics can be achieved by using a sectioned phased ultrasound transducer. The angular–frequency dependence for such a deflector is analytically obtained for the first time and the position of the operating point on it is specified taking into account the influence of the gap between the sections of the ultrasound transducer. [ABSTRACT FROM AUTHOR]

Reflective LCDs have a great advantage of low power consumption, but the brightness is not consistently sufficient because ambient light is used as a light source. To increase light efficiency, we combined reflective LCDs and the Pancharatnam‐Berry deflector (PBD), a diffractive optical element that controls the propagation of incident light. We confirmed that on‐axis brightness is increased by 2.2 times against the incident collimated light from a polar angle of 30° when compared to a reflective LCD without PBD. [ABSTRACT FROM AUTHOR]

Flip bucket is a type of energy dissipator structure. Flip buckets can sometimes be improved by adding wedge-shaped deflectors. This research introduced the best height proportion of used deflector on the flip buckets to increase energy dissipation. It used 4 types of deflector series including 32, 45, 47 and 55 degrees toward horizon with two different regular and irregular layouts and 19 different heights from 2.31 to 5.6 cm and in different hydraulic condition and the results were compared with a flip bucket without a deflector. The characteristics of laboratory flume were: length= 7.5 m, width= 0.58 m and height= 1.6 m. The results illustrates that the energy dissipation in the model with deflectors increased from 11.83 to 19.38 percent as compared with model without a deflector. The greatest percentage of energy dissipation was 80.74% which observed at a deflector angle of 55° and a discharge of 10 L/s, at deflector’s ratio of n=0.8 and in non-uniform layout and in free hydraulic jump. Larger deflector angles and side lengths initially boosted energy dissipation, but this effect plateaued or even reversed at very large angles. For calculating energy dissipation and hydraulic jump length parameters, the regression relations were extracted in this research and results of this relations were compared with results of the gene expression programming (GEP), random forest (RF) and multivariate adaptive regression splines (MARS) methods. The results showed that the RF method is the most accurate method for calculating energy dissipation and hydraulic jump length parameters.

In Europe, the routes of most watercourses were straightened and shortened, leading to the destruction and degradation of many natural environments. Currently, in places where it is possible, as part of the implementation of the Water Framework Directive, efforts are made to improve environmental sustainability, including improving the ecological condition of rivers. This paper presents the impact of three in-stream deflectors on changes in the section of a small lowland river—the Flinta (Poland)—where (from 2018 to 2023) detailed, systematic geodetic, and hydrometric research and an assessment of the ecological conditions were carried out. The presented results show the influence of deflectors on the initiation of fluvial processes in the transverse and longitudinal layouts of the channel. The river channel was narrowed from 6 to 5 m, and the current line shifted by almost 3 m. Changes were observed in the distribution of velocities and shear stresses, varying along the surveyed section of the river. In the first year after their application, an increase in velocity at the deflectors can be observed (from 0.2 m∙s−1 to 0.6 m∙s−1 in the deflector cross-section). In the following years, on the other hand, a clear decrease in velocity was observed in the sections between the deflectors (to 0.3 m∙s−1). The introduction of deflectors resulted in a significant increase in the values of shear stresses (from an average value of 0.0241 N∙m−2 in 2018 to 0.2761 N∙m−2 in 2023) and local roughness coefficients (from 0.045 s∙m−1/3 before the introduction of the deflectors to 0.070 s∙m−1/3 in 2023). Based on analyses of sediment samples, erosion and accumulation of bottom material were initially observed, followed by a subsequent stabilisation of particle size. Differences in grain size were observed, especially in the cross-section of the deflectors (increase in granularity d50% downstream of the deflector from 0.31 mm to 3.9 mm already 2 years after the introduction of deflectors). This study confirmed the positive impact of using deflectors on hydromorphological processes as deflectors facilitate the achievement of a good ecological status, as required by the WFD. The innovation of this paper lies in demonstrating the possibility of using small, simple structures to initiate and intensify fluvial processes, which may contribute to improving the ecological conditions of watercourses. [ABSTRACT FROM AUTHOR]

Multiple barrier system has become a widely adopted method to mitigate debris flows, which consists of smaller barriers that progressively retain the debris to reduce the acceleration and carbon footprint. Different from single barriers, the impact force on multiple barriers depends on the overflow from the upstream barrier. Overflow may substantially accelerate the flow by converting potential energy into kinetic energy with limited energy dissipation. While installing a deflector at the crest of a single barrier suppresses overflow, the efficacy of a deflector in reducing impact force in a multiple barrier system is not well understood yet. In this study, physical tests were conducted using a 28-m-long flume to investigate the impact dynamics of debris flow against dual rigid barriers with a deflector installed at the first barrier. A smoothed particle hydrodynamic (SPH) model was calibrated by back analyzing the flume tests. A numerical parametric study was then conducted to investigate the efficiency of a deflector in reducing impact force from different volumes of debris flow against dual barriers. Newly modified equations are proposed that can reasonably predict the overflow velocity, the velocity after landing, and landing distance considering a deflector. Physical and numerical results reveal that a deflector at the first barrier can efficiently reduce overflow by redirecting the flow to roll back and reduce the landing distance by up to 75%. A deflector at the first barrier can reduce the impact force at the second barrier by up to 90%. [ABSTRACT FROM AUTHOR]

The resistance loss and energy consumption when fluid flows through a tee in an HVAC system are severe. To improve energy efficiency and reduce carbon emissions, a novel tee with a U-shaped deflector is proposed, supported by experiments and numerical simulations. The resistance reduction mechanism of the U-shaped deflector was analyzed according to the viscous dissipation principle and the field synergy principle. The resistance reduction of the novel tee with different deflector angles and a traditional tee were compared. The results show that the resistance loss of the tee was mainly due to the flow separation and deformation of the fluid in the main branch. The relationship between the local resistance coefficient and the diameter ratio of the main-branch pipe was exponential, and the relationship between the local resistance coefficient and the diameter ratio of the main straight pipe was linear. The total resistance loss reduction rate of the tee with the addition of a 26° deflector was the highest, reaching 72.4%, the volume-weighted average synergy angle increased by 1°, and the viscous dissipation decreased by 21.7%. This study provides a reference for the resistance reduction design of complex local components such as tees in HVAC systems. [ABSTRACT FROM AUTHOR]

Deflectors offer a cost-effective solution for enhancing airflow distribution. The purpose of this paper is to investigate the effect of the deflector on the indoor airflow velocity distribution under natural ventilation conditions. The results obtained from numerical simulations are validated through experimental measurements using a reduced-scale model. Subsequently, the validated reduced-scale numerical model was extended to full-size rooms. A full-size numerical simulation method is used to analyze the effect of no deflector, deflectors with different opening width-to-height ratios and deflectors with different opening shapes on the percentage of indoor velocity partitions under natural ventilation conditions. The findings reveal that the judicious installation of deflectors can enhance indoor airflow velocity distribution and increase the percentage of the indoor comfort zone. Deflectors with different opening width-to-height ratios exert distinct influences on indoor airflow velocity distribution. When the deflector opening width-to-height ratio is set at 7/6, the indoor comfort zone percentage reaches its maximum at 75.98%. Furthermore, the shape of the deflector's opening significantly affects indoor airflow velocity distribution, and when the opening shape is a rhombus shape of 4.00 cm x 9.00 cm, the proportion of indoor velocity comfort zone is the largest, which is 75.56%. This study provides a reference for the design and practice of natural ventilation in buildings. [ABSTRACT FROM AUTHOR]

In order to remove the ash built up on the inside wall of the heat exchanger tubes in the combustion chamber of HDT tobacco dryer and promote the heat transfer efficiency, a cleaning device was designed. The device mainly consists of a tube cleaning unit, a deflector cleaning unit, an air compressor and an industrial vacuum cleaner. The flexible grinding head for cleaning the tube and the flexible roller brush for cleaning the deflector are driven by an air motor (rated speed of 4 500 r/min) and an electric motor (rated speed of 1 351 r/min), respectively; and the air motor is driven by compressed air of 0.3 MPa from the air compressor. The removed ash is collected by the industrial vacuum cleaner. The designed cleaning device was tested on the HDT-FX3000 tobacco dryer at Liuzhou Cigarette Factory. The results showed that the average time for cleaning the heat exchanger was reduced from 172 to 63 min, the natural gas consumption for drying a batch of tobacco was reduced from 86.49 m³ to 82.19 m³, and the average power consumption of the combustion chamber was reduced by 15.9%. This device is helpful for promoting the heat transfer efficiency of HDT tobacco dryer and reducing energy consumption in production. [ABSTRACT FROM AUTHOR]

A deflector installed on the side of the cold aisle was proposed to address the issue of poor air distribution uniformity in the vertical direction of the underfloor air supply cold aisle of the closed data center. The orthogonal experimental method was employed to investigate the three factors (height, shape, roughness) and four levels (height:2/2.1/ 2.2/2.3 m; shapes:flat panel, curved panel, equal step height, equal airflow step; surface roughness:smooth, rough, ribbed) of the deflector. Two thermal performance evaluation indicators, the return heat index (IRH) and the return temperature index (IRT) of the supply air, were calculated through numerical simulation for each experimental group. The range analysis method was used to determine the influence weight of each factor, and further numerical simulation analysis was conducted to verify the optimal structural combination of the deflector. The results indicate that the geometric shape of the deflector is the main factor affecting the thermal performance of the data center, followed by roughness and height size, which have the smallest impact. The IRH of the optimal structural combination is 0.372, and the IRT is 1.69, indicating that it has a good optimization effect on the vertical uniformity of the airflow organization in the data center. When setting up deflectors in practical engineering, priority can be given to curved surfaces.

Deflectors offer a cost-effective solution for enhancing airflow distribution. The purpose of this paper is to investigate the effect of the deflector on the indoor airflow velocity distribution under natural ventilation conditions. The results obtained from numerical simulations are validated through experimental measurements using a reduced-scale model. Subsequently, the validated reduced-scale numerical model was extended to full-size rooms. A full-size numerical simulation method is used to analyze the effect of no deflector, deflectors with different opening width-to-height ratios and deflectors with different opening shapes on the percentage of indoor velocity partitions under natural ventilation conditions. The findings reveal that the judicious installation of deflectors can enhance indoor airflow velocity distribution and increase the percentage of the indoor comfort zone. Deflectors with different opening width-to-height ratios exert distinct influences on indoor airflow velocity distribution. When the deflector opening width-to-height ratio is set at 7/6, the indoor comfort zone percentage reaches its maximum at 75.98%. Furthermore, the shape of the deflector’s opening significantly affects indoor airflow velocity distribution, and when the opening shape is a rhombus shape of 4.00 cm × 9.00 cm, the proportion of indoor velocity comfort zone is the largest, which is 75.56%. This study provides a reference for the design and practice of natural ventilation in buildings.

Ski jumps are commonly used to discharge flow away from release structures into downstream rivers for energy dissipation. However, due to large intersection angles of jet and river flow or the jet impacting position unreasonable, the serious sour of riverbed or bank may occur, threatening the security of hydraulic structure. Hence, the impacting position and direction of jet from ski jump are pressing for research. For obtaining a controllable and desired outflow condition, adding rectangular tetrahedral deflector is a common and effective measure to change the flow direction. In this study, physical experiments and numerical simulation were conducted and the effect of the deflector contraction ratio on the flow deflection angle was revealed. The results indicate that the contraction ratio is a key parameter of the deflector, and a larger contraction ratio contributes to a larger jet deflection angle. Based on the data in the present and previous studies, a new empirical expression for estimating the deflection angle is proposed for rectangular tetrahedral deflector. By contrast with previous research, the calculated result from the expression presents a better agreement with the test data. [ABSTRACT FROM AUTHOR]

The present numerical study employs a passive flow control augmentation mechanism to enhance the hydrodynamic performance of the Savonius hydrokinetic turbine. Two cylindrical deflectors guide the flow over the Savonius rotor blades. The effectiveness of placing the deflectors is examined by positioning them upstream of the returning and advancing blades. The Savonius hydrokinetic rotor’s efficiency is improved by incorporating Deflector1 to decrease the counteracting torque from the returning blade and Deflector2 to magnify the positive torque produced by the advancing blade. The study focuses on finding a suitable position (L1) and size (d1) of Deflector1 while keeping the size (d2) and position (L2 and α) of Deflector2 fixed. The diameter of Deflector1 (d1) changes as d1=d =0 .15, 0.20, 0.25, 0.30, and 0.35 for each position, L1=d of 1.35, 1.65, 1.95, and 2.25. The study reports that the augmented Savonius turbine operates most efficiently at d1=d =0 .15, L1=d = 1.65, corresponding to a tip speed ratio of 0.9. The deflector-assisted Savonius hydrokinetic turbine enhances the power coefficient (CP) by 54.1% in comparison to the ordinary Savonius rotor lacking deflectors. Further, utilizing cylindrical deflectors upstream of the Savonius hydrokinetic rotor improves the operating TSR range of the Savonius hydrokinetic turbine. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Railway Science & Engineering is the property of Journal of Railway Science & Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to solve the problem of low air speed at the spark plug side of conventional air-cooled engine, a cooling air duct was designed inside the cylinder head of an air-cooled engine of a tricycle. The structure of the cooling air duct of the air-cooled engine was numerically simulated and analyzed using CFD( computational fluid dynamics) method. The results showed that the cooling air speed in the cooling air duct of the cylinder head under the original cooling air duct was low, and the cooling air speed near the spark plug and around the intake duct was also low, which was not conducive to the overall cooling of the cylinder head. By adjusting the lay- out of the guide vanes in the cooling air duct of the cylinder head and increasing the air inlet area at the exhaust side, the cooling air volume at the spark plug side and exhaust side of the cylinder head is significantly increased, which is conducive to the cooling of the high-temperature area of the cylinder head. According to the experimental verification, the temperature of spark plug gasket of cylinder head can be reduced by 23 ℃ under the improvement design of the cylinder head. The research results can provide simulation data support and theoretical guidance for the design of cylinder head cooling air duct. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Nanchang University (Engineering & Technology) is the property of Nanchang University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To enhance the effectiveness of pollution collection and self-purification within a circulating water aquaculture system, a regular octagonal aquaculture tank structure with a deflector was developed. A three-dimensional non-constant flow field numerical calculation model was established. Based on the validation of the calculation method, this study investigated the impact of geometric parameters and the positioning of flow-guide discs on hydrodynamic traits, including flow velocity distribution, vortex strength, wall shear stress, and water body mixing uniformity. The findings indicate that, while keeping the ratio of deflector diameter to pond width constant, elevating the deflector height yields a pattern of diminishing and then augmenting vortex columns at the center of the flow field. Additionally, the number of vortex rings displays a similar tendency, transitioning from decrease to increase and gradually evolving into an annular configuration from its irregular shape. Similarly, at the same height, raising the ratio of deflector diameter to pond width leads to an initial growth and subsequent reduction in the vortex column, while the count of vortex rings experiences a growth followed by a relatively stable phase. This initial growth in vortex rings is followed by a largely consistent state. By situating the deflector 20--40 mm above the pool bottom and maintaining a pool width-to-diameter ratio of 0.05--0.08, an amplified velocity gradient close to the pool's base can be achieved. Furthermore, this installation reduces collisions between the pool wall surface and the water body, enhancing vortex strength and promoting hydraulic mixing uniformity. This configuration fosters the necessary hydrodynamic conditions for the aggregation and expulsion of particulate matter. [ABSTRACT FROM AUTHOR]

This paper aims to enhance the performance of H-Darrieus Vertical Axis Wind Turbine (VAWT) via introducing upstream deflectors. The impact of this addition has been investigated and discussed through different deflector configurations. The turbine performance before and after adding different wind rotor barriers was compared. A two dimensional, incompressible, transient, and turbulent flow model was built up in order to simulate the air flow around the turbine blades. Model verification and validation were performed through comparing the model solutions using different mesh sizes, time steps, turbulent models, and discretization schemes. Computational Fluid Dynamics (CFD) models were validated to provide novel insights on the effect of the deflectors on the aerodynamic characteristics of a VAWT blades. Results showed that the presence of a single deflector increases the highest value of the moment coefficient of the bare configuration by 24%, either increases the negative torque values, while two defectors increase the maximum value by 22% and the overall average value of the moment coefficient over the optimal range for the tip speed ratio.

Copyright of Petroleum Refinery Engineering is the property of Petroleum Refinery Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The resistance loss and energy consumption when fluid flows through a tee in an HVAC system are severe. To improve energy efficiency and reduce carbon emissions, a novel tee with a U-shaped deflector is proposed, supported by experiments and numerical simulations. The resistance reduction mechanism of the U-shaped deflector was analyzed according to the viscous dissipation principle and the field synergy principle. The resistance reduction of the novel tee with different deflector angles and a traditional tee were compared. The results show that the resistance loss of the tee was mainly due to the flow separation and deformation of the fluid in the main branch. The relationship between the local resistance coefficient and the diameter ratio of the main-branch pipe was exponential, and the relationship between the local resistance coefficient and the diameter ratio of the main straight pipe was linear. The total resistance loss reduction rate of the tee with the addition of a 26° deflector was the highest, reaching 72.4%, the volume-weighted average synergy angle increased by 1°, and the viscous dissipation decreased by 21.7%. This study provides a reference for the resistance reduction design of complex local components such as tees in HVAC systems.

Some recent studies show that the aerodynamic efficiency of the Savonius wind turbine can be improved by adding a properly designed deflector upstream of the rotor blade. However, these deflector designs can only improve the turbine efficiency in specific flow directions, which causes the loss of omnidirectionality. In this paper, a passive deflector is designed to solve this problem. The passive deflector can passively adjust its position with the change in wind direction so that the efficiency of the Savonius rotor is improved regardless of wind directions. For the sake of investigating the aerodynamic performance of the Savonius rotor with the new deflector, three-dimensional computational fluid dynamics simulations are performed at different operating conditions. The CFD method uses a set of high-quality structured grids and is validated with existing empirical data. The results show that the passive deflector can obtain a stable orientation adaptively according to the wind direction, and the maximum efficiency of the classical Savonius rotor is increased by 24.91% using the passive deflector.

Introduction: Despite the fact that, in recent years, the construction of long-span bridges has been extensively developed, cases of bridge structures buckling in wind still occur, but the issue of their interaction with wind has not been sufficiently studied. Purpose of the study: We aimed to improve the structural integrity and operational safety of long-span bridge structures by conducting a computational and experimental study on the effect of various designs of aerodynamic dampers on the aerodynamic stability of such structures. Methods: The study was performed in two stages. At the first stage, preliminary two-dimensional numerical modeling was conducted to study the effect of various designs of aerodynamic dampers on the wind flow over selected bridge spans. Based on the results of the preliminary two-dimensional numerical modeling, we chose the most effective designs of aerodynamic dampers and made their models to conduct experimental studies on aerodynamic stability on a special test bench. Results: Based on the obtained computational and experimental results, we analyzed the effectiveness of various designs of aerodynamic deflectors and fairings used to improve the aerodynamic stability of the standard bridge structure under consideration. Discussion: For a span with one main girder, we determined the deflector design that reduces the vibration amplitude at high wind velocities.

ABSTRACT Aerator systems promote additional insertion of air into the flow and can reduce the risk of cavitation and consequent damage to hydraulic structures. This work analyzes the hydrodynamic pressures on the steps of a physical model (with a chute inclination of 53.13º) subjected to different aeration conditions. When comparing the results with different air intake coefficients in the flow, it was concluded that the incorporation of air does not change in a generalized way all the statistical parameters associated with hydrodynamic pressures on the steps. However, with the insertion of air in the flow, there was an increase in the minimum pressure values measured in the region of the jet impact and downstream. Empirical equations for predicting the distribution of pressures on the steps under induced aeration conditions were proposed, valid for structures whose ratio between the height of the deflector and the height of the steps is equal to 0.167, with an aerator system installed at the beginning of the stepped chute.

Self-scouring water-intake basins are modem hydraulic structures, which are the water-inlet part of surface water intakes, that are difficult to design and require physical modeling. The parameters and main design features of a water-intake basin can only be assessed in a hydraulic laboratory. Data for calculations are provided based on an analysis of actual data. The main parameters of a water-intake basin are its dimensions depending on the capacity of the water intake. [ABSTRACT FROM AUTHOR]

Copyright of Railway Construction Technology is the property of Railway Construction Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The unsteady RANS equations for a two-dimensional hydrofoil were solved using ANSYS Fluent to model and simulate the hydrofoil at a constant Reynolds number, Re, of 2 × 105 and a fixed reduced frequency, f*, of 0.14. The simulations were performed by varying parameters, such as the number of deflectors N, tilt angle of the deflectors β, and vertical spacing of the deflectors J* = J/c, to determine the effect of the upstream deflector's position on the hydrofoil's performance. The results demonstrated that the deflector was effective at redirecting the separated flow away from the edges, which was then amplified downstream before colliding with the leading edge of the oscillating hydrofoil to increase power extraction. The performance of the oscillating hydrofoil was highly reliant on all three studied parameters. The hydrofoil with two deflectors (N = 2) displayed marginally superior power extraction capability compared to the hydrofoil with a single deflector (N = 1). Furthermore, the hydrofoil with the rightward inclined deflector at a low tilt angle (−5° ≥ β ≥ −10°) exhibited relatively better power extraction performance than the others. The best deflector design increased the hydrofoil's cycle-averaged power coefficient by approximately 32% compared to a hydrofoil without a deflector. The vortex structures revealed that the flow evolution and power extraction performance were dependent on the size, robustness, and growth rate of the leading edge vortex (LEV) as well as the timing of LEV separation. The power extraction efficiency of an oscillating hydrofoil increased in the mid downstroke and upstroke due to the formation of a more robust LEV when the hydrofoil–deflector interaction was advantageous, but it dropped in the wing reversal due to the early separation of the LEV when the hydrofoil–deflector interaction was counterproductive. [ABSTRACT FROM AUTHOR]

Highly modified riverbeds are not able to spontaneously reproduce natural processes. The restoration of natural river systems is an important challenge to modern river engineering. Various procedures and solutions, both technical and non-technical, are applied in this process. This involves looking for simple solutions that are close to nature and that interfere with river ecosystems to a minimal extent. One of these solutions is deflectors, which constitute a type of simplified spur. This study presents the results of the research on the transformations of hydromorphology and macrophytes on selected sections of the Flinta River, which represents the most common type of river in the Central European Lowlands (a small river with a sandy substrate). Two neighbouring sections of the watercourse were selected. The first one has not been subject to any regulatory measures for over 30 years and is undergoing spontaneous restoration, while the second one was significantly altered (straightened, cleared of hydrophytes, and desilted) ten years ago. Three deflectors were introduced in this section in the years 2017–2018. Research conducted on both sections enabled the determination of the possibility of initiating renaturalisation processes by way of implementing simple solutions in the form of low-cost wooden deflectors. It also provided the basis for the assessment of the impact the measures taken had on the hydromorphological status of the watercourse and on macrophytes. Based on the studies conducted, it was possible to determine the size, dynamic, and scope of the changes taking place in the river under various conditions of its transformation, including those resulting from anthropopressure. [ABSTRACT FROM AUTHOR]

In order to study the influence of external wind speed on deck and deflection angle of deflector on the wake field of the aircraft engine on aircraft carrier, taken the tail nozzle of aircraft engine and deflector of aircraft carrier in foreign countries as the research objects, the numerical simulation is conducted for the wake field of the aircraft engine by the computational fluid dynamics and 3D Reynolds averaged Navier-Stokes equation and the k-ε turbulence model. The results show that the high-temperature and high-speed airflow in the wake field is mainly distributed in the area between the deflector and the nozzle. As the deflection angle of deflector decreases from 50° to 40°, the effect of upward deflection in the wake flow decreases, and the spanwise distribution range of streamline decreases. Also, the unsafe area on both sides of the deflector decreases from 31.9 m to 20.2 m, while the unsafe area behind the deflector increases from 13.5 m to 19.4 m. As the wind speed on deck increases from 0 m/s to 15 m/s, the unsafe area behind the deflector increases from 17.5 m to 53.1 m, while the unsafe area on both sides of the deflector decreases from 32.4 m to 17.8 m. The numerical simulation results can be used to guide the safety operation of the staff on the aircraft carrier flight deck and to optimize the surface equipment layout of the aircraft carrier.

In this research, the models of Inflatable weirs with internal pressures of 0.5 and 1.4 at three heights of 0.15, 0.2 and 0.25 m were constructed. The deflectors were used in two geometric sections, including rectangular and triangular shapes, and they were installed at angles of 30, 45, and 60 degrees downstream of the weir body. The results showed that the value of the Cd changes between 0.28 and 0.35 while the range of the ratio of the upstream flow head on the crest to the radius of the downstream side of the inflatable weir varies between 0.2 and 1.5. The flow by crossing over the inflatable weir and colliding with the surface of the downstream stilling basin loses its energy by about 10–85%. The relative horizontal distance of the projectile-jet from the crest varies between 1.6 and 2.8. The effect of the deflector on the Cd is negligible due to being located in the supercritical part of the weir. Examination of the obtained results declared that the deflector has a considerable effect on energy dissipation. HIGHLIGHTS The hydraulic properties of the Inflatable weir, including discharge coefficient (Cd), the flow energy dissipation ratio (EDR), and the profile of the outlet jet of the deflector were investigated.; The stage-discharge relation (rating curve) of inflatable weirs was provided.; The effects of defector and its installation angle on the properties of outlet jet and energy dissipation have been investigated.;

Several factors, including the accessibility of energy sources, influence the movement of human activities in this era. However, humans still rely on fossil energy sources. For example, petroleum is non-renewable and can pollute the environment. As a result, researchers have recently been competing to produce various forms of using renewable energy sources. Ocean current energy is one of Indonesia's greatest energy potentials and a hydrokinetic turbine is a device that can harness it. Due to its ability to run on low-speed currents, the vertical-type Savonius turbine has been developed by numerous researchers up until this point. However, there has not yet to be much advancement in the cross-flow type Savonius turbine. The turbine's performance is investigated in this study by adding a flow deflector because the water flow that propels the returning blade is diverted and intensifies the advancing blade flow. Computational Fluid Dynamics (CFD) software has been used to conduct the analysis. The deflector has been added, and the results have showed an average performance improvement of 12% in overall variations. The maximum Cp of 0.299 has been achieved with a deflector configuration angle of 42° at a TSR of 0.74. [ABSTRACT FROM AUTHOR]

Due to the large height and span of indoor spaces, efficient indoor ventilation performance may be difficult to achieve using the side air supply for large halls, to control the indoor air pollutants or reduce the infection risk, such as the transmission of COVID-19 within the breathing zone of occupants. An efficient Ventilation Mode with Deflector and Slot air outlets (VMDS) was developed by this study. The use of a deflector with slot air outlets was introduced by utilizing jet collision and adhesion effect to accentuate the ventilation performance of the side air supply for the large space. The numerical simulation model used in this study was validated experimentally. The VMDS was compared with three other side air supply modes used in large spaces, and the results were evaluated comprehensively. The results show that VMDS is effective in reducing indoor air pollutant concentrations and transmission of infectious diseases in large spaces while satisfying the energy efficiency and thermal comfort requirements. Compared with the common side-supply and side-return ventilation modes, VMDS can reduce indoor air pollutant concentration by nearly 40%, reduce the transmission risk of infectious disease to less than 1% at a low air change rate and increase the ventilation efficiency from about 0.85 to about 1.2. In addition, VMDS can theoretically reduce ventilation energy consumption by about 85%. [ABSTRACT FROM AUTHOR]

This paper aims to enhance the performance of H-Darrieus Vertical Axis Wind Turbine (VAWT) via introducing upstream deflectors. The impact of this addition has been investigated and discussed through different deflector configurations. The turbine performance before and after adding different wind rotor barriers was compared. A two dimensional, incompressible, transient, and turbulent flow model was built up in order to simulate the air flow around the turbine blades. Model verification and validation were performed through comparing the model solutions using different mesh sizes, time steps, turbulent models, and discretization schemes. Computational Fluid Dynamics (CFD) models were validated to provide novel insights on the effect of the deflectors on the aerodynamic characteristics of a VAWT blades. Results showed that the presence of a single deflector increases the highest value of the moment coefficient of the bare configuration by 24%, either increases the negative torque values, while two defectors increase the maximum value by 22% and the overall average value of the moment coefficient over the optimal range for the tip speed ratio. [ABSTRACT FROM AUTHOR]