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Screws are a versatile method of fixation and are often used in orthopaedic surgery. Various specialised geometries are often used for bone screws to optimise their fixation strengths in limited spaces at the expense of manufacturing costs. Additionally, ongoing research is looking to develop systems/models to automatically optimise bone screw tightening torques. For both applications, it is desirable to have a test rig for inserting screws in a regulated, instrumented, and repeatable manner. This work presents such a test rig primarily used for the validation of optimal torque models; however, other applications like the above are easily foreseeable. Key features include controllable insertion velocity profiles, and a high rate measurement of screw torque, angular displacement, and linear displacement. The test rig is constructed from mostly inexpensive components, with the primary costs being the rotational torque sensor (approx. 2000 €), and the remainder being approximately 1000 €. This is in comparison to a biaxial universal testing machine which may exceed 100,000 €. Additionally, the firmware and interface software are designed to be easily extendable. The angular velocity profiling and linear measurement repeatability of the test rig is tested and the torque readings are compared to an off-the-shelf static torque sensor. [ABSTRACT FROM AUTHOR]

The efficiency of bevel and hypoid gears is, alongside load capacity, one of their most important design criteria. To consider the efficiency of bevel and hypoid gears during the development and design process, validated calculation methods based on experimental investigations are necessary. However, the isolated experimental investigation of the load-dependent power losses of bevel and hypoid gears has not been adequately investigated, as most of the experimental investigations consider the complete gearbox. This paper presents a test rig that allows for the experimental investigation of the efficiency of bevel and hypoid gears with a measurement uncertainty of the efficiency of ∆ η ≤ ± 0.08 % according to the Guide to the Expression of Uncertainty in Measurement (GUM). Using the developed test rig, experimental investigations on the efficiency behavior of bevel and hypoid gears regarding the influence of the axial offset, driving direction, and microgeometry are carried out for different operating points varying in circumferential speed and load. This paper discusses the methodology and the first experimental results of a study on the efficiency of bevel and hypoid gears in detail. [ABSTRACT FROM AUTHOR]

The automotive industry is currently transforming, primarily due to the rise of electric and hybrid vehicle technologies and the need to reduce vehicle mass and energy losses to decrease consumption, pollution, and raw material usage. Additionally, road surface manufacturers emphasize improving pavement durability and reducing rolling noise. This necessitates precise load condition definitions and drives the need for reliable wheel testing benches. Many current benches use abrasive-coated rollers or synthetic tapes, but devices capable of testing on actual road surfaces are rare. In this work, a novel device for testing tire-pavement interaction is proposed. The system features a cart moving along a closed-track platform, ensuring test repeatability and enabling structural durability tests on uneven surfaces with installed obstacles. The cart is equipped with a cantilever arm capable of supporting either a testing wheel with customizable dimensions and kinematic parameters or a tire integrated with a complete suspension system, moving along a customizable pavement surface. The system includes actuators and sensors for applying vertical loads and adjusting the alignment of the testing wheel (slip angle, camber angle, etc.), allowing the characterization of tire behavior such as wear, fatigue, rolling noise, and rolling resistance. Multibody simulations were performed to evaluate the bench's feasibility in terms of kinematics, power requirements, and structural loads. Results confirmed how this novel test bench represents a promising advancement in tire testing capabilities, enabling comprehensive studies on tire performance, noise reduction, and the structural dynamics of vehicle subsystems. [ABSTRACT FROM AUTHOR]

Increasing efficiency while reducing emissions leads to high mean effective pressures, high compression ratios and increasingly lean operation for spark ignited large gas engines. Despite these boundary conditions, gas engines must be operated between knocking and misfiring at low cycle-to-cycle fluctuations. The excess air ratio and the ignition process of the lean mixture greatly influence the stability of the combustion process. To enable sufficiently low cycle-to-cycle fluctuation of the combustion process despite the ever increasing excess air ratio levels, it is necessary to understand and investigate the sub-areas of the engine process, for example, ignition, flow condition and mixture formation. This paper focuses on one sub-area of conventional spark ignition, the influence of the electric arc root position on the origin and stretching of the electric arc, because electric arc behavior is considered important in the subsequent combustion process. The results show that electric arc roots on the downstream end of the electrodes tend to enable a longer electric arc length at the first electric arc short circuit (i.e. the first abrupt shortening of the electric arc during its spark duration) than electric arcs with electric arc roots on the upstream ends of the electrodes. [ABSTRACT FROM AUTHOR]

Biomass combustors provide space heating by converting chemical energy in woody biomass into low-temperature thermal energy. Thermoelectric generators (TEGs) can generate electricity from the heat flux without significantly reducing heating performance. However, most current TEGs are small (40 mm × 40 mm), requiring many TEG elements to generate useful power from a biomass combustion-based space heater. This work compares the electrical generation potential of an array of small TEGs with a larger (80 mm × 120 mm) TEG in a vertical configuration representative of a residential heating appliance. An experimental facility was developed for various representative cold-side ducts and controllable hot-side temperature and cooling airflows, and the Taguchi method was used to evaluate the impacts of temperature, airspeed, and ducting configurations. The results indicate that temperature and airspeed significantly influence TEG power, while ducting configurations have an insignificant influence. The large TEG achieved more consistent temperatures but produced lower power than an array of smaller TEGs with the same total area. The study emphasizes optimizing TEG design and operating conditions to enhance electricity generation efficiency in space heating combustors. [ABSTRACT FROM AUTHOR]

The evolution of aircraft wing development has seen significant progress since the early days of aviation, with static testing emerging as a crucial aspect for ensuring safety and reliability. This study focused specifically on the engineering phase of static testing for the Clean Sky 2 T-WING project, which is dedicated to testing the innovative composite wing of the Next-Generation Civil Tiltrotor Technology Demonstrator. During the design phase, critical load cases were identified through shear force/bending moment (SFBM) and failure mode analyses. To qualify the wing, an engineering team designed a dedicated test rig equipped with hydraulic jacks to mirror the SFBM diagrams. Adhering to specifications and geometric constraints due to several factors, the jacks aimed to minimize the errors (within 5%) in replicating the diagrams. An effective algorithm, spanning five phases, was employed to pinpoint the optimal configuration. This involved analyzing significant components, conducting least square linear optimizations, selecting solutions that met the directional constraints, analyzing the Pareto front solutions, and evaluating the external jack forces. The outcome was a test rig setup with a viable set of hydraulic jack forces, achieving precise SFBM replication on the wing with minimal jacks and overall applied forces. [ABSTRACT FROM AUTHOR]

This work presents a test rig developed for testing the lifetime of electrically and cyclically activated shape memory alloy wires. This test rig is developed to provide information on the functional and structural fatigue of the wires. Therefore, electrical activation on the test rig can be carried out using different activation profiles, because it is of great research interest to determine whether those profiles have a significant influence on the wire's lifetime and functional behavior. The test rig monitors the process parameters such as stroke, current, voltage, and force. After presenting the electrical and mechanical design of the test rig, this publication evaluates an initial series of tests to demonstrate its functionality. Three different activation profiles are run in parallel on four identical test rig setups and are then evaluated. The functionality of the test rig is verified by a detailed evaluation of the process data on the one hand, and by comparing the results with existing literature on the other. The functionality of the test rig can thus be verified. At the same time, the strong influence of the different activation profiles on both the lifetime and the functional properties of the shape memory alloy wires becomes clear. [ABSTRACT FROM AUTHOR]

In order to explore the formation mechanism of corrugation in railway systems, the corrugation phenomenon is analyzed in detail from points of view of micro contact and material wear using the self-designed scale twin discs test rig. The results show that the longitudinal creep force is not a sufficient condition for corrugation formation, and the transverse creep force is indeed an important condition. Considering the scale factor (1:4) of the test model, it can be obtained that the passing frequency of corrugation on the rail wheel surface of 1700.78 Hz corresponds to the passing frequency of corrugation in the actual system of 425.20 Hz. Due to the frequency-fixed characteristic of corrugation, the above frequency is consistent with the line measurement results in the relevant literatures. The stick-slip analysis shows that the transverse slip of 0.0084∼0.3437 mm is greater than the longitudinal one of 0.0003∼0.1205 mm in the contact area. Combining experimental tests with the numerical analysis, it can be concluded that the theoretical mechanism of corrugation formation is that under the condition of transverse creep force saturation, the unstable vibration at a specific frequency causes the wear to have the frequency-fixed characteristic and eventually form corrugation, and the transverse wear has a greater influence on the evolution of corrugation. [ABSTRACT FROM AUTHOR]

Capturing internal flow experimentally presents significant challenges due to the asymmetric propagation and strong unsteadiness of a stall cell in the circumferential direction. In this study, a low-speed counter-rotating axial compressor test rig was designed based on a counter-rotating compressor to immobilize a stall cell and measure its internal flow characteristics. Determining an appropriate speed ratio that is capable of stabilizing the circumferential position of the stall cell in the counter-rotating compressor enabled visualization measurements to be conducted successfully. The preliminary results demonstrated the successful immobilization of the stall cell using an appropriate rotating speed ratio. Furthermore, the oil flow visualization measurements confirmed the presence of a distinct stall cell structure on the casing wall. This work represents an innovative approach towards immobilizing stall cells in axial compression systems. [ABSTRACT FROM AUTHOR]

Background: The performance and endurance of lubricating greases is often assessed through model tests (like four-ball tests or SRV tests). This approach has some limitations, especially when greases with special fillers are investigated, because simplified laboratory test conditions can never replicate real operating conditions. Objective: For a more reliable assessment on the performance of a lubricating grease, lubricants must be tested in close-to-actual operational conditions, e.g. through component tests. This paper presents both the design and implementation of a dedicated test rig to test lubricating greases through middle-sized thrust ball bearings. Methods: The test rig design is optimized to monitor the effectiveness of lubrication and determine the useful life of grease by recording representative parameters, namely bearing temperature at different location in the bearing, vibration level, and electric contact resistance (ECR) through the bearing. Results: The results of a couple of assessment tests are presented and confirm that the test rig is working as expected. Conclusions: The chart of the parameters being monitored shows that the instant performance of grease lubrication can be tracked during the endurance tests, and grease failure identified. The special mechanical layout of the rig also allows the user to obtain additional information that is usually not available in other commercial greased bearing testers. This work is meant to be the first step of the development a new approach to evaluate the grease lubrication performance and a few experimental results are included as they are intended as a functional validation of the prototyped test rig.

The efficiency of bevel and hypoid gears is, alongside load capacity, one of their most important design criteria. To consider the efficiency of bevel and hypoid gears during the development and design process, validated calculation methods based on experimental investigations are necessary. However, the isolated experimental investigation of the load-dependent power losses of bevel and hypoid gears has not been adequately investigated, as most of the experimental investigations consider the complete gearbox. This paper presents a test rig that allows for the experimental investigation of the efficiency of bevel and hypoid gears with a measurement uncertainty of the efficiency of ∆η≤±0.08% according to the Guide to the Expression of Uncertainty in Measurement (GUM). Using the developed test rig, experimental investigations on the efficiency behavior of bevel and hypoid gears regarding the influence of the axial offset, driving direction, and microgeometry are carried out for different operating points varying in circumferential speed and load. This paper discusses the methodology and the first experimental results of a study on the efficiency of bevel and hypoid gears in detail.

As the piston ring is inserted into the bore, it is forced against the liner by radial tension, thereby creating a seal. Radial tension not only affects the piston ring's seal, but also significantly influences its tribological properties. To investigate the effect of non-uniform radial tension of piston ring on the lubrication properties, a contact finite element model of piston ring and cylinder liner tribo-pairs is constructed in this study. The contact pressure distribution between the tribo-pairs is determined based on this model. The obtained pressure is then regarded as the non-uniform radial tension of the ring, which is fitted to a formula. The formula is validated in two ways. Firstly, its generality is verified by simulating several different piston rings using the contact model and comparing their results with the formula. Second, a test rig was designed and set up to measure the piston ring's circumferential tension. To verify the formula's accuracy, an equivalent principle model of distributed pressure and concentrated force was proposed. This formula is used as an initial force to modify the piston ring mixed lubrication model. Based on this model, the lubrication performance of the piston ring with uniform radial tension and non-uniform radial tension into consideration is investigated. The findings demonstrate that the piston ring radial tension is of significance to its lubrication performance and can be modified to lessen local friction and wear issues, particularly those related to the piston ring gap, and thus improve the dependability of the piston ring. [ABSTRACT FROM AUTHOR]

The assessment of fish passage conditions in hydroelectric turbines consists of identifying and quantifying physical magnitudes leading to increased risks of injury of fish passing through turbines in operation. Such assessments are usually carried out either with the use of computer-based methods during design or with field testing of live fish and sensors passing through prototypes. A method in between consists of test rig experimentation, which is critical for testing fish-focused design concepts and offers the opportunity for implementing the most effective design measures for improved fish survivability. However, fish-related assessments in test rigs are not sufficiently documented for industrial applications. This work presents the main findings of an experimental campaign to quantify fish-related hydraulic magnitudes in a physical model of a Kaplan turbine in a commercial test rig. Two operating conditions were tested by releasing miniaturized autonomous sensor devices (termed Sensor Fish Mini) at the turbine intake flow, passing them through the runner in motion and recovering them at the draft tube exit. During passage, time series of acceleration, absolute pressure and rotational velocity were recorded. The recordings were then interpreted to determine the magnitude and likely location of hydraulic stressors hazardous to fish. The statistical tests on the reported measurements indicated that low pressure, collisions on the runner and rotations in the draft tube were not different between the two tested operating points. On the other hand, pressure drop and collision rates on the distributor differed considerably as a function of net head. The outcomes of this investigation showed that test rig evaluations of fish-related properties with Sensor Fish Mini can contribute to an evidence-based development of turbine geometries designed for providing safer passage conditions. Future work will investigate the scaling of test rig measurements to hydraulically equivalent magnitudes in the prototype and their biological consequences.

In planetary science, visible (Vis) and near-infrared (NIR) reflectance spectra allow deciphering the chemical/mineralogical composition of celestial bodies’ surfaces by comparison between remotely acquired data and laboratory references. This paper presents the design of an automated test rig named Exoland Simulator equipped with two reflectance spectrometers covering the 0.38–2.2 µm range. It is designed to collect data of natural/synthetic rocks and minerals prepared in the laboratory that simulate the composition of planetary surfaces. The structure of the test rig is conceived as a Cartesian robot to automatize the acquisition. The test rig is also tested by simulating some project trajectories, and results are presented in terms of its ability to reproduce the programmed trajectories. Furthermore, preliminary spectral data are shown to demonstrate how the soil analogs’ spectra could allow an accurate remote identification of materials, enabling the creation of libraries to study the effect of multiple chemical–physical component variations on individual spectral bands. Despite the primary scope of Exoland, it can be advantageously used also for tribological purposes, to correlate the wear behavior of soils and materials with their composition by also analyzing the wear scars.

The automotive industry is currently transforming, primarily due to the rise of electric and hybrid vehicle technologies and the need to reduce vehicle mass and energy losses to decrease consumption, pollution, and raw material usage. Additionally, road surface manufacturers emphasize improving pavement durability and reducing rolling noise. This necessitates precise load condition definitions and drives the need for reliable wheel testing benches. Many current benches use abrasive-coated rollers or synthetic tapes, but devices capable of testing on actual road surfaces are rare. In this work, a novel device for testing tire-pavement interaction is proposed. The system features a cart moving along a closed-track platform, ensuring test repeatability and enabling structural durability tests on uneven surfaces with installed obstacles. The cart is equipped with a cantilever arm capable of supporting either a testing wheel with customizable dimensions and kinematic parameters or a tire integrated with a complete suspension system, moving along a customizable pavement surface. The system includes actuators and sensors for applying vertical loads and adjusting the alignment of the testing wheel (slip angle, camber angle, etc.), allowing the characterization of tire behavior such as wear, fatigue, rolling noise, and rolling resistance. Multibody simulations were performed to evaluate the bench’s feasibility in terms of kinematics, power requirements, and structural loads. Results confirmed how this novel test bench represents a promising advancement in tire testing capabilities, enabling comprehensive studies on tire performance, noise reduction, and the structural dynamics of vehicle subsystems.

One test rig comprising two blades and dual under-platform dampers (UPDs) was built to enhance the understanding of the dynamic response behavior of blades with dual UPDs. A turnbuckle was applied to enable the smooth and uninterrupted linear adjustment of the normal load on the dual UPDs. Non-contact vibration-response measurements were achieved through eddy-current displacement sensors. Contact excitation was employed using an electromagnetic exciter to determine the magnitude of the excitation load, which was measured using a force sensor mounted on the excitation rod. A feedback system was established to maintain a constant magnitude of the excitation force throughout the excitation process. The chosen experimental variables include the normal load, the amplitude of the excitation force, the effective contact area, and the position of the damper action. The frequency response function of the blade under various experimental parameters was obtained through frequency sweeping under sinusoidal excitation. The influence of each parameter on the dynamic characteristics of blades was studied. The results demonstrate that the double-layer damping system offers distinct advantages over its single-layer counterpart. The upper damping has a wider frequency-adjustment range and a lower resonance amplitude and takes a larger share of the damping efficiency. [ABSTRACT FROM AUTHOR]

• Design and construction of single wheel test rig for Ocean World rover is presented. • Built using commercially available mechanical parts, motors, actuators, and sensors. • Test rig allows control of slip ratio, vertical load, slip angle, and camber angle. • Modular test-bed can simulate fine-grained ice, sharp ice, and ice boulder fields. Ocean Worlds such as Europa and Enceladus are known to harbor subsurface liquid water oceans under their icy crust and are high-priority targets for in situ exploration. Compared to the Moon and Mars, Ocean Worlds likely present a significantly more challenging environment for surface mobility systems due to the extremely cold temperature, high radiation dosage, and poorly constrained material properties under these conditions. Small-diameter wheels such as those used by Mars rovers are prone to slip-sinkage in loose soil and damage from sharp rock and ice formations. A 4-wheel rover with a simple drive system and large deployable compliant tires is proposed as a solution for extreme terrain mobility on Ocean World surfaces. The present work describes the design and construction of a single wheel test rig and a prototype large-diameter deployable wheel for Ocean World rovers and initial test results. The test rig allows independent control of the vertical load, slip ratio, slip angle, and camber angle, and accommodates large-diameter deployable wheels. The test rig features a modular test bed that can simulate varied surface features such as fine-grained ice, smooth hard ice, sharp ice formations, and large ice boulder fields. [ABSTRACT FROM AUTHOR]

To study the braking performance of linear eddy current brake (LECB) for high-speed maglev trains, experimental studies are usually carried out using a track wheel with a finite radius and a track wheel eddy current brake (TWECB) with a certain radius of curvature. However, the geometrical differences between the two braking methods due to the track radius will lead to differences in their effective excitation air gap during operation. Therefore, the excitation air gap model and eddy current braking force model of TWECB and LECB are developed in this study. Through the excitation air gap model and eddy current braking force model proposed in this paper, the difference in braking performance between TWECB and LECB in the velocity domain and operating air gap domain can be obtained for different track radii. The correctness of the finite element analysis (FEA) method is verified by experimental data, and the eddy current density, braking force and air gap flux density formed by eddy current braking at different track radii are analysed using the finite element method. The results show that an appropriate test track radius can significantly improve the accuracy of TWECB in estimating the braking performance of LECB. [ABSTRACT FROM AUTHOR]

During the maintenance period of a future fusion reactor power plant, called DEMOnstration Power Plant (DEMO), remotely handled casks are required to confine and handle DEMO in-vessel components during their transportation between the reactor and the active maintenance facility. In order to limit the dispersion of activated dust, a Contamination Control Door (CCD) is designed to be placed at an interface between separable containments (e.g., vacuum vessels and casks) to inhibit the release of contamination at the interface between them. The remotely operated CCD—technically, a double lidded door system—consists of two separable doors (the cask door and port door) and three different locking mechanisms: (i) between the cask door and cask, (ii) between the cask door and port door and (iii) between the port door and port. The locking mechanisms are selected and assessed according to different criteria, and the structure of the CCD is optimized using an Abaqus Topology Optimization Module. Due to the elastic properties of the CCD, deflections will occur during the lifting procedure, which may lead to malfunctions of the CCD. A test rig is developed to investigate the performance of high-risk components in the CCD in the case of deflections and also malpositioning. Misalignment can be induced along three axes and three angles intentionally to test the single components and items. The aim is to identify a possible range of operating in the case of misalignments. It is expected that the proposed CCD design should be able to operate appropriately in the case of ±3 mm translational misalignments and ±1° rotational misalignments.

Biomass combustors provide space heating by converting chemical energy in woody biomass into low-temperature thermal energy. Thermoelectric generators (TEGs) can generate electricity from the heat flux without significantly reducing heating performance. However, most current TEGs are small (40 mm × 40 mm), requiring many TEG elements to generate useful power from a biomass combustion-based space heater. This work compares the electrical generation potential of an array of small TEGs with a larger (80 mm × 120 mm) TEG in a vertical configuration representative of a residential heating appliance. An experimental facility was developed for various representative cold-side ducts and controllable hot-side temperature and cooling airflows, and the Taguchi method was used to evaluate the impacts of temperature, airspeed, and ducting configurations. The results indicate that temperature and airspeed significantly influence TEG power, while ducting configurations have an insignificant influence. The large TEG achieved more consistent temperatures but produced lower power than an array of smaller TEGs with the same total area. The study emphasizes optimizing TEG design and operating conditions to enhance electricity generation efficiency in space heating combustors.

This work presents a test rig developed for testing the lifetime of electrically and cyclically activated shape memory alloy wires. This test rig is developed to provide information on the functional and structural fatigue of the wires. Therefore, electrical activation on the test rig can be carried out using different activation profiles, because it is of great research interest to determine whether those profiles have a significant influence on the wire’s lifetime and functional behavior. The test rig monitors the process parameters such as stroke, current, voltage, and force. After presenting the electrical and mechanical design of the test rig, this publication evaluates an initial series of tests to demonstrate its functionality. Three different activation profiles are run in parallel on four identical test rig setups and are then evaluated. The functionality of the test rig is verified by a detailed evaluation of the process data on the one hand, and by comparing the results with existing literature on the other. The functionality of the test rig can thus be verified. At the same time, the strong influence of the different activation profiles on both the lifetime and the functional properties of the shape memory alloy wires becomes clear.

Vibrations profoundly influence the liquid film formed by spray droplets in spray cooling applications. However, understanding heat transfer mechanisms in the non-boiling region under vibrating conditions is limited in the existing literature. This study aims to bridge this gap by numerically investigating the heat transfer performance of spray cooling in non-boiling regions under vibration using the Lagrange-Euler method. To validate the computational fluid dynamics (CFD) model, experimental measurements of spray heat transfer were conducted on a heated vibrating surface test rig. The results demonstrate that the average film thickness (AFT) and average film velocity (AFV) increase at lower frequencies, leading to a decrease in the heat transfer coefficient. Conversely, the AFT decreases at higher frequencies while the AFV remains relatively constant. This reduction in AFT enhances the heat transfer coefficient, resulting in an up to 12% improvement in heat transfer performance. When a larger vibration amplitude is introduced, a higher inertial force acts on the liquid film, causing it to converge towards the centre. Generally, the heat transfer coefficient of spray cooling in the non-boiling region decreases as the vibration amplitude increases.

This article presents an experimental study on load-independent power losses in oil-jet lubricated deep-groove ball bearings. These experiments were performed under different operating conditions. Rotational speed, lubricant temperature, oil flow rate, and rolling element bearings dimensions were varied to quantify their influence on power losses. A load-independent power losses model for rolling element bearings has been proposed in a companion article and was used here to simulate experiments. Model results and measurements are compared. A good agreement is found on the power losses in low-loaded deep-groove ball bearings. [ABSTRACT FROM AUTHOR]

Capturing internal flow experimentally presents significant challenges due to the asymmetric propagation and strong unsteadiness of a stall cell in the circumferential direction. In this study, a low-speed counter-rotating axial compressor test rig was designed based on a counter-rotating compressor to immobilize a stall cell and measure its internal flow characteristics. Determining an appropriate speed ratio that is capable of stabilizing the circumferential position of the stall cell in the counter-rotating compressor enabled visualization measurements to be conducted successfully. The preliminary results demonstrated the successful immobilization of the stall cell using an appropriate rotating speed ratio. Furthermore, the oil flow visualization measurements confirmed the presence of a distinct stall cell structure on the casing wall. This work represents an innovative approach towards immobilizing stall cells in axial compression systems.

Bezpilotní vrtulník SkySpotter 150 je vyvinut firmou Modelárna LIAZ. Testovací zařízení pro převodovky vrtulníku nejsou standartní pracoviště. Je zde pohon provázaný s dynamometrem a axiálním zatěžovacím mechanismem simulujícím zatížení od rotoru na výstupním hřídeli převodovky. Proto je potřeba speciálního pracoviště. Byl navržen měřící řetězec včetně jednotlivých snímačů a konstrukce se speciální orientací dynamometru. Konstrukce má bezpečnostní prvky, které chrání testovací zařízení a její obsluhu. Testovací pracoviště je využito k vývoji nových generací vrtulníku. Dále slouží k ověřování parametrů nových převodovek, ale i k technické diagnostice převodovek při opakovaných kontrolách.

Direct contact heat exchangers can be smaller, cheaper, and have simpler construction than the surface, shell, or tube heat exchangers of the same capacity and can operate in evaporation or condensation modes. For these reasons, they have many practical applications, such as water desalination, heat exchangers in power plants, or chemical engineering devices. This paper presents a comprehensive review of experimental and numerical activities focused on the research about direct condensation processes and testing direct contact condensers on the laboratory scale. Computational Fluid Dynamics (CFD) methods and CFD solvers are the most popular tools in the numerical analysis of direct contact condensers because of the phenomenon's complexity as multiphase turbulent flow with heat transfer and phase change. The presented and developed numerical models must be carefully calibrated and physically validated by experimental results. Results of the experimental campaign in the laboratory scale with the test rig and properly designed measuring apparatus can give detailed qualitative and quantitative results about direct contact condensation processes. In this case, the combination of these two approaches, numerical and experimental investigation, is the comprehensive method to deeply understand the direct contact condensation process. [ABSTRACT FROM AUTHOR]

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• Computational modeling of three-dimensional transient wear of thrust bearings in nuclear main pumps. • Positive and negative effects of the presence of scratches on tilting pad thrust bearings. • Effect of scratch wear on bearing lubrication characteristics during rotor start-up and shutdown. A tilting pad thrust bearing wear model based on computational fluid dynamics has been developed, and the wear model was verified and investigated experimentally based on a self-designed test rig. The results show that the presence of scratches results in an increase in oil film pressure, an elevation of the pad center temperature, and a decrease in the minimum oil film thickness. The number of scratches has a more pronounced effect on the lubrication performance of the pad. The test found that the presence of scratches can contain the abrasive chips, which has some positive significance. During the starting process, the pressure center of each ring gradually shifts towards the center of the pad, demonstrating a radial stretching phenomenon. With a further increase in speed, the overall oil film pressure decreases from the center to the periphery, and the influence of scratches on the oil film pressure distribution gradually decreases. [ABSTRACT FROM AUTHOR]

One test rig comprising two blades and dual under-platform dampers (UPDs) was built to enhance the understanding of the dynamic response behavior of blades with dual UPDs. A turnbuckle was applied to enable the smooth and uninterrupted linear adjustment of the normal load on the dual UPDs. Non-contact vibration-response measurements were achieved through eddy-current displacement sensors. Contact excitation was employed using an electromagnetic exciter to determine the magnitude of the excitation load, which was measured using a force sensor mounted on the excitation rod. A feedback system was established to maintain a constant magnitude of the excitation force throughout the excitation process. The chosen experimental variables include the normal load, the amplitude of the excitation force, the effective contact area, and the position of the damper action. The frequency response function of the blade under various experimental parameters was obtained through frequency sweeping under sinusoidal excitation. The influence of each parameter on the dynamic characteristics of blades was studied. The results demonstrate that the double-layer damping system offers distinct advantages over its single-layer counterpart. The upper damping has a wider frequency-adjustment range and a lower resonance amplitude and takes a larger share of the damping efficiency.

This paper describes the activities related to the design, manufacturing and commissioning of an innovative Hardware-In-the-Loop test rig for linear Power Take-Off testing. The rig is characterised by a fully coupled architecture in which three electro-mechanical units integrating a ballscrew and an electrical machine can actuate on a linear axis, either as motor or generator. A preliminary mechanical design of the test rig was carried out by identifying the most demanding conditions. The electrical and mechanical designs were assessed through a de-risking simulation of the overall test rig set-up, considering faults between the motors and respective power converters. The resulting rig setup includes a structure that embeds the three units, an electrical control panel and a control system. The use of electro-mechanical units increases the flexibility of the setup and simplifies the test of extreme conditions such as maximum output power or actuation force. Moreover, it allows reusing the power produced by the generating devices, thus reducing operational costs of the tests. The control system integrates a real-time hardware-in-the-loop simulation platform, a supervisory control and data acquisition systems. Those offer not only the possibility of easily tuning parameters but also testing new control strategies, operational situations, and failures of a power-take-off system in very realistic conditions.

Reducing energy use and improving engine efficiency is a complex task however to date a continued reduction of lubricant viscosity has proved effective. Reducing viscosity decreases hydrodynamic friction and pumping losses however it can also exacerbate boundary friction losses. Detailed and representative component level experimentation is required to understand the effects of viscosity reduction on friction and opportunity for further optimisation. This paper presents a novel motored reciprocating Tribometer which has been developed to measure the friction between complete cylinder liners and three-piece oil control rings. The system holds individual or multiple rings stationary in a bespoke ring holder and reciprocate the cylinder liner thereby replicates the relative kinematics of the components in service. The new design has many operational advantages to identify and benchmark the individual contribution of oil control ring friction including near total isolation of oil ring-cylinder liner bore conjunction, pure rectilinear motion and use of full components without resorting to split liner/ring geometries. The experimental rig is used to measure friction at the three-piece oil control ring- cylinder liner conjunction when lubricated with two low viscosity lubricants. The results show prevalence of mixed regime lubrication across the speeds, temperatures and lubricants investigated. The oil control ring under investigation is shown to operate in mixed regime lubrication and at cold start the introduction of lower viscosity lubricants such as 0W-8 showed higher level of oil control ring-cylinder liner friction in comparison to the 0W-40. The information and experimental facility are of critical use for engine designers when considering the potential contradictory component efficiency behaviour when moving to ultra-low viscosity lubricants. [ABSTRACT FROM AUTHOR]

Propeller-induced longitudinal vibration resonance in marine propulsion shafting systems causes great harm to the hull structure and is the primary source of shipboard noise. Integrating a friction damper with designed parameters into thrust bearings can prevent these issues. To investigate the performance of the damper-integrated thrust bearing in longitudinal vibration transmission control, an experimental and theoretical study is carried out in a laboratory-assembled test rig, which consists of components similar to the existing marine propulsion system. We developed a prototype of a thrust bearing designed with a friction-damping generation that allows switching from two supporting states, i.e., damper-connected and damper-disconnected states. Furthermore, a nonlinear analysis method for friction dampers is proposed. By this method, the way in which the friction damper changes the dynamic characteristics of the shafting system is analyzed. Based on the test rig, the acceleration frequency response function (AFRF) of the thrust bearing with and without a friction damper is measured. By comparison, the effectiveness of the friction damper is proved. The experimental results show that the friction damper suppresses the shafting longitudinal vibration response in a broadband frequency range and also confirms the stability of the damping effect, which does not change with the shafting rotational speed or static thrust from the propeller. [ABSTRACT FROM AUTHOR]

The combustion of kerosene spray under hot-diluted conditions and conventional conditions was experimentally investigated. By examining flame photographs, chemiluminescence images, and in-field temperature measurements, the separate effect of different variables including oxygen concentration, temperature and velocity of the co-flowing air, fuel flow rate and injection pressure, and eventually the type of spray nozzle on multiple parameters such as flame stability, structure, luminosity, temperature field, and qualitative CH radical distribution, as well as HCO and NO2 with lower precision, in the reaction region, have been studied. It was observed that an increment in injection pressure and co-flow temperature enhances the spray flame stability, while dilution exacerbates it. Also, a solid cone spray pattern with a lower spray angle has better stability than hollow cone ones with a higher spray angle. Moreover, it was noted that liquid fuels, compared to gaseous fuels, require higher preheating temperatures, for the same dilution level, to engender a stable flame. For combustion of spray in conventional conditions, a double-flame structure was observed consisting of a bluish section at the leading edge emerging into a yellowish sooting trail. An increase in co-flow velocity, as well as injection pressure, strengthens the inner flame front, whereas raising the co-flow temperature or diluting the oxidant, deteriorates the inner flame front. In the case of highly preheated air (without dilution), the flame liftoff height is reduced to as close to the atomizer as a few millimeters, forming a single flame structure similar to gaseous flames. In this case, the peak temperature was considerably higher than the conventional combustion, yet the gain was much lower than the preheating level. Combined effects of preheating and dilution alter the spray flame structure in a way that the flame volume is reduced, the temperature field has become more homogeneous, the peak temperature is limited to less than 1500 K, and temperature fluctuations have significantly decreased, seemingly approaching MILD combustion regime conditions. [ABSTRACT FROM AUTHOR]

In aero-engines applications, nozzle geometric parameters have major effects on the lubricating oil to accurately reach target gears or bearings. To investigate the deviation phenomenon of oil jet flow in the lubrication system, the computational fluid dynamics (CFD) technique integrating with the volume of fluid (VOF) method and SST k - ω turbulence model is adopted to deeply understand the flow characteristics of the nozzle. By leveraging this method, the relationship between nozzle geometry, inlet pressure, jet velocity, and jet deviation are firstly analyzed. The results reveal that a higher average velocity and smaller jet deviation can be determined via adjusting the nozzle geometry. Furthermore, a specific test rig, composed of an oil supply system, target system and data collection system, is set up for oil injection test; experimental outlet velocity and mass flow rate of oil passing through the hole on the target plate are monitored and recorded. The experimental findings compare well with numerical results obtained by the CFD method. [ABSTRACT FROM AUTHOR]