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The advancement of Advanced Driver Assistance System (ADAS) technologies offers tremendous benefits. ADAS features such as emergency braking, blind-spot monitoring, lane departure warning, adaptive cruise control, etc., are promising to lower on-road accident rates and severity. With a common goal for the automotive industry to achieve higher levels of autonomy, maintaining ADAS sensor performance and reliability is the core to ensuring adequate ADAS functionality. Currently, the challenges faced by ADAS sensors include performance degradation in adverse weather conditions and a lack of controlled evaluation methods. Outdoor testing encounters repeatability issues, while indoor testing with a stationary vehicle lacks realistic conditions. This study proposes a hybrid method to combine the advantages of both outdoor and indoor testing approaches in a Drive-thru Climate Tunnel (DCT). The proposed DCT features a test section that is isolated from the surrounding environment and allows a vehicle to move through a volume of precisely simulated precipitation. It is constructed as a model scale prototype for concept demonstration and preliminary studies. In addition, the DCT’s modular design allows for varying distances, vehicle speeds, and precipitation rates during testing. The model vehicle is equipped with common ADAS sensors, such as optical cameras and LiDARs, which are known to be heavily affected by adverse weather. Quantification metrics are designed and applied to ADAS datasets to investigate sensor performance in conjunction with related phenomena, such as the perceived rain characteristics of a moving vehicle. Therefore, the DCT provides a platform to bridge the gap between outdoor and indoor weather testing for ADAS sensors and open opportunities for sensor perception developments.

This review investigates the nature-inspired techniques for the optimization of the aerodynamic forces on bluff bodies. To provide a rich understanding of these nature-inspired phenomena, three distinct zones of the species fishes (nektons), birds (avians) and the fast running land animals are considered. This allows contextualizing different capabilities of the species in different environmental necessities. The review follows a trend in which drag reduction capabilities of individual parts of these species, including body shape & size, tails, fins, surface structure, wings, and wingtips, have been explored in detail. By focusing on specific parts, the review examined the methods and physics involved, which provides space to narrate the development of ideas and our current understanding of the nature-inspired drag reduction and their application to bluff body aerodynamics. Consequently, nature-inspired promising areas for future endeavor related to the bluff body has been discussed in detail. It was found that, though, aerospace field has found several bird inspired application but the bluff body flow modification have only few. Similar is the case with fishes and land animals which have not been explored yet for aerodynamic use on the bluff bodies. The crucial importance of passive devices are also highlighted along with the review of their application on the bluff bodies inspired by nature. Furthermore, several of nature-inspired techniques are proposed and compared to facilitate the research in this direction. It provides a fundamental method to develop nature-inspired flow control devices for the bluff bodies.

There is a need for fuel-efficient vehicles to reduce greenhouse emission and minimize the range problem of electric vehicles. Aerodynamic drag reduction provides one of the cheapest but effective alternatives. Therefore, the development and analysis of new passive strategies that can modify the flow structure to improve aerodynamic performance are much needed. The present study aims to provide a passive drag reduction method using the standard 35° Ahmed body. The classic rectangular slanted surface is replaced with elliptical to study the effect of reear geometry on aerodynamic performance. The study is conducted using the ANSYS FLUENT software at a Reynolds number of 7.8 × 105, based on the height of the model. The SST k-omega model is applied to solve the Navier-Stokes equations. The results show that the elliptical model reduced the drag by 10% compared to the classic rectangular geometry. The cause of this drag reduction is associated with the large modification of the flow structure in the wake region. Also, the reverse flow is observed to shift towards the vertical base compared to the standard model, where it exits away from the vertical base. The drag reduction is found to correlated with the recirculation modification. Therefore, this study provides detailed data and analysis of wake modification and drag reduction processes.

Studies on the Ahmed body with varying slant angles remain an interesting topic, especially analyses of the flow structures and the corresponding changes in aerodynamic drag and lift in the region 25° ≤ α ≤ 30°, which are not fully understood. Physical insights in the aerodynamic performance of a simplified geometry such as the Ahmed body can improve the geometric optimization of road vehicles for fuel economy improvement. Therefore, this paper examines the three-dimensional wake dynamics of a 28° slanted Ahmed body and proposes a flow control method for its drag reduction. This slanted angle is rarely reported in the open literature. The study is conducted by applying the improved delayed detached eddy simulation (IDDES) using the SST k-ω turbulence model to solve the Navier-Stokes equations at a low Reynolds number of 1.4 × 104 based on the model height. The results reveal a flow separation at the slant surface and reattachment at the rear leading to a secondary separation. A small reverse flow develops after the first separation over the slant surface. Similarly, another minor reverse flow region is concentrated in the middle of the vertical base. However, the flow control method modifies the flow structures similar to the low-drag regime Ahmed body. The aspect ratio of the recirculation region is increased, and the reattachment at the rear end vanishes. Consequently, even at the low Reynolds number studied here, the drag is reduced by up 11%. In addition, the study employs both the time-averaged and time-resolved turbulence statistics and vortex identification methods to provide physical insights into flow modifications and drag reduction. Hence, the paper provides additional valuable information on the flow structure at low Reynolds number to the body of knowledge.

This comprehensive review paper compares the different methods developed experimentally to produce hydrogen by reacting aluminum and water. The alumina oxide layer which forms on the exterior surfa...

This paper reports a numerical investigation of the effect of aspect ratio (AR) on the flow structure around the 35° Ahmed body. The AR is defined as the ratio of length to the height of the model....

Numerical and an experimental study of a soft impact-based piezoelectric energy harvesting system employing a thin layer of magnetorheological (MR) fluid as the impact object is presented in this paper. MR fluid devices are mostly used as vibration suppressors in automobiles and other machinery. MR fluids exhibit variable rheological properties in the presence of a magnetic field, which makes them excellent vibration attenuation devices with easily adaptable damping forces. This behavior can be exploited in vibration energy harvesting to aid frequency up-conversion. The study is carried by solving the theoretical equations numerically and then validating the results experimentally. The Heaviside function is used to model the piecewise nonlinear dynamics of the proposed system. In this way, the sticky and inelastic behavior of the fluid, which causes a time-delay in the oscillations of the beam is best described. The results obtained indicated that increasing the magnetic field increases the voltage generated through frequency amplification. The voltage obtained with a load resistance of 200 k $\Omega $ increased from 9.29 V to 9.42 V when the magnetic field increases from 0.04T to 0.08T for the numerical study and 7.71 V to 8.46 V when the field increased from 0.044T to 0.085T in the experimental study. The frequency is amplified from 59.58 Hz at 0.04T to 82.76 Hz at 0.08T for the numerical results and from 61.02 Hz at 0.044T to 83.04 at 0.085T for the experimental results. The MR fluid acts as a soft impact object in this work.

This paper proposes a new concept using magnetorheological fluids (MRF) as an impacting object or stopper for frequency tuning and power enhancement for a vibrating piezoelectric bimorph cantilever...

This study reported a novel hydrogen production experimental set up, which utilizes the chemical reaction between aluminum and water to produce hydrogen. The developed experimental setup had an aluminum powder spraying subsystem integrated within the overall setup. The effectiveness of this hydrogen production experimental set up was improved using 149-μm aluminum powder, and nitrogen gas as the medium to facilitate the spraying of the aluminum powder. Furthermore, the study utilized sodium hydroxide as the reaction promoter. The various experimental conditions implemented during the testing process included changes in the water temperature and system inputs. The criteria used to evaluate the system performance were the hydrogen yield and hydrogen production rate. The tap water was able to achieve a full hydrogen yield due to its composition, however, the 50% increase in NaOH mass trial was able to achieve a higher yield of 97.15% and 95.44% for the 3g and 6g aluminum sample test respectively. Furthermore, seawater was found to achieve a yield of 58.8%, which can be considered a viable option for future testing. Furthermore, seawater's abundance also adds to its viability for future testing. Also, the study results showed that an increase in reaction temperature best facilitates a chemical reaction taking place. This was evident during the staring temperature of the water test for the 6g aluminum samples. For instance, the maximum hydrogen production rate for the 70 °C was 35.04 mL/s, while the smallest peak for hydrogen production rate was observed using the 40 °C as the starting temperature. The 40 °C test produced a maximum hydrogen production rate value of 27.99 mL/s.

The development of vibration control with smart fluids within flexible structures has been of significant interest in recent times. Although much research has been done on structures with embedded electrorheological fluids (ERF) and magnetorheological fluids (MRF), there has been a little investigation into localizing smart fluids under micro-structures. Research into the damping of micro-structures using ERF is very limited. The research in this article presented a comprehensive study into the controllability of the vibration characteristics of a micro-piezoelectric transducer with ERF support. This structure is made from piezoelectric material with a layer of ERF localized at the tip micro-cantilever beam (MCB). The structural behaviour of the MCB-ERF is alternated by applying an external electric field to activate the ERF. The MCB-ERF was tested under different electric field configurations ranging from 0kV/mm-2kV/mm. The effects of the activation of the ERF were outlined based on the results obtained. The increase in the frequency of MCB as the applied electric field to the ERF increased at 12.4 % experimentally with an electric field of 2kV/mm. The simulation and the analytical results, on the other hand, showed an increase in the frequency of the MCB from 16.2% and 13.46% respectively. The results demonstrated that the stiffness and damping structural characteristics of the MCB are controlled. This confirms the vibration controlling capabilities of MCB-ERF as structural elements.

The emergence of autonomous driving technology has tremendous mobility and social-economic benefits. Autonomous vehicles (AVs) rely on various sensors for environmental and traffic data. However, the sensor performance and reliability degrade in adverse weather conditions, which poses a challenge to the safety of AVs. Existing active mitigation strategies such as wipers and water jets are active, complex, and expensive to implement. This study investigated soiling mitigation via a passively rotating lens with the goal to maintain Advanced-Driver-Assistance-System (ADAS) sensor visibility in the rain. The concept of rotating lens has merely been lightly explored in the literature but never studied in detail with realistic continuous rain simulation to verify soiling mitigation effectiveness. An optical camera in place of a frontal vehicle ADAS sensor was integrated into a rotating lens for visual characterization. A wind tunnel was used to simulate various wind-driven rain scenarios in both urban and suburban driving speeds. As driving speed in rain increases, sensor reliability and performance exacerbate due to an increase in perceived rain characteristics, including angle and intensity. This investigation studied the correlation of the rotating lens angular velocity at different driving speeds and its effectiveness in mitigating soiling under various perceived rain conditions. The increase in angular velocity resulted in a direct increase in centrifugal force experienced by each raindrop present on the lens; hence, providing a mitigation effect when droplets are spun off. Compared to stationary reference lens, observations from mitigation-enabling rotating lens showed greatly improved clarity from the optical camera frontal view in reduction of environment obstruction and distortion from rain droplets. Image processing results suggested high confidence in combating all droplet sizes and driving-in-rain conditions. This investigation successfully demonstrated the effectiveness of rotating lens as a concept for soiling mitigation and provided insight for enhancing ADAS sensor performance and reliability in adverse weather conditions.

The standard Ahmed body (SAB) with a rectangular rear end is a simplified, canonical bluff body geometry that shares similarities with generic road vehicles. It is known to produce flow separations and strong vortices at the rear end. The aerodynamic performance of vehicles is significantly affected by such three-dimensional flow structures. This work proposed a modified Ahmed body with an elliptical rear end called the elliptical Ahmed body. The study examines in detail the near-field characteristics of the flow over the elliptical Ahmed body at a slant angle of 25° with a low Reynolds number of [Formula: see text] based on the model height. The principal flow features are analyzed using time-resolved and standard particle image velocimetry. The time-averaged and time-resolved analyses revealed a fully detached flow at the rear end that eliminated the slant separation bubble. Furthermore, a significant wake flow restructuring is found to curb the lower recirculation bubble and shift the upper recirculation bubble toward the slant surface. Thus, the elliptical curvature shifts the critical slant angle of 30° in SAB to 25°, which indicates transformation of the high-drag flow structures into low-drag. Several distinct Strouhal numbers are found over the slant surface (St = 0.55–0.88), which are higher than that of the SAB, while no significant change is found in the wake region (St = 0.23–0.50). In addition, the effect on coherent structures is evaluated using proper orthogonal decomposition and dynamic mode decomposition, which shows a considerable difference between the standard and elliptical Ahmed body wake structures. The results of this investigation show that body modification of the Ahmed body using elliptical curvature at the rear end can significantly affect the overall flow features and help improve the aerodynamic performance of the vehicles.

This paper performed analyses on a proposed direct wind-powered heat pump integrated with a pond which serves as an evaporator for space heating in cold regions. The analysis was conducted using environmental data for selected locations in Canada and the engineering equation solver (EES). Three different pairings of heat pumps and wind turbines were studied (a wind-powered heat pump with a pond as an evaporator, wind-powered heat pump without a pond, and an electricity-powered heat pump (EPHP)). Energy and exergy analyses were performed on the systems. The novelty in the present study is in the use of a wind turbine to directly power the heat pump and using a pond as the evaporator. The results show that the proposed system has the highest coefficient of performance (COP) compared with the others. The average coefficient of performance for the selected locations is 2.7, which is at least 67% better than the others. Similarly, the overall exergy for the proposed system is 16.9%, which is at least 40% better than the others. The average heating capacity of the selected locations for the proposed system is 4.5 kW, which is from 29% to 300% better than the others. Additionally, the sustainability index (SI) for the proposed system is the highest for the proposed system. The results have shown that the proposed system has superior overall performance for space heating in cold regions.

Observations and prediction of extreme weather (Wx) conditions are important for land, air and sea or water transportation applications. These conditions adversely affect the economic and social life of people. Extreme Wx conditions for aviation operations for example, include, gust (Ug), wind (Uh), and turbulence (U’), low visibility (Vis), fog and frost, and icing as well as heavy precipitation. These conditions can be studied either in the natural atmosphere or in the laboratory. There have been several aircraft and balloon based in-situ studies related to extreme Wx conditions affecting aviation operations. However, studying extreme Wx conditions from aircraft observations is limited due to safety and sampling issues, instrument uncertainties, and even the possibility of the aircraft producing its own physical and dynamical effects. Remote sensing-based techniques (e.g., retrieval techniques) for studying extreme Wx conditions usually represent a volume that cannot characterize the important scales, and also represents indirect observations. Therefore, climatic wind tunnel simulations of atmospheric processes together with field observations can help us to better evaluate the interactions among microphysical and dynamical processes affecting extreme Wx conditions e.g., cold air temperatures (Ta) and low/high relative humidity with respect to water (RHw). The Climatic Wind Tunnel (CWT) in the Automotive Centre of Excellence (ACE) at the Ontario Tech University has a large semi-open jet test chamber with a flow area of 7-13 m2 that can precisely control Ta down to -40ºC, and Uh up to 250 km hr-1. Ice and liquid phases of particle size distributions n the CWT are measured with optical probes such as GCIP, CDP, BCP, FMD, and LPM probes (Gultepe et al 2019, PAAG). The ACE CWT employs several modes of generating sprays, including a spray nozzle array suspended in its settling chamber and fed by heated pressurized de-ionized water to create supercooled droplets, a snow gun also located in the settling chamber, and a spray rig at the nozzle exit, to create a wide range of particle sizes from a few µm up to mm size range to create extreme Wx conditions. These set-ups, together with a range of cold Ta and RHw, plus a wide range of Uh, enabled simulation of severe Wx conditions, including icing, Vis, strong Uh and U’, ice fog and frost, freezing fog, heavy snow, and blizzard conditions. Overall, the results from the CWT simulations supported by the Ontario Tech University AViation MEteorological Supersite (AVMES) observations will be summarized for the aviation operations representing cold environments.

A cascade heat pump is proposed as an environmentally friendly alternative to natural gas heating systems used for space heating in the residential sector. A comparative life cycle assessment of a natural gas furnace and a cascade heat pump was conducted to show the reductions in environmental impacts, such as global warming potential, energy used, and cost savings. The analysis used environmental data from 2020 for Toronto, Ontario, Engineering Equation Solver, and Sustainable Minds. The results of this comparative assessment demonstrate that implementing a cascade heat pump for heating purposes reduces the global warming potential by 85.4% when compared to a typical natural gas furnace. Moreover, the negative impacts on human health are reduced in every category. Specifically, the factors that can cause harm to human respiratory systems are decreased by almost 10 times when using the cascade heat pump as an alternative heating system. This is important since such systems are used in high density residential areas where the impact on human health can be far greater. Lastly, it is found that the highest CO2 -equivalent emissions are released during the usage life cycle stage in both heating systems at 18 883 kg of CO2 -equivalent, and 104 CO2 -equivalent for the furnace and heat pump, respectively. The cascade heat pump releases approximately 1% of carbon emissions than the emissions released by currently used heating systems, which are natural gas furnaces. Integr Environ Assess Manag 2021;00:1-9. © 2021 SETAC.

Efficient, economic and environmentally friendly aircrafts and their operations have become the focus of research nowadays after the COVID-19 pandemic has spread around the world. This paper presents a combined solid oxide fuel cell with a turbofan engine system in order to improve the efficiency, cost and environmental performance. Two different analyses were conducted through analyses covering exergy and exergoeconomic aspects. Also, the paper investigates five alternative fuels with five fuel blends on the system performance. It is founded that the overall exergetic performance is the same among the five fuel blends of 82% exergetic efficiency and 18% exergy destruction ratio. In addition, using the methanol and hydrogen fuel blend appears to be the most economic way of achieving a relative cost difference of 38% and minimum price of electricity generation in the range of 108 to 621 $/GJ for turbines and SOFC. However, using dimethyl ether and hydrogen fuel blend becomes less favorable.