The increasing demand for electric mobility has brought about significant advancements in tyre design. This paper covers the latest developments in tyre design that cater specifically to the needs of electric vehicles (EVs). EVs have unique performance characteristics that place greater emphasis on tyre requirements like High traction, Wear resistance, Low Cavity & pattern noise, Low Rolling resistance and High load carrying capacity. Hence, the tyre manufacturers have been working relentlessly to create advanced designs that can meet these requirements. This paper will cover various aspects of tyre design, including tyre cavity, tread patterns, sidewall design, Compound & reinforcement design, and various construction techniques. The tyre cavity and pattern play a crucial role in the overall performance of an EV. The new tyre cavity with flat tread and adaptive tread pattern are optimized to provide low rolling resistance, pattern noise reduction and enhanced dry and wet traction.
The brass synchronizers are not resilient to abuse conditions of gearbox operations, but they are very durable and cheap when used on their favorable limits of the working boundary. The main failure which can occur in gearbox due to synchronizer is crash noise while gear shifting which will create high discomfort for the driver and have to apply high force to change the gears. The main factors which contribute to the crash phenomenon is insufficient coefficient of friction, high drag in the system, high wear rate of the synchronizer rings before the warranty life of the part. The brass synchronizers were tested on the SSP-180, ZF synchronizer testing rig to know the effect of the main synchronizer performance parameters like coefficient of friction, sleeve force, slipping time as well as durability parameter like wear rate when operating temperature of the oil is changed.
Over the last few years, the Electric Vehicle Market (EV's) has experienced significant growth. One of the major challenges faced by electric vehicles is its tyre performance requirements. Reduced range, Increased vehicle weight, higher motor torque and absence of engine needs lower rolling resistance, higher load capacity, low tread wear & low noise tyre respectively. All these demands will lower the ride comfort performance of the Electric Vehicle. The objective of this work is to investigate the impact of tyre parameters on the ride comfort performance of EV's. Tyre construction, tread compound and tyre pressure have a significant impact on the ride comfort performance. Tests like drive point mobility, modal analysis and cleat test are carried out experimentally as well as using virtual tools, the ride comfort performance of tyres is evaluated. The results shows that tyre construction and inflation pressure have major influence on the ride comfort performance of EV tyres.
Racing and high-performance vehicles utilize their underbody floor and diffuser as efficient mechanisms to generate the majority of their downforce. Previous work has primarily been focused on simplified bluff bodies with plane diffusers. The little published work on more complex multichannel diffusers has shown improved downforce generation over plane diffuser, but with limited understanding of the flow features and their response to ride height. This study analyses the performance and complex flow features of a high-performance vehicle equipped with a multichannel diffuser at various ride heights. A comparative assessment between RANS and DDES simulations is performed, which shows that both models adequately predict downforce and underbody flow features at high to medium ride heights, but only the DDES model is able to capture the unsteady flow behavior, which dominates the diffuser at low ride heights.
Abstract Since the steady-state computational fluid dynamics (CFD) Reynolds-averaged Navier–Stokes (RANS) turbulence models offer low-cost and sensible accuracy, they are frequently utilized for bluff bodies’ external aerodynamics investigations (e.g., upwind, crosswind, and shape optimization). However, no firm certainty is made regarding the best model in terms of accuracy and cost. Based on cost and accuracy aspects, four RANS turbulence models were studied, which are Spalart–Allmaras, realizable k-ε, RNG k-ε, and SST k-ω. Ahmed body with a 25° slant angle benchmark case was introduced for this investigation. Two grids were generated to satisfy the near-wall treatment of each turbulence model. All grid settings were proposed and discussed in detail. Fluid-structure analysis was performed on five different planes.
Turbulent Jet Ignition (TJI) represents one of the most effective solution to improve engine efficiency and to reduce fuel consumption and pollutants emission. Even if active prechambers allow a precise control of the air-fuel ratio close to the spark plug and the ignition of ultra-lean mixtures in the main chamber, passive prechambers represent a more attractive solution especially for passenger cars thanks to their simpler and cheaper configuration, which is easier to integrate into existing engines. The main challenge of passive prechambers is to find a geometry that allows to use TJI in the whole engine map, especially in the low load/speed region, without the use of a second sparkplug in the main chamber. To this end, this works reports a CFD study coupled with an experimental investigation to overcome this limitation.
In the context of reducing carbon-dioxide (CO2) emissions, the increasing exploitation of renewable sources is expected to improve the availability of green hydrogen, which can be considered a valid alternative to gasoline and diesel fuels in the mobility sector (particularly for long-haul and heavy-duty missions). The air-hydrogen mixing plays a significant role, particularly in direct-injection spark-ignition engines. As a matter of fact, the onset of zones featuring an equivalence ratio greater than 0.5 should be avoided, since this would lead to an increased risk of self-ignition and NOx production. The presence of wide ultra-lean volumes (over the lean flammability limit) due to imperfect mixing is negative too, yielding to irregular combustion. Therefore, the calibration of the direct injection timing is a crucial task.
Vehicles with active grille shutter (AGS) systems often have bypass and leakage situations that influence the aerodynamic effectiveness and characteristics of the AGS. Precise knowledge of these characteristics, that is, the functional relationship between drag, cooling airflow rate, and degree of opening of an AGS is a prerequisite for optimum aero-thermodynamic integration into the overall vehicle. However, relatively little is yet known about the interaction of bypass and leakage flows with AGS systems. The present work therefore investigates how a bypass affects the aerodynamic characteristics of AGS. The starting point is a recently developed theory that allows an analytical prediction of the aerodynamic behavior of AGS based on the opening characteristic. This theoretical approach is first extended to the case with bypass and matched against experimental data from a real vehicle with AGS bypass configuration.
The Environmental Protection Agency (EPA), in partnership with Research Triangle Institute (RTI International) and Auto Research Center (ARC-Indy), have created digital geometries of commercially available heavy-duty tractor-trailers. The goal of this effort was to improve the agency’s understanding of aerodynamic modeling of modern trucks and to provide opportunities for more consistent engagement on computational fluid dynamics (CFD) analyses. Sleeper and day cab tractors with aerodynamic features and a 53-foot box trailer with aerodynamic technology options were scanned to create high-resolution geometries. The scanning process consisted of a combination of physical scanning with a handheld device, along with digital post-processing. The completed truck geometries are compatible with most commercial CFD software and are publicly available for modeling and analyses.