Search Results

The Continuously Variable Transmission (CVT) is a widely adopted transmission system. The operation of a CVT is simple, but successfully foretelling the longitudinal motion of a vehicle that utilizes this transmission is sophisticated. As a result, different vehicles taking part in BAJA-SAE competitions were developed using various strategies to model the vehicle’s longitudinal dynamics and CVT operation. This article aims to provide a tool for obtaining a quantitative estimate of the longitudinal performance of a CVT equipped vehicle and for the selection of an optimal drive-train gear ratio for such a vehicle. To this end, this article proposes a novel, relatively simple, and reasonably accurate mathematical approach for modeling the longitudinal motion of a vehicle utilizing a CVT, which was developed by a novel integration of existing vehicle dynamics concepts.

The behavior of flow over an automobile’s body has a large effect on vehicle performance, and automobile manufacturers pay close attention to the minimal of the details that affect the performance of the vehicle. An imbalance of downforce between the front and rear portion of the vehicle can lead to significant performance hindrances. Worldwide efforts have been made by leading automobile manufacturers to achieve maximum balanced downforce using aerodynamic elements of vehicle. One such element is the front splitter. This study aims to analyze the aerodynamic performance of automobile at various splitter overhang lengths using Computational Fluid Dynamics (CFD). For the purpose of analysis, a three-dimensional (3D) CFD study was undertaken in ANSYS Fluent using the realizable k-ε turbulence model, based on the 3D compressible Reynolds-Averaged Navier-Stokes (RANS) equations.

Flow separation is one of the primary causes of increase in form drag in vehicles. This phenomenon is also visible in the case of lightweight vehicles moving at high speed, which greatly affects their aerodynamics. Spherical depressions maybe used to delay the flow separation and decrease drag in such vehicles. This study aims for optimization of aspect ratio (AR) of spherical depressions on hatchback cars. Spherical depressions were created on the bonnet of a generalized light vehicle Computer-Aided Design (CAD) model. The diameter of each spherical depression was set constant at 60 mm, and the center-to-center distance between consecutive spherical depressions is fixed at 90 mm. The AR of spherical depressions was taken as the parameter that was varied in each model. ARs 2, 4, 6, and 8 were considered for the current investigation. Three-dimensional (3D) CFD analyses were then performed on each of these models using a validated computational model.

While riding cycles, cyclists usually experience an aerodynamic drag force. Over the years, there has been a global effort to reduce the aerodynamic drag of a cycle. Fenders affect the aerodynamic drag of a cycle to a large extent, and fender coverage has a pronounced effect on the same. In this article, various fender coverage angles, varying from 60° to 270°, were studied to predict the aerodynamic drag with the help of a validated CFD model in SolidWorks Flow Simulation. The model was based on the Favre-Averaged Navier-Stokes (FANS) equations solved using the k-ɛ model. It was predicted that aerodynamic drag coefficient reduced fender coverage angle up to 135°, and thereafter started increasing. Analyses were carried out at velocities of 6 m/s, 8 m/s and 10 m/s and the results were found to be similar, with a minimum aerodynamic drag coefficient at 135° occurring in all the cases under study.

Drag and lift are the primary aerodynamic forces experienced by automobiles. In competitive automotive racing, the design of inverted wings has been the subject of much research aimed at improving the performance of vehicles. In this direction, the aerodynamic impact of change in maximum camber of the flap element and ground effect in a double-element inverted airfoil was studied. The National Advisory Committee for Aeronautics (NACA) 4412 airfoil was taken as the constant main element. The camber of the flap element was varied from 0% to 9%, while ground clearance was varied from 0.1c to 1.0c. A two-dimensional (2D) Computational Fluid Dynamics (CFD) study was performed using the realizable k-ε turbulence model in ANSYS Fluent 18.2 to analyze the aerodynamic characteristics of the airfoil. Parameters such as drag coefficient, lift coefficient, pressure distribution, and wake flow field were investigated to present the optimum airfoil configuration for high downforce and low drag.

Improving brake cooling has commanded substantial research in the automotive sector, as safety remains paramount in vehicles of which brakes are a crucial component. To prevent problems like brake fade and brake judder, heat dissipation should be maximized from the brakes to limit increasing temperatures. This research is a CFD investigation into the impact of existing wheel center designs on brake cooling through increased cross flow through the wheel. The new study brings together the complete wheel and disc geometries in a single CFD study and directly measures the effect on brake cooling, by implementing more accurately modeled boundary conditions like moving ground to replicate real conditions correctly. It also quantifies the improvement in the cooling rate of the brake disc with a change in wheel design, unlike previous studies. The axial flow discharge was found to be increased to 0.47 m3/min for the suggested design in comparison to 0.04 m3/min for traditional design.

Additive manufacturing has experienced rapid growth over a span of 25 years. Additive manufacturing involves the development of a three-dimensional (3D) object by stacking layer upon layer. Conventional machining techniques involve the removal of material. However, this technique differentiates itself from other techniques by means of addition of the material. The integration of CAD with additive manufacturing has offered the ability to create complex structures. Despite its clear benefits, additive manufacturing suffers from a high initial investment. An average cost of an entry level commercial 3D printer is 600$. A low-cost 3D printer has been designed and built for experimental investigation within a budget of 300$. The paramount process of 3D printing involves a combination of interpreting data from CAD files and controlling the motors using this data. The various design considerations while developing the 3D printer have been discussed.

Vehicle performance is highly dependent on the design and material used. Fairing of a Human Powered Vehicle (HPV) is responsible for the reduction in the aerodynamic drag force and its material determines the overall weight and the top speed of the vehicle. Selection of material for fairings depends on various physical, mechanical and manufacturing properties along with practical considerations like availability of material. Today, an ever-increasing variety of composite materials and polymers are available, each of them possessing their own characteristics, applications, advantages and limitations. Many automotive composites are used for manufacturing fairings. Materials like Carbon fiber, Glass fiber (E glass, S glass), Aramid fiber (Kevlar 29, Kevlar 49) are some of the viable options that have been used in the past for manufacturing fairing of HPVs.

The art and science of thrust vectoring technology has seen a gradual shift towards fluidic thrust vectoring techniques owing to the potential they have to greatly influence the aircraft propulsion systems. The prime motive of developing a fluidic thrust vectoring system has been to reduce the weight of the mechanical thrust vectoring system and to further simplify the configuration. Aircrafts using vectored thrust rely to a lesser extent on aerodynamic control surfaces such as ailerons or elevator to perform various maneuvers and turns than conventional-engine aircrafts and thus have a greater advantage in combat situations. Fluidic thrust vectoring systems manipulate the primary exhaust flow with a secondary air stream which is typically bled from the engine compressor or fan. This causes the compressor operating curve to shift from the optimum condition, allowing the optimization of engine performance. These systems make both pitch and yaw vectoring possible.

The Aerofoil theory along with its design has integrated itself into the vast areas of applications ranging from Automobile, Aeronautical, Wind Turbine, Micro-Vehicles, UAVs applications. In this paper, knowing the intricacy of the airfoil's applications, A MATLAB Code for NACA-2415 Airfoil is developed and a Model with dimensions c=180mm, w=126mm, tmax=27mm is generated. The model is then subjected to Flow Simulation with various input parameters: Reynolds Numbers taken are- (REN-1) 105 and (REN-2) 2×105 [Laminar External Flow], Angles of attack taken are-0°, 4°, 8°, 12°. The pressure and velocity distribution along the airfoil sketch curve are graphed qualitatively, emphasizing on the flow separation leading to the transition from laminar to turbulent flow. The various aerodynamics characteristic curves for coefficient of pressure, coefficient of lift and coefficient of drag are plotted against different angle of attacks for REN-1 and REN-2.

At present, vast numbers of problems are triggered due to growing global energy crisis and rising energy costs. Since, on-road vehicles constitute the majority share of transportation; any energy losses in them will have a direct effect on the overall global energy scenario. Most of the energy lost is dissipated from the exhaust, cooling, and lubrication systems, and, most importantly, in the braking system. About 6% of the total energy produced is lost with the airstream in form of heat energy when brakes are applied. Thus, various technological systems need to be developed to conserve energy by minimize energy losses while application of brakes. Regenerative Braking is one such system or an energy recovery mechanism causing the vehicle to decelerate by converting its kinetic energy into another form (usually electricity), which further can be used either immediately or stored until needed.

This paper presents a CFD analysis for drag reduction of a Class 8 Tractor-Trailer arrangement. A three dimensional bluff body model of the truck is simulated for a zero degree yaw angle at a speed of 50 miles per hour for a Reynolds Number of 3.3 million. In this paper, the role of vortex generators is investigated for overall drag reduction of the body. The key areas of interest for lowering the drag coefficient are the tractor-trailer gap and the trailer end. The designing of the body was done on DS SolidWorks whereas the CFD simulations were performed on commercial software Ansys Fluent. The Standard k-ε turbulence model was chosen for the simulation while the convergence criterion for the residuals was set at 10−6. The simple bluff body showed a drag coefficient of 1.654. The first design iteration involved increasing the tractor frontal area which resulted in a reduction of 4% in the drag coefficient.