A CFD Simulation Approach for Optimizing Front Air-Dam to Improve Aerodynamic Drag of a Vehicle

2020 ◽  
Author(s):  
Subramaniyan Baskar ◽  
Nagarajan Gopinathan
Keyword(s):  
Cfd Simulation ◽  
Aerodynamic Drag ◽  
Simulation Approach

scholarly journals CFD Simulation of a Hyperloop Capsule Inside a Low-Pressure Environment Using an Aerodynamic Compressor as Propulsion and Drag Reduction Method

2021 ◽  
Vol 11 (9) ◽  
pp. 3934
Author(s):  
Federico Lluesma-Rodríguez ◽  
Temoatzin González ◽  
Sergio Hoyas
Keyword(s):  
Shock Waves ◽  
Power Consumption ◽  
High Speed ◽  
Cfd Simulation ◽  
Aerodynamic Drag ◽  
Flow Behavior ◽  
Critical Conditions ◽  
Vehicle Speed ◽  
Blockage Ratio ◽  
The Cost

One of the most restrictive conditions in ground transportation at high speeds is aerodynamic drag. This is even more problematic when running inside a tunnel, where compressible phenomena such as wave propagation, shock waves, or flow blocking can happen. Considering Evacuated-Tube Trains (ETTs) or hyperloops, these effects appear during the whole route, as they always operate in a closed environment. Then, one of the concerns is the size of the tunnel, as it directly affects the cost of the infrastructure. When the tube size decreases with a constant section of the vehicle, the power consumption increases exponentially, as the Kantrowitz limit is surpassed. This can be mitigated when adding a compressor to the vehicle as a means of propulsion. The turbomachinery increases the pressure of part of the air faced by the vehicle, thus delaying the critical conditions on surrounding flow. With tunnels using a blockage ratio of 0.5 or higher, the reported reduction in the power consumption is 70%. Additionally, the induced pressure in front of the capsule became a negligible effect. The analysis of the flow shows that the compressor can remove the shock waves downstream and thus allows operation above the Kantrowitz limit. Actually, for a vehicle speed of 700 km/h, the case without a compressor reaches critical conditions at a blockage ratio of 0.18, which is a tunnel even smaller than those used for High-Speed Rails (0.23). When aerodynamic propulsion is used, sonic Mach numbers are reached above a blockage ratio of 0.5. A direct effect is that cases with turbomachinery can operate in tunnels with blockage ratios even 2.8 times higher than the non-compressor cases, enabling a considerable reduction in the size of the tunnel without affecting the performance. This work, after conducting bibliographic research, presents the geometry, mesh, and setup. Later, results for the flow without compressor are shown. Finally, it is discussed how the addition of the compressor improves the flow behavior and power consumption of the case.

On the RANS Modeling of Turbulent Airflow Over a Simplified Car Model

2011 ◽  
Author(s):  
G. Bella ◽  
V. K. Krastev
Keyword(s):  
Cfd Simulation ◽  
Aerodynamic Drag ◽  
Cooling System ◽  
Experimental Studies ◽  
System Optimization ◽  
Wake Flow ◽  
Car Model ◽  
Numerical Predictions ◽  
Light Duty Vehicle ◽  
Ahmed Body

The need for reliable CFD simulation tools is a key factor for today’s automotive industry, especially for what concerns aerodynamic design driven by critical factors such as the engine cooling system optimization and the reduction of drag forces, both limited by continuously changing stylistic constraints. The Ahmed body [1] is a simplified car model nowadays largely accepted as a test-case prototype of a modern passenger car because in its aerodynamic behavior is possible to recognize many of the typical features of a light duty vehicle. Several previous works have pointed out that the flow region which presents the major contribution to the overall aerodynamic drag, and which presents severe problems to numerical predictions and experimental studies as well, is the wake flow behind the vehicle model. In particular, a more exact simulation of the wake and separation process seems to be essential for the accuracy of drag predictions. In this paper a numerical investigation of flow around the Ahmed body, performed with the open-source CFD toolbox OpenFOAM®, is presented. Two different slant rear angle configurations have been considered and several RANS turbulence models, as well as different wall treatments, have been implemented on a hybrid unstructured computational grid. Pressure drag predictions and other flow features, especially in terms of flow structures and velocity field in the wake region, have been critically compared with the experimental data available in the literature and with some prior RANS-based numerical studies.

Numerical Optimization Research on Rear Characteristic Angles Based on MIRA Model for Aerodynamic Drag Reduction

2013 ◽  
Vol 774-776 ◽  
pp. 428-432
Author(s):  
Qian Qian Du ◽  
Xing Jun Hu ◽  
Qi Fei Li ◽  
Yu Kun Liu ◽  
Bo Yang
Keyword(s):  
Inclination Angle ◽  
Numerical Optimization ◽  
Cfd Simulation ◽  
Aerodynamic Drag ◽  
Optimization Method ◽  
Aerodynamic Design ◽  
Rear Window ◽  
Passenger Car ◽  
Two Parameters ◽  
Aerodynamic Drag Reduction

The rear characteristic angles of the passenger car in this study were defined as the inclination angle of rear window and the bottom inclination angle of aft based on the MIRA model. The numerical optimization method was used to analyze the influence of combined variation of two angles on the external flow field and the CD of the passenger car, in which we combined genetic algorithm with the CFD simulation to reduce aerodynamic drag by seeking the relatively optimal combination of two parameters above. The study reveals that when the combination of the inclination angle of rear window and bottom inclination angle of aft is 25oand 0.067o, the total pressure and streamline distribution in the flow fields of the MIRA model are improved greatly and the CD is reduced compared with the worst combination. This conclusion will have profound guiding significance in the aerodynamic design of the rear styling and shape of a car.

CFD Simulation Approach for Semisubmersible Response in Waves Based on Advanced Techniques

2015 ◽  
Vol 772 ◽  
pp. 108-113 ◽  
Author(s):  
Ionuț Cristian Scurtu
Keyword(s):  
Cfd Simulation ◽  
Simulation Approach ◽  
Floating Structures ◽  
Sea Currents

All floating structures react different to sea currents and waves and the commonly asked question is how to understand, simplify and make distinction of structure according to the operational challenges. The main objective of this paper is to determine the response of a three column semisubmersible platform as used by WindFloat project with available CFD software: CFX and Fluent. The WindFloat created by PowerPrinciple is presented and the present study will consider only the semisubmersible.

scholarly journals Drag Reduction on car side mirrors with the implementation of camera modules

2021 ◽  
Author(s):  
Mahmud Hasan ◽  
Jeffrey Yokota
Keyword(s):  
Solid State ◽  
Drag Reduction ◽  
Cfd Simulation ◽  
Aerodynamic Drag ◽  
The Other ◽  
Aerodynamic Forces ◽  
Fuel Prices ◽  
Entire Vehicle ◽  
Maximum Decrease ◽  
Total Vehicle

The greatest obstacle in the acceleration of a car through air is aerodynamic drag. With this increased drag is the expenditure of fuel. About 50-60% of a vehicles’ total fuel energy is lost to overcome adverse aerodynamic forces. However, with the increase of fuel prices, many solutions have surfaced. One of these solutions are the implementation of camera modules to replace bulky traditional side mirrors. For this report, a thorough analysis was conducted into the aerodynamic benefits of these newly proposed camera modules in comparison to the conventional solid state mirrors. Specifically, one conventional side mirror along with two newly proposed camera module’s were studied in this thesis report. For this analysis, the overall drag of each module was found using CFD simulation under turbulent conditions at 60 km/h using the Realized K- method. The drag and Cd values found for the conventional side mirror were 3.985 N and 0.38 respectively. The values found for the two camera modules, Models B and C, were 0.526 N and 0.857 N. Their Cd values were found to be 0.312 and 0.365. This shows a potential of the drag reduction of the side mirror by almost 87% if the switch was made to the newer technology. This value also agreed with the prediction by Honda on their technology which has stated a possible drag reduction for this part by up to 90%. However, when observing the bigger picture, it became evident that although this drag reduction is significant for locally, it simply is not enough to make a big impact on the drag reduction of the entire vehicle. With a maximum decrease in the total vehicle drag found to to be only 4%, the reduction in the fuel consumption of the vehicle would only decrease by 0.2 gallons per mile. On the other hand, improvements in parts such as the car rims or the underbelly of the car can result in fuel improvements of upwards of 12%-25%. For this reason, it can be concluded that automobile manufacturers research other possible solutions to reduce the vehicle drag such as with the redesign of the underbelly of the car or wheel arches and rims.

Investigation on the Aerodynamic Efficiency of Braking Spoiler for High Speed Train Applications

2020 ◽  
pp. 2150009
Author(s):  
M. Vikraman ◽  
J. Bruce Ralphin Rose ◽  
S. Ganesh Natarajan
Keyword(s):  
High Speed ◽  
Cfd Simulation ◽  
Aerodynamic Drag ◽  
High Speed Train ◽  
Passenger Cars ◽  
High Speed Rail ◽  
Braking Performance ◽  
Simulation Tools ◽  
Drag Forces ◽  
Differential Drag

The demand for high speed rail networks is rapidly increasing in developing countries like India. One of the major constraints in the design and implementation of high speed train is the braking efficiency with minimum friction losses. Recently, the aerodynamic braking concept has received good attention and it has been incorporated for high speed bullet trains as a testing phase. The braking performance is extremely important to ensure the passenger safety specifically for the trains moving at more than 120[Formula: see text]km/h. In this paper, an Indian train configuration WAP7 (wide gauge AC electric passenger, Class 7) has been assumed with the locomotive and one passenger car. Aerodynamic braking system design is done by opening a spoiler over the train to amplify the aerodynamic drag at high speeds. The magnitude of braking force depends on the position and orientation of the braking spoiler. It creates differential drag forces at various deflection angles to decelerate the trains instantaneously in proportion to the running speeds. Drag created by the braking spoiler is observed numerically with the help of CFD simulation tools for further validation through wind tunnel experiments. Striking aerodynamic results are obtained with and without braking spoilers on the passenger cars and the spoiler at 40[Formula: see text]–50[Formula: see text] orientation makes greater drag coefficient as compared to the other angles.

A Comparison of 1D-3D Co-Simulation and Transient 3D Simulation for EGR Distribution Studies

2016 ◽  
Author(s):  
P. Dimitriou ◽  
C. Avola ◽  
R. Burke ◽  
C. Copeland ◽  
N. Turner
Keyword(s):  
Cfd Simulation ◽  
Simulation Software ◽  
Experimental Results ◽  
3D Simulation ◽  
Convergence Time ◽  
Simulation Approach ◽  
Mesh Quality ◽  
Time Step ◽  
1D Model ◽  
Simulation Time

Computational modeling, an important task for design, research and development stages, is evolving fast with the increase of computational capabilities over the last decades. One-dimensional (1D) CFD simulation is commonly used to analyze the flow rates and pressures of an entire fluid system of interconnected parts such as pipes, junctions, valves, and pumps. In contrast, three-dimensional (3D) CFD simulation allows detailed modeling of components such as manifolds, heat exchangers, and combustion cylinders where the flow contains significant 3D effects. Coupling a 1D model with a 3D domain potentially offers the benefits of both simulation strategies in one co-simulation approach. The present study provides a deep understanding of the co-simulation approach by listing all necessary steps need to be followed before and during the coupling of the 1D and 3D simulation software. It analyses the simulation and convergence time requirements based on the 3D model mesh quality and compares this approach with the current 1D–3D uncoupled approach followed in the industry. The outputs of both simulation approaches are then compared with experimental results. The co-simulation time mainly depends on the mesh quality of the 3D domain and the number of inner iterations per time-step which is entirely determined by the nature and complexity of the simulation. The co-simulation time per engine cycle is almost identical to the uncoupled approach. However, it was found that the number of cycles required for convergence in the coupled approach is nearly double than the uncoupled approach. The comparison between the two simulation approaches and the experimental results demonstrated the very 3D nature of the flows, the sensitivity of the uncoupled approach to input conditions and the sensitivity of co-simulation to the averaged boundary conditions transferred from the 1D model back to the 3D domain.

scholarly journals Drag Reduction on car side mirrors with the implementation of camera modules

2021 ◽  
Author(s):  
Mahmud Hasan ◽  
Jeffrey Yokota
Keyword(s):  
Solid State ◽  
Drag Reduction ◽  
Cfd Simulation ◽  
Aerodynamic Drag ◽  
The Other ◽  
Aerodynamic Forces ◽  
Fuel Prices ◽  
Entire Vehicle ◽  
Maximum Decrease ◽  
Total Vehicle

The greatest obstacle in the acceleration of a car through air is aerodynamic drag. With this increased drag is the expenditure of fuel. About 50-60% of a vehicles’ total fuel energy is lost to overcome adverse aerodynamic forces. However, with the increase of fuel prices, many solutions have surfaced. One of these solutions are the implementation of camera modules to replace bulky traditional side mirrors. For this report, a thorough analysis was conducted into the aerodynamic benefits of these newly proposed camera modules in comparison to the conventional solid state mirrors. Specifically, one conventional side mirror along with two newly proposed camera module’s were studied in this thesis report. For this analysis, the overall drag of each module was found using CFD simulation under turbulent conditions at 60 km/h using the Realized K- method. The drag and Cd values found for the conventional side mirror were 3.985 N and 0.38 respectively. The values found for the two camera modules, Models B and C, were 0.526 N and 0.857 N. Their Cd values were found to be 0.312 and 0.365. This shows a potential of the drag reduction of the side mirror by almost 87% if the switch was made to the newer technology. This value also agreed with the prediction by Honda on their technology which has stated a possible drag reduction for this part by up to 90%. However, when observing the bigger picture, it became evident that although this drag reduction is significant for locally, it simply is not enough to make a big impact on the drag reduction of the entire vehicle. With a maximum decrease in the total vehicle drag found to to be only 4%, the reduction in the fuel consumption of the vehicle would only decrease by 0.2 gallons per mile. On the other hand, improvements in parts such as the car rims or the underbelly of the car can result in fuel improvements of upwards of 12%-25%. For this reason, it can be concluded that automobile manufacturers research other possible solutions to reduce the vehicle drag such as with the redesign of the underbelly of the car or wheel arches and rims.

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