Application of RNG k-ε Turbulence Model on Numerical Simulation in Vehicle External Flow Field

2012 ◽  
Vol 170-173 ◽  
pp. 3324-3328 ◽  
Author(s):  
Jing Yu Wang ◽  
Xing Jun Hu
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Turbulence Model ◽  
Aerodynamic Drag ◽  
Wind Tunnel Test ◽  
Turbulence Models ◽  
Aerodynamic Characteristics ◽  
External Flow ◽  
Car Model ◽  
Drag And Lift

The two turbulence models were used to numerically simulate the external flow field around the Ahmed standard car model, and the aerodynamic drag and lift coefficients and aerodynamic characteristics around model were obtained. By comparison between the simulation results and the corresponding wind tunnel test data, the differences of two turbulence models were analyzed. The results indicated the simulation result of RNG k-εturbulence model is more precision, and it is more suitable on numerical simulation in vehicle external flow field. The conclusions provide reference for how to select turbulence model.

Comparative Study on External Flow Simulation of Passenger Car with Complex Underbody and Flat Underbody

2013 ◽  
Vol 380-384 ◽  
pp. 69-72 ◽  
Author(s):  
Xu Yan ◽  
Xin Qiao ◽  
Zhi Ming Zhao ◽  
Jian Ye ◽  
Lei Liao ◽  
...  
Keyword(s):  
Flow Field ◽  
Aerodynamic Drag ◽  
Flow Simulation ◽  
Aerodynamic Characteristics ◽  
External Flow ◽  
Field Structure ◽  
Passenger Car ◽  
Car Model ◽  
Cfd Method ◽  
Aerodynamic Drag Reduction

In this paper, the external flow simulation has been carried out on a simplified passenger car model with two schemes adopted: a smoothed complex underbody and a flat underbody. The aerodynamic characteristics and the flow field structure of the passenger car model were obtained with CFD method, and the drag coefficients of the smoothed complex underbody and the flat underbody are respectively 0.275 and 0.251. According to the simulation, flow separation and energy loss of fluid was caused by protuberances on the complex underbody. As there are many differences between the aerodynamic characteristics of the smoothed underbody and the flat one, its suggested to use a smoothed complex underbody not a flat underbody in the studying of aerodynamic drag reduction of a passenger car.

scholarly journals Numerical Simulation and Analysis of External Flow Field of the Van

2019 ◽  
Vol 293 ◽  
pp. 01001
Author(s):  
Kan Zhou ◽  
Ge Huang ◽  
Bin Liu ◽  
Qi Hu
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Vortex Motion ◽  
Aerodynamic Characteristics ◽  
External Flow ◽  
Calculation Results

This paper uses CFD preprocessing software to build Van model and gridding it, then CFD software is used to simulation the outflow field of Van model, from which the distribution of pressure and velocity is obtained and the outflow field is analyzed. The calculation results indeed reflect the aerodynamic characteristics of the external flow field of the van, and the flow movement on the van surface is better simulated. In addition, the positions where the vortex motion is relatively severe are also found

Experimental Studies on Aerodynamic Characteristics of Pantograph System According to the Pantograph Cover Configurations for High Speed Train

2011 ◽  
Author(s):  
Yeongbin Lee ◽  
Minho Kwak ◽  
Kyu Hong Kim ◽  
Dong-Ho Lee
Keyword(s):  
Wind Tunnel ◽  
High Speed ◽  
Aerodynamic Drag ◽  
Aerodynamic Force ◽  
Experimental Studies ◽  
Wind Tunnel Test ◽  
Aerodynamic Characteristics ◽  
Experimental Models ◽  
High Speed Train ◽  
Drag And Lift

In this study, the aerodynamic characteristics of pantograph system according to the pantograph cover configurations for high speed train were investigated by wind tunnel test. Wind tunnel tests were conducted in the velocity range of 20∼70m/s with scaled experimental pantograph models. The experimental models were 1/4 scaled simplified pantograph system which consists of a double upper arm and a single lower arm with a square cylinder shaped panhead. The experimental model of the pantograph cover is also 1/4 scaled and were made as 4 different configurations. It is laid on the ground plate which modeled on the real roof shape of the Korean high speed train. Using a load cell, the aerodynamic force such as a lift and a drag which were acting on pantograph system were measured and the aerodynamic effects according to the various configurations of pantograph covers were investigated. In addition, the total pressure distributions of the wake regions behind the panhead of the pantograph system were measured to investigate the variations of flow pattern. From the experimental test results, we checked that the flow patterns and the aerodynamic characteristics around the pantograph systems are varied as the pantograph cover configurations. In addition, it is also found that pantograph cover induced to decrease the aerodynamic drag and lift forces. Finally, we proposed the aerodynamic improvement of pantograph cover and pantograph system for high speed train.

Numerical analysis for wake flow field of Ahmed model based on a nonlinear-LRN/DES turbulence model

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Le Dian Zheng ◽  
Yi Yang ◽  
Guang Lin Qiang ◽  
Zhengqi Gu
Keyword(s):  
Experimental Data ◽  
Flow Field ◽  
Reynolds Stress ◽  
Turbulence Model ◽  
Turbulence Models ◽  
Aerodynamic Characteristics ◽  
Wake Flow ◽  
Field Analysis ◽  
Content Type ◽  
Des Model

Purpose This paper aims to propose a precise turbulence model for automobile aerodynamics simulation, which can predict flow separation and reattachment phenomena more accurately. Design/methodology/approach As the results of wake flow simulation with commonly used turbulence models are unsatisfactory, by introducing a nonlinear Reynolds stress term and combining the detached Eddy simulation (DES) model, this paper proposes a nonlinear-low-Reynolds number (LRN)/DES turbulence model. The turbulence model is verified in a backward-facing step case and applied in the flow field analysis of the Ahmed model. Several widely applied turbulence models are compared with the nonlinear-LRN/DES model and the experimental data of the above cases. Findings Compared with the experimental data and several turbulence models, the nonlinear-LRN/DES model gives better agreement with the experiment and can predict the automobile wake flow structures and aerodynamic characteristics more accurately. Research limitations/implications The nonlinear-LRN/DES model proposed in this paper suffers from separation delays when simulating the separation flows above the rear slant of the Ahmed body. Therefore, more factors need to be considered to further improve the accuracy of the model. Practical implications This paper proposes a turbulence model that can more accurately simulate the wake flow field structure of automobiles, which is valuable for improving the calculation accuracy of the aerodynamic characteristics of automobiles. Originality/value Based on the nonlinear eddy viscosity method and the scale resolved simulation, a nonlinear-LRN/DES turbulence model including the nonlinear Reynolds stress terms for separation and reattachment prediction, as well as the wake vortex structure prediction is first proposed.

Influence of Regulating Seam on Aerodynamic Characteristics of Virtual Wind Tunnel

2013 ◽  
Vol 774-776 ◽  
pp. 290-294
Author(s):  
Xing Jun Hu ◽  
Lei Yue
Keyword(s):  
Numerical Simulation ◽  
Wind Tunnel ◽  
Flow Field ◽  
Theoretical Basis ◽  
Aerodynamic Characteristics ◽  
Wind Tunnel Model ◽  
Open Type ◽  
Car Model ◽  
Tunnel Model ◽  
Simulation Results

A digital car model was taken as study object, and the influence of the regulating seam to an open type automobile wind tunnel was discussed by comparing simulation results with test data.The results show that the regulating seam changes the flow field around the collector, reduces the size of unsteady flow field and the flow in test section is uniformed better. Thus, the regulating seam shouldn’t be removed when simplifying the wind tunnel model in the simulation. This conclusion will provide theoretical basis and data support for better virtual reproduction and numerical simulation of a wind tunnel.

Research of Aerodynamic Characteristics about Minibus

2011 ◽  
Vol 97-98 ◽  
pp. 752-755 ◽  
Author(s):  
Jing Yu Wang ◽  
Xing Jun Hu ◽  
Ying Chao Zhang ◽  
Bo Yang
Keyword(s):  
Numerical Simulation ◽  
Wind Tunnel ◽  
Flow Visualization ◽  
Theoretical Foundation ◽  
Aerodynamic Drag ◽  
Wind Tunnel Test ◽  
Aerodynamic Characteristics ◽  
Simplified Model

To research the aerodynamic characteristics of minibus, the simplified model is studied with simulation and wind tunnel test. The validated method was adopted in the numerical simulation, the wind tunnel test were carried out in order to validate the results of numerical simulation. The tests include aerodynamic drag measure, filament method, and laser flow visualization. Through the contrasted research the results of simulation and test, the aerodynamic characteristics of minibus was analyzed and the characteristic of field around minibus was discovered. The conclusions provide the theoretical foundation for styling optimization of minibus, which are very helpful to develop new vehicle styling.

Evaluation of Various Turbulence Models in Predicting Airflow and Turbulence around a Generic Vehicle Model

2014 ◽  
Vol 989-994 ◽  
pp. 3468-3472 ◽  
Author(s):  
Cheng Wu ◽  
Yi Ping Wang ◽  
Xue Yang
Keyword(s):  
Flow Field ◽  
Drag Coefficient ◽  
Turbulence Model ◽  
Aerodynamic Drag ◽  
Lift Coefficient ◽  
Turbulence Models ◽  
Separation Flow ◽  
Rans Turbulence Models ◽  
Aerodynamic Drag Coefficient ◽  
Selection Of

For vehicle external aerodynamic computation, the selection of the turbulence model is very important. In current research, ten RANS turbulence models were introduced to compute the time-averaged flow field around the Ahmed model with 25° backlight angle. In order to evaluate the feasibility of the turbulence model, the results were compared with the related published experimental data. The results showed that the two equations RANS turbulence models were more favorable to compute the vehicle external flow field, but parts of the two equations turbulence model just could predict the aerodynamic drag coefficient or lift coefficient effectively. However, the results further revealed that the realizable k-ε could obtain the more accurate drag coefficient and lift coefficient simultaneously, and simulate the complex separation flow in the wake.

Numerical Simulation and Impeller Optimization of a Centrifugal Pump

2012 ◽  
Vol 472-475 ◽  
pp. 2195-2198 ◽  
Author(s):  
Shao Ping Zhou ◽  
Pei Wen Lv ◽  
Xiao Xia Ding ◽  
Yong Sheng Su ◽  
De Quan Chen
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Flow Field ◽  
Centrifugal Pump ◽  
Turbulence Model ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Three Dimensional Flow ◽  
Field Simulation ◽  
Simulation Results

The three-dimensional flow field simulation of a centrifugal pump was presented by using commercial CFD code. In order to study the most suitable turbulence model, the three known turbulence models of Standard k-ε, RNG k-ε, Realizable k-ε were applied to simulate the flow field of the MJ125-100 centrifugal pump and predict the performance of the pump. The simulation results of head and efficiency were compared with available experimental data, and the comparison showed that the result of the numerical simulation by RNG k-ε model had the best agreement. Additionally, the effect of number of blades on the efficiency of pump was studied. The number of blades was changed from 4 to 7. The results showed that the impeller with 7 blades had the highest efficiency.

Numerical Simulation of Influence of Different Deflectors on Aerodynamic Characteristics of the Heavy Duty Truck

2013 ◽  
Vol 365-366 ◽  
pp. 474-477
Author(s):  
Yu Kun Liu ◽  
Qi Fei Li ◽  
Guan Qun Li ◽  
Ao Liu ◽  
Xing Jun Hu
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Drag Reduction ◽  
Aerodynamic Drag ◽  
Optimal Solution ◽  
Aerodynamic Characteristics ◽  
Heavy Duty ◽  
Heavy Duty Truck

In order to reduce the aerodynamic drag of heavy-duty truck, four different shape and style of deflectors based on the original one are added. With the method of numerical simulation, the influence of deflector on the flow field of the cab and the vehicle was analyzed, and the mechanism of aerodynamic drag and the measures of drag reduction were discussed in the study. When driving at speed of 30m/s, the aerodynamic drag will be significantly reduced with the contributions of all the four deflectors. The optimal solution can reach a reduction about 14%.

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