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Technical Paper
Shui-chang Liu, Zheng-qi Gu, Li-fu Li, Yong Zhang, Wan-dong ZHAO
Abstract To shorten the development cycle and ensure the stability of the products, based on RNG k-e turbulence model and porous model, 3 dimension (3D) flow field Computational Fluid Dynamics (CFD) simulation is adopted to calculate the radiator group performance for a engineering vehicle being developed. Air-side flow field simulations of the radiator unit model are carried out firstly to obtain the radiators' air-side characteristics; then, the air flow and heat transfer in the whole air channel containing the radiator group are simulated simultaneously to get the inlet and outlet water temperatures of radiator group, at last, the real vehicle test is carried out to verify the simulation results.
Technical Paper
Wenguang Wu, Zhengqi Gu
Good handling stability becomes very important for heavily-laden electric wheel dump trucks that are operated on rough roads. To improve handling stability of mining dump trucks, nonlinear stiffness and nonlinear damping of the hydro-pneumatic suspension were considered as optimization variables. In this paper, based on the Daubechies wavelet's compactness and regularization and least-square method, the nonlinear stiffness and damping are identified. In order to verify the results of the parameter identification, the multi-body system dynamic model of the truck was built in ADAMS/view. By comparing the simulated results and tested ones, we find acceleration-history and power spectral density of acceleration are very close. And then, based on the approximate model method, the optimization model was built in ISIGHT. The nitrogen column and the orifice diameter were defined as the design variables. Finally, the handling stability was optimized by applying the genetic algorithms method.
Technical Paper
Zhengqi Gu, Xin Song, Yejie Jiang, Xu Gong
Realizable k-ε turbulence model has been used widely for engineering development. In this turbulence model, the default values of empirical coefficients such as C₂, σk and σε are obtained from some particular experiments. They are a good choice for most simulations-though may be not the best choice for simulating the aerodynamic characteristics of road vehicle. In order to improve the accuracy of simulation, a set of new empirical coefficients should be designed especially for simulating the aerodynamic characteristics of road vehicle. These empirical coefficients are found out by DoE (design of experiments) in this paper. Firstly the value range of empirical coefficients is decided by the laws that the aerodynamic force coefficients change with altering of empirical coefficients. Secondly 20 sets of empirical coefficients are obtained randomly by applying optimal Latin Hypercube method in Isight.
Journal Article
Jun Chen, Zhengqi Gu, Yiping Wang
Numerical simulations are performed to investigate noise generated by flow in automotive HVAC ducts. A hybrid computational method for analyzing flow noise is applied: Large Eddy Simulation (LES) for predicting flow fields and Multi-domain boundary element method for predicting acoustic propagation. LES gives time-resolved solutions of flow velocity and pressure fields. By applying the acoustic analogy theory, the unsteady flow parameters are translated into sound source in evaluating the acoustic propagation. The computational result shows the noise caused by the HVAC ducts is strong. The noise is of broadband with a peak value at 370Hz. A major contribution of the noise generation is from the center ducts. Two design modifications of the center ducts are explored to regulate the flow structures with the ducts for reducing noise generation. Test results demonstrate the effectiveness of the modifications.
Technical Paper
Xu Gong, Zhengqi Gu, Zhenlei Li, Xin Song, Yiping Wang
Due to the energy crisis, one of the important challenges in the Auto industry is to reduce the fuel consumption of the vehicle. And the higher speed is, the more fuel consumption is taken by the aerodynamic drag. Mostly, the aerodynamic drag lies on the shape of the vehicle. Consequently, the improvement of the aerodynamics of vehicle shape, more precisely the reduction of their aerodynamic drag, becomes one of the main topics of the automotive researchers. For a container-truck, the three dimensions of the container are standard and unchanged, and the shape of cab is almost fixed by the aesthetic sculpt. For those container-trucks, aerodynamic additional equipments can decrease the aerodynamic drag evidently, especially the wind deflector. Accordingly, this paper describes a method which combines CAD, CFD, Approximate model and optimization carried out on the aerodynamic shape of a container-truck's wind deflector.
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