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RISS 인기검색어
- 검색키워드
- 저자 : Xingjun Hu (검색결과 4 건)
- 무료
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- 유료
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DRAG REDUCTION PREDICTION OF AHMED MODEL WITH TRAVELING WAVE BASED ON BP NEURAL NETWORK
Hu Xingjun Hu,Jinglong Zhang,Yufei Luo,Jingyu Wang,Pengzhan Ma,Wei Lan,Chunbo Dong 한국자동차공학회 2022 International journal of automotive technology Vol.23 No.5
In this paper, a traveling wave model is proposed to explore its influence on the aerodynamic drag of a Ahmed model, the experimental and numerical results of aerodynamic drag coefficient CD for the Ahmed model are in good agreement. Then by defining the aerodynamic benefit coefficient ΔCD as the evaluation index for the orthogonal experiment, range analysis is conducted to determine the influences of the amplitude A, wavelength λ and frequency ω of the wave and the vehicle speed u on ΔCD. After the analysis it can been found that λ has the least importance among these parameters, hence A, ω and u are used to construct the 105 samples for training the BP neural network to predict ΔCD, results show that ΔCD obtained from the neural network is significantly affected by the parameters of traveling wave. The prediction accuracy of the network is furtherly verified by another 15 samples which are also built on A, ω and u, and the corresponding data overlap rate of ΔCD is 96 %, so it can be concluded that the BP neural network constructed in this paper is accurate enough to predict ΔCD.
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Aerodynamic drag reduction based on static traveling wave structure
Xingjun Hu,Zewei Wang,Jiuchao Li,Guo Yu,Jingyu Wang,Wei Lan,Jinglong Zhang,Pengzhan Ma 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.5
To explore the influence of the traveling wave parameters on the aerodynamic characteristics of Ahmed models, the geometric model of the traveling wave wall is used as the study object, and the influence of the traveling wave geometric parameters on aerodynamic drag is studied by numerical simulation. A cosine-type traveling wave digital model is established on the basis of Ahmed’s original model. Results show that the static traveling wave structure can play a good role in reducing drag under some driving conditions. The traveling wave’s drag reduction characteristics are affected by the layout position, depth, wavelength, and other related parameters and more affected by driving speed. Finally, a group of working conditions with good drag reduction effects is selected, and the principle of drag reduction by using static traveling wave structure is explained qualitatively and quantitatively through velocity field, shear stress, and pressure field.
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Heat transfer enhancement in cold plate based on FVM method and field synergy theory
Xingjun Hu,Yu Liu,Wei Yan,Jinglong Zhang,Jingyu Wang,Wei Lan,Tao Sang,Tianming Yu 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.5
To optimize the overall heat dissipation performance of the straight channel of a cold plate for lithium battery in vehicles, we used the wavy channel to optimize the structure and uses the face-centered central composite design (FCCCD), which takes the overall thermal-hydraulic performance factor as the response to explore the interaction mechanism of the flow field and temperature field in wavy channel of the cold plate. When the amplitude of the wavy channel is 1 mm and the number of cycles is 4, the overall thermal-hydraulic performance will reach its maximum with an increase of 17.4 % relative to the straight channel. Then, for the coolant, we explored the heat transfer performance of the nanofluid. The heat transfer coefficient of the nanofluid with a volume fraction of 2 % is 117 % higher than that of pure water and does not cause a significant increase in pressure drop.
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Flow control of automobile with plasma vortex generator
Xingjun Hu,Jinglong Zhang,Zheng Hui,Yufei Luo,Peng Guo,Jingyu Wang 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.6
In this study, a plasma actuator was used to examine the wake flow control of an automobile with the aid of wind tunnel test methods, such as surface pressure measurement and particle image velocimetry (PIV) measurement. The control mechanism and law of the plasma vortex generator in the wake field of an Ahmed model were described. The effects of certain factors were analyzed. Results showed that the streamwise vortex induced by a dielectric-barrier-discharge vortex generator (DBD-VG) could promote the mixing of high-speed airflow above the slanted surface at the end of the model and low-speed airflow near the wall by increasing airflow turbulence, thereby inhibiting the generation of separation bubbles and reducing drag. Drag reduction decreased as the total discharge length of the DBD-VG decreased, but its backward distance had the largest effect on the drag reduction rate, followed by its counter distance. Meanwhile, the shortening of the streamwise length had the least effect on the drag reduction rate. When installing the DBG-VG, the end of the actuator should be arranged near the separation line to enable the generation and development of the streamwise vortex before the separation line to achieve the strongest flow control effect. The DBD-VG need not be arranged precisely at the airflow separation point, which demonstrates its favorable versatility. At low speeds, a maximum drag reduction rate of -8.51 % was obtained at an excitation voltage of 13 kV under the control of the DBD-VG, which demonstrated its strong flow control capability.
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