Numerical computation and optimization design of pantograph aerodynamic noise

Firstly, the aerodynamic resistance and lift of the pantograph are computed in this paper, which is compared with the experimental results. As shown from the result, the above proposed simulation method is very reliable. Secondly, the velocity field and vorticity distribution of the pantograph are computed under the effect of the fluid. It is presented from the result that the values of the pantograph head, push rod and base are relatively large, mainly because rather prominent structures and more parts in these areas have some interference on the flow field. Next, the sound source intensity and sound field distribution are computed based on the aerodynamic characteristics. There are the relatively large values in the pantograph head, push rod and base, which is consistent with the aerodynamic characteristics results of the pantograph. In addition, the sound source intensity and sound field of the pantographs are decreased gradually along with the increasing frequency. Finally, cylindrical rod in the pantograph head and push rod which affect the sound field quite largely are applied a layer of porous sound absorption material. In addition, base surface is also applied this material. Then, the corresponding sound source intensity and sound field are computed and compared with the original values. It is shown from the computational result that the pantograph aerodynamic noise can be effectively improved by applying a layer of porous sound absorption material

Full-spectrum noise prediction of the high-speed train head under multi-physics coupling excitations based on statistical energy analysis

The force between wheels and rails of the high-speed train was firstly extracted and applied into the computational model of radiation noises of wheels and rail respectively. As a result, the radiation noise of wheels and rails was obtained. As can be seen from the result, radiation noises of wheels had an obvious directivity on the body surface, while radiation noises of rails had an obvious periodicity on the body surface. With the increase of the analyzed frequency, both directivity and periodicity were shown more obviously. Then the aerodynamic model of the high-speed train was established, and the pressure and velocity distributions on the train surface were computed. The maximum pressure was at the tip of the nose of the high-speed train, the maximum velocity was at the transition of the cabin, and more serious eddy was in the rear of the high speed train. Based on the computed pressure distribution, the aerodynamic noise was distributed evenly on the entire body surface, which was gradually increased with the increasing analyzed frequency. Finally, the wheel radiation noise, rail radiation noise and aerodynamic noise were extracted as excitations and applied into the SEA (Statistical Energy Analysis) model of the high-speed train, in order to compute its full-spectrum noise under multi-physics coupling excitations. The computational result was compared with the experimental result. It was presented that the difference of average sound pressure level (SPL) was 2.8 dB between the experimental and numerical simulations within the entire analytical frequency band. The SEA model with considering the multi-physics coupling was effective

Numerical computation and optimization design of pantograph aerodynamic noise

Firstly, the aerodynamic resistance and lift of the pantograph are computed in this paper, which is compared with the experimental results. As shown from the result, the above proposed simulation method is very reliable. Secondly, the velocity field and vorticity distribution of the pantograph are computed under the effect of the fluid. It is presented from the result that the values of the pantograph head, push rod and base are relatively large, mainly because rather prominent structures and more parts in these areas have some interference on the flow field. Next, the sound source intensity and sound field distribution are computed based on the aerodynamic characteristics. There are the relatively large values in the pantograph head, push rod and base, which is consistent with the aerodynamic characteristics results of the pantograph. In addition, the sound source intensity and sound field of the pantographs are decreased gradually along with the increasing frequency. Finally, cylindrical rod in the pantograph head and push rod which affect the sound field quite largely are applied a layer of porous sound absorption material. In addition, base surface is also applied this material. Then, the corresponding sound source intensity and sound field are computed and compared with the original values. It is shown from the computational result that the pantograph aerodynamic noise can be effectively improved by applying a layer of porous sound absorption material

Multi-objective optimization for dynamic response of the car frame system

Modern high-speed structures often have great vibration, noise and dynamic loads. Traditional technology pays more attention to geometric constraint, strength constraint, stability constraint and frequency constraint generally. During the running process of a car, road roughness will cause vibration of the car. When the vibration reaches certain extent, it will not only affect the fatigue life of the car, but also affect the seat comfort and operation stability. In this paper, the optimal solution considering the dynamic response of the car under the dynamic excitation of the road was sought by taking acceleration response as the constraint, the minimum mass and the minimum acceleration response as the optimization objectives. Because the car model is complicated, a hybrid finite element model was built by simplifying the car model to obtain frame, Frequency response analysis was carried out on the car frame to extract mass and acceleration response. Optimization analysis was also carried out on the car frame by means of linear weighted sum method and NCGA method. The results show that both of them can optimize the mass and acceleration of the car frame and can meet the strength requirements

Numerical computation and optimization design of pantograph aerodynamic noise

Firstly, the aerodynamic resistance and lift of the pantograph are computed in this paper, which is compared with the experimental results. As shown from the result, the above proposed simulation method is very reliable. Secondly, the velocity field and vorticity distribution of the pantograph are computed under the effect of the fluid. It is presented from the result that the values of the pantograph head, push rod and base are relatively large, mainly because rather prominent structures and more parts in these areas have some interference on the flow field. Next, the sound source intensity and sound field distribution are computed based on the aerodynamic characteristics. There are the relatively large values in the pantograph head, push rod and base, which is consistent with the aerodynamic characteristics results of the pantograph. In addition, the sound source intensity and sound field of the pantographs are decreased gradually along with the increasing frequency. Finally, cylindrical rod in the pantograph head and push rod which affect the sound field quite largely are applied a layer of porous sound absorption material. In addition, base surface is also applied this material. Then, the corresponding sound source intensity and sound field are computed and compared with the original values. It is shown from the computational result that the pantograph aerodynamic noise can be effectively improved by applying a layer of porous sound absorption material