Numerical Research On The Mechanism Of Turbulent Flow Induced Noise Of High-speed Train Bogies And Coating Noise Reduction

Although high-speed railways of China started late,the speed of development,the scale of construction and the strength of transport capacity all of these occupy the first place in the world.By the end of 2022,the mileage of high-speed railways operating in China reached42,000 km,ranking first in the world.The aerodynamic noise of high-speed trains is proportional to the sixth power of its operating speed,and with the speed increase of high-speed trains,the aerodynamic noise becomes a problem that cannot be ignored.Based on the computational fluid dynamics software STAR-CCM+,a combination of numerical simulation and FW-H integration method is used to verify the feasibility of the aerodynamic noise problem by comparing the tandem double-cylinder aerodynamic noise arithmetic with experimental data.Aiming at the flow-induced noise problem in the bogie area of a certain type of high-speed train,the flow field characteristics,dipole sound source characteristics and far-field noise characteristics of the bogie area under different speeds were explored.In addition,two types of coating aerodynamic noise reduction models,semi-coating bogie and full-coating bogie,are constructed for the coating range of the skirt structure in the bogie area to investigate their noise reduction effects.The results show that during the operation of high-speed trains,the velocity of the fluid in the bogie cabin is significantly lower than that outside the bogie cabin,and the wheels,traction motors and other parts directly impacted by the incoming flow have flow separation points,and the fluid flow velocity near the flow separation point is significantly higher than that of other parts,and the parts with higher flow velocity are usually also parts with high intensity vortex,high turbulent kinetic energy and large amplitude of surface pulsation pressure.The large sound power radiated by the dipole sound source on the surface of the bogie parts occurs near the wheels,traction motors and other parts that are directly impacted by the incoming flow and the surface flow separation points.The parts whose surfaces radiate the most sound power are wheels.The study also revealed the directivity and attenuation characteristics of flow-induced noise in the bogie area.The flow-induced noise in the bogie area has obvious directivity characteristics,and the A-weighted sound pressure level maximum value appears at the three noise monitoring points of 0°,90° and 180°.The lateral attenuation characteristic curve of bogie flow-induced noise shows the characteristics of logarithmic function,and the attenuation amplitude decreases with the increase of distance from the bogie.The attenuation characteristic curve of bogie flow-induced noise flow showed a trend of attenuation from the center of the bogie to the upstream and downstream.The closer to the center of the bogies,the greater the attenuation amplitude,and the upstream attenuation rate was faster than that of the downstream.The attenuation amplitude of the bogie flow-induced noise vertical attenuation characteristic curve below 0.65 m is small,and the part above 0.65 m shows a linear attenuation trend similar to the primary function.The study of the coating range of skirt structure in the bogie area shows that the calculation model of the semi-enveloping bogie and the calculation model of the fully enveloping bogie have weakened effects on the velocity,vortex,turbulent kinetic energy and pulsating pressure of the bogie surface flow field in the bogie area,which can effectively reduce the maximum sound power radiated on the surface of the pillow beam and air spring.The directivity characteristics,lateral attenuation characteristics,flow attenuation characteristics and vertical attenuation characteristic curve distribution of noise information received by the two clad noise reduction aerodynamic models at the far-field noise monitoring point were lower than those of the calculation model without enveloping bogie,and the overall noise reduction effect of the fully enveloping bogie calculation model was more obvious,which had certain positive significance for further reducing bogie noise.