Study On Vibration Energy Harvesting Of Vortex Street From Suspension Damper At High Reynolds Numbers

In this paper,the vehicle suspension was taken as the research object for the micro power supply problem of vehicle control system.Firstly,a new scheme to recover the vibration energy of the rear flow field of the shock absorber in running was proposed.Secondly,the morphological characteristics of the vortex were analyzed.Finally,the piezoelectric energy harvester was designed.The main research contents were as follows:(1)The road model and the suspension dynamics model were established.Combined with the working road conditions and driving speed of the vehicle studied,the motion state of the vehicle and the suspension was simulated and analyzed.The motion output responses of vehicle acceleration,suspension dynamic deflection and tire dynamic load were obtained by simulation,and the compression of shock absorber spring was determined.(2)According to the compression state of the spring,a simplified 3D model of the step cylinder of the shock absorber was established,and the simulation calculation was carried out for the characteristics of the vortex around the step cylinder under different speed and Reynolds number.The results show that the size,shape and rising Angle of the wake vortex were affected by the diameter of the cylinder,Reynolds number and boundary conditions.The direct effect of "downwash" on the distribution and development of vortices was verified at the variable cross section.The distribution angle of vortex pressure was determined,which provided theoretical support for piezoelectric energy recovery of vortex-induced vibration The vortices around a step cylinder were rezoned under three kinds of bounded high Reynolds number flow fields,and two new types of vortex connections were observed.(3)According to the piezoelectric constitutive equation and the coupling equation of the system,the piezoelectric energy harvesting two-way fluid-structure coupling model of vortex-induced vibration was established.The energy harvesting simulation was carried out in three aspects: velocity,position of piezoelectric patches and size of the piezoelectric patches.The results show that the best installation location was related to wind speed and cylinder diameter.The best location for piezoelectric energy recovery after the small cylinder was D behind the central axis.The best position behind the big cylinder was at 2D(at medium and high speed)and 4D(at low speed).The 120 mm long piezoelectric patches was more suitable for the trailing vortex piezoelectric energy regenerator,and the maximum average peak voltage was 2.41 V.(4)A 1:1 test bench was built to collect the piezoelectric voltage around the vortex.The experimental results were basically consistent with the simulation data,which verified the correctness of the modeling and simulation.Through the research in this paper,the fluid induced vibration and piezoelectric energy harvesting were applied to the vehicle suspension system,and the optimized new structure scheme could effectively recover the energy of vortex vibration.The initial escape height difference(Δh)was used to verify the effect of "downwash" movement on the growth and evolution of edge vortexes in N region.The observed two new vortex connection modes,the opposite side half ring connection and the same side double half ring connection,provide a theoretical basis for vortex shape control and the design of suspension energy harvesting device.The structure scheme,flow field analysis and test results showed that the method of piezoelectric energy harvesting by vortex-induced vibration was an effective way to design the on-board micro power supply.