Research On The Sounding Mechanism Of Multi-inlet Hydrodynamic Whistle Whistle

The fluid-powered sound generator has been widely used in many fields due to its advantages of convenient processing and simple operation.The vortex whistle is a kind of typical fluid-powered sound generator.However,so far,the research on vortex whistles is mainly concentrated in the air,and the broadband radiation model is generally used to analyze the sound radiation characteristics of the vortex whistle,and there is little research on the frequency and sound field related information.Secondly,there are few studies on the sound mechanism of vortex whistle,which limits its application due to its low efficiency.Considering the rotating structure of the vortex whistle,the total velocity of the fluid has three-dimensional vector property,and the tangential velocity can improve the flow field of the vortex whistle,thus increasing the sound radiation of the whistle.Therefore,this paper considers structural optimization from the angle of inlet location and inlet quantity.compares and analyzes the acoustic radiation characteristics of different structural whistle,and then studies the sound generation mechanism.In this paper,based on the related theories of fluid dynamics and aeroacoustics,and with the help of relevant theories of computational fluid mechanics,the FLUENT module in the Workbench platform in the ANSYS software package is used to simulate the hydraulic whistle,based on the combination of large eddy simulation and acoustic analogy.The main research work is as follows:1.Three aspects of simulation for single entrance vortex whistle,First of all,to explore the influence of entrance position on the whistle radiation of the hydraulic whistle,combining the results of the contours of sound power level and sound spectrum(energy)map,it obtained that when the entrance is located in the middle of the cavity,the vortex whistle has the best sound radiation.Secondly,taking the sentinel in the middle of the entrance as the simulation model,the acoustic model of the hydraulic vortex sentinel is explored.It is found that the contribution of the quadrupole to the total sound radiation of vortex whistle is negligible,the source of the dipole sound plays a major role,and the total radiated sound energy of the vortex whistle is replaced by the sound of the dipole.Finally,the effect of inlet pressure on the sound radiation of a single entry whistle was investigated,and it was found that the sound radiation energy of a single entry whistle increased with the increase of the inlet pressure.2.Two types of multi-entry vortex whistle are designed by increasing the number of inlets,equal pressure and equal flow whistle and equal pressure and non-equal flow whistle.In the case of neglecting the resistance,the equal pressure non-equal flow(compared to the single inlet,the total pressure of the inlet pipe is equal,the total flow changes,the same below)and the equal pressure and equal flow whistle(compared to the single inlet,the total pressure and the total flow are equal to the single inlet,the same below).The research work is mainly carried out from the following three aspects.First,by comparing and analyzing performance of isobaric non-equal flow whistle and traditional single-entry whistle,it is found that the acoustic radiation energy of isobaric non-equal flow multiple entry whistle increases with the number of inlets.Four entrances are higher than three entrances,Secondly,by comparing and analyzing the acoustic characteristics of isobaric equal flow whistle and traditional single-entry whistle,the results show that in the acoustic radiation and equal-flow whistle,The acoustic radiation energy of three entrance is lower than that of single entrance.Double and four entrance have higher acoustic radiation energy than sing entrance.The primary peak frequency is that the number of entries is even higher than the number of entries is odd.Finally,by comparing and analyzing the causes of the different between the two types of whistle radiation,it is found that for isobaric non-equal flow whistle,the axial velocity and the sound radiation changed with the increase of inlet with the same rule.The total velocity and tangential velocity and the frequency of the main peak increase with the entrance,and the change law is the same.For equal pressure flow whistle,the axial velocity and radial velocity contribute greatly to the energy of acoustic radiation.Comprehensive material saving,processing and energy consumption considerations,The double entry whistle in equal pressure and non-pressure flow is applicable.Finally,the pressure of the selected optimal structure whistle was changed,and it was found that the acoustic radiation increased with the increase of the inlet pressure.