Numerical Simulation And Experimental Study On Sound Characteristics Of Whirlpool

This thesis studies on the Hydrodynamic sound generator which is vortex whistle. Because its structure is simple and it has no moving parts, which is more convenient to operate and durable. Its power source not only can be gas but also liquid. It has already been applied to the atomized fuel, cool water and some other industries. Therefore, its application prospect is very extensive. But currently, because the study of vortex whistle is not very extensive and deep, and can not greatly cause the researchers’ attention. The study on the principle of sound is very limited, so the sound radiation efficiency is still not too high. But some studies have shown that the structure of vortex whistle and fluid in the vortex whistle can affect audio frequency and efficiency significantly, so it is necessary to further study that the geometric structure of vortex whistle and fluid parameters influence on the sound radiation characteristics.This article firstly introduces the research and application of vortex whistle, and then introduces some basic knowledge about the fluid dynamics and aero acoustics associated with vortex whistle. We design four groups of different sizes vortex whistle. In the first group, it changes the diameter of the outlet pipes. In the second group, it changes the length of the outlet pipes. In the third group, it changes the diameter of the cavities. In the fourth group, it changes the height of the cavities. Firstly above vortex whistles are simulated. We can obtain the distributions of velocity, pressure, turbulence intensity, turbulence kinetic energy, sound power density and sound power density level on the axis of vortex whistle. And then give some explanation after summarizing and analysis. Then design the experiment and research it. The relationship between the sound frequency and sound pressure level of the vortex whistle and the structure parameters of the vortex whistle is measured and analyzed, and the result of the experiment is summarized. Finally the results of simulation and experiment are combined and analyzed. The characteristics of flow field distribution and the acoustic radiation characteristics of Spiral whistle with different sizes are summarized.The research results showed that the diameter of outlet pipe is the main factor that greatly influences the distribution of flow field about vortex whistle. The axial velocity and tangential velocity on the axis are almost not affected by the structure parameters change. The turbulence intensity, turbulence kinetic energy, sound power density and sound power density level inside the cavity is the biggest and the main source of sound field. The sound radiation frequency and sound pressure level are affected by the gas pressure of inlet. The distribution of flow field and sound radiation efficiency are affected by the ratio of the diameter of outlet pipe and the cavity directly. The outlet pipe length should not be too long. Otherwise, it will increase the flow resistance and the energy loss of the fluid, thus decrease the fluid velocity and the sound radiation efficiency. The height of the cavity affects vortex whistle a little. It should not be too high or too low, and maintained at15mm as the best.In a word, in this article the experimental conditions for air driven vortex whistle, its sound frequency and sound radiation intensity depend on many factors. The effects of cavity height can be ignored. The higher the inlet pressure, the higher the frequency and the sound pressure level. Cavity diameter, outlet pipe length and diameter influence the frequency and sound pressure level differently. Need to consider comprehensively the actual needs to determine its size.Above, study methods and study conclusion for the study of sound production mechanism and the structure optimal design of the vortex whistle provides a certain theoretical basis and design basis.