The Experimental Study Of Composite Whistle Learning Characteristics

Hydrodynamic sound generator, which is characteristic of simple structure, easy to use, low cost, high processing capacity, durability, and other significant advantages, has been widely used in the homogenization, grinding, atomizing, dust elimination, combustion-supporting, as well as in promoting chemical reactions and other areas. The common type of hydrodynamic sound generator is Hartmann whistle, vortex whistle and reed whistle.Hydrodynamic sound whistle becomes a hot subject for worldwide acoustics workers to study recently. Especially the pneumatic acoustics need higher sound pressure level and wider-band sound, while the hydrodynamic sound whistle is the most appropriate sound generator. However, there is no major breakthrough in study of Hartmann whistle, due to its complexity in the sound generator principles, and there has been no a sound principles to make a perfect explanation so far. Most domestic and overseas studies only analyze and summarize the conclusions of experimental or use numerical simulation and experience to change the shape and size of the whistle to optimize the flow field and get a better sound effect. Convenient processed and the structure is stable with no moving parts, vortex whistle is a very promising fluid whistle. In the industry, vortex whistle has been applied to atomize fuel and cool water. But because the application of vortex whistle is not very extensive currently, have not caused the serious attention of domestic and foreign researchers, and the study on the principle of sound is very little, so far, its vocal efficiency is very low still. The compound whistle which is composed of vortex whistle and Hartmann whistle, is a new proposed hydrodynamic acoustic generators in recent years, the research about it is even more rarely. But due to existence of vortex whistle can stabilize the audible signal, thus the sounding zone length of the compound whistle is longer than Hartmann whistle. That is the adjustable range of compound whistle is longer, and compound whistle is more conducive to the operation and application. So the further research about the characteristics of compound whistle is very important.The thesis carried out a study about the acoustic characteristics of the small-size vortex whistle and compound whistle which is composed by the small-size vortex whistle and Hartmann whistle through experiments. And concluded the experimental results through arranged and analyzed the experimental data. Comparing the acoustic characteristics of vortex whistle with compound whistle and Hartmann whistle with compound whistle respectively, and reached their respective advantages and disadvantages, in order to provide theoretical reference of further optimize the structure and size of sound whistle.In summary, this paper is focused on the following aspects:1. The application of the Hartmann whistle and the research progress of Hartmann whistle, vortex whistle and compound whistle are summarized and introduced.2. According to the original theoretical basis, the size of Hartmann whistle and vortex whistle were designed, and combined into compound whistle.3. The effects of the main parameters on the acoustic characteristics of vortex whistle were studied.4. The acoustic characteristics of the best location of the first sound area and the best location of the second sound area of compound whistle are studied respectively.5. The acoustic characteristics of vortex whistle and compound whistle were compared and analyzed.6. The acoustic characteristics of Hartmann whistle and compound whistle were compared and analyzed.