Whistles: From toys to industrial devices and applications

The Hatmann whistle, a high efficiency acoustic device with various sounding advantages, differs from other tone generators due to its high acoustic output capability and working principles. The advantages of the whistle include purely aeroacoustic sound generation, high sound quality due to intense tonal content and high amplitude, and tunable frequency of sound using the geometrical parameters. The tone frequency of the whistle corresponds to the quarter-wavelength mode applicable for tubes closed at one end and open at the other. Non-isentropic flow in the tube causes the heating mechanism and the heating effect is more pronounced when the resonance generates high amplitude pressure oscillations. The geometrical resonance of the tubes in Hartmann whistle include factors such as enhancement of acoustic efficiency, thermal effects, and adaptation to practical situations.