Stig Ingamansson’s Noise Control: Principles and Practice

C1:  SOUND PRODUCTION IN AIR OR GASES – WIND TONES 

Wind Tones can be Eliminated 

When air passes by an object at certain speeds, a strong pure tone, known as a Karman tone, can be produced. This tone can be prevented by making the object longer in the direction of flow, such as with a “tail,” or by making the object’s shape irregular. 

Principle 

Application with Wind Currents 

C2:  SOUND PRODUCTION IN AIR OR GASES – WIND TONES 

Air Flow Past Hollow Openings Should be Avoided 

When air or another gas is blown at certain speeds across the edges of an opening to a cavity, loud pure tones are generated. This is how wind instruments operate. The greater the volume of the cavity and the smaller the opening, the lower the frequency will be. 

Principle 

Application with Air and Steam Jets/Objects in Rapid Motion