Design and evaluation of a pulsating flow wind tunnel

A wind tunnel was designed and built to produce a pulsating flow. The pulsation was achieved by a series of shutters (rotating with constant angular velocity) placed upstream of the settling chamber inlet. The system was optimized to obtain nearly sinusoidal velocity waveforms with the highest obtainable amplitudes over the frequency range of 3.4 to 31.3 Hz. The velocity and pressure waveforms are given for different shutters settings and conditions.

It was found that the velocity waveform shape and amplitude, obtained in the test section, are a strong function of pressure build-up in the diffuser upstream of the shutters box. An explanation is given, for various shutters settings and conditions, of how pressure release is achieved and how the pressure waveforms are generated.