AVRG: A PDP 8/I Data Acquisition and Averaging Program for Synchronous Hot Wire Measurements.

摘要

The program,in function-modified FOCAL,is specifically designed to enable measurements to be performed on oscillating vertical velocity profiles in the mouth of a flow-excited cavity resonator. Simultaneous hot wire and pressure microphone data samples are recorded at an exact multiple (20X) of the oscillation frequency so as to obtain a synchronous record of the cyclic variation of longitudinal stream velocity at many points in the mouth region. Data is atuomatically averaged over 100-cycle intervals to remove turbulent background variation. From the stored data,either two or three dimensional velocity profile information can be reconstructed,using sound pressure at the base of the cavity as a phase reference. Options are provided for Fourier analysis,real time (oscilloscope) display,and TTY printout. (Author)