ABSTRACT

significant harmonic is found to be the twelfth harmonic, that is the interesting frequency range is from 175Hz to 2100Hz. Hence, it is found that both the firstorder square-root and Brown's approximations can be used in the measurement of fluidborne noise characteristics, but the former is prefered due to its simple form. The following analyses all are based on the first-order square-root approximation. In addition, it should be noted from Fig.3 that at high frequencies (over 1750Hz) the exact model is oscillating. This oscilation is expected to result from the calculating error of the exact model by using the finite sum series forms of the Bessel functions.