The influence of geometric parameters on the transfer function of a pressure tube with special consideration of nonlinearities

The influence of various parameters such as tube length, change of diameter, tube shape, and tube material on the transfer function was investigated experimentally. In many cases there is a pronouncedly nonlinear behavior. A method is presented to estimate the transfer characteristics for such a nonlinear system. When unsteady pressures are measured on the end of a pressure tube instead of directly at the desired site, the pressure tube changes the unsteady signal. This characteristic is demonstrated to be frequency dependent. Pressure amplitude measurement results are used to determine real values for the transfer function. An empirical model of an estimated pressure control system is given. The possibility of approximating nonlinear pressure transfer from unsteady pressure measurement is shown.