Analysis of the Frequency Response of a Fluid Amplifier Using Unsteady Flow Characteristics

This paper is mainly concerned with the theoretical and experimental study of the frequency response of an analog fluid amplifier. The channels are considered as distributed parameter systems and the frequency effects on the charcteristics of nozzles, vents, and jet interaction are taken into account. The paper considers the dynamic behavior of the flow in vortex vents and the interaction of two jets : a discontinuous profile is used to approximately describe the average velocity distribution in the jet in order that a recursive solution for the eigenvalues resulting from a small perturbation be obtained. The amplifier was tested by means of an electropneumatic signal generator at frequencies up to 3000 Hz. A comparison with experiments performed in the potential core region shows that the linear theory correctly predicts the passband of the jet which is constant provided a local Strouhal number is used.