Dynamic Response of Fluid Lines

Abstract

The use of hydraulic transmission lines in automatic control, liquid-propellant rocket, and other systems requires accurate knowledge of their dynamic response. In this paper the effects of fluid viscosity and compressibility are included to derive transfer functions relating the pressure and velocity variables at the two cross sections of a line. The results of theoretical analysis are compared with experimental data obtained from frequency-response tests. The analysis includes the significant effect on the dynamic response caused by the natural frequency of vibration of the line in the longitudinal direction. It is shown that in small-diameter lines the viscous effects cannot be neglected. The theoretical analysis may be used to improve the performance of systems incorporating hydraulic networks.

Acoustic Resonance in a Reservoir-Pipeline-Orifice System

“…The frequency-controlled oscillating piston can excite the system directly [5][6] or indirectly (oscillating liquid column) [7][8][9]. Typical frequency-controlled valve designs among others include a servo-valve unit [10], a sirentype valve [11] and a unit with variable periphery disc [12]. In the Hydralab III project [1] a Svingen-type rotating disc [13] has been used, which is described by the orifice equation below.…”

Nonlinear Pressure Wave Analysis by Concentrated Mass Model (1st Report, Suggestion and Validity Verification of Analytic Model)

“…We develop the expression of the velocity ( ) u r and the cross-sectional average velocity u by using a method similar to that by D'Souza (8) . First, we assume 0 ( ) .…”

“…The characteristic of connecting nonlinear springs is derived from the adiabatic change of fluid, and the connecting damper is derived from the normal stress of a fluid. Based on research by D'Souza (8) , the equivalent mass and equivalent damping coefficient of the base support damper are derived from the viscosity of fluid and velocity distribution. Then, pressure waves generated in a hydraulic oil tube (9) , in a sound tube (5) and in a plane-wave tube (7) are analyzed numerically by the proposed model to confirm the validity of the model.…”

A water hammer analysis of pressure and flow in the voice production system

“…The choice of the version is problem-dependent: basic water hammer neglects friction and damping mechanisms, classic water hammer takes into account fluid wall friction, extended water hammer allows for pipe motion and dynamic FSI [19][20][21]. The method of characteristics (MOC) is the standard numerical method for solving the water hammer equations [22].…”