Fluid Transmission Line Dynamics for Signals of Finite Amplitude.

摘要

The transient response of a straight, cylindrical, fluid transmission line to a finite-amplitude pressure input is studied numerically to identify deviations from linear behavior. A nonlinear, finite-difference method is developed to predict the changes in the shape of a pressure wave as it propagates. The finite-difference algorithm is also applied to a linearized version of the governing equations to generate a basis against which to identify nonlinear behavior. The finite-difference method accounts for viscous losses and heat transfer. An algebraic model for calculating eddy-viscosity in transient, turbulent flows is included. Numerical simulations of a semi-infinite transmission line are performed using trapezoidal and half-sinusoidal pulses as well as a terminated-ramp as input pressure signal waveforms. Significant differences between linear and nonlinear results are found, even for input signals with maximum pressures less than two percent of the initial, undisturbed pressure. Theses. (RRH)