Simulation of Cavitation and Pressure Surge: An Engineering Approach

Abstract

The prediction of the magnitude of the pressure surge in aircraft fuel systems is important from the standpoint of designing systems that will not exceed the maximum surge pressure allowed and also to determine the limit pressure so that lightweight systems can be designed. Because aircraft refueling systems are relatively low pressure, the formation of gaseous products, cavitation, introduces severe nonlinearity not only in the form of dampened pressures but also in decreased propagation speed. The linear relation between the bulk modulus, pressure, and density that exists in high-pressure systems is made nonlinear by the formation of gases. This paper describes a simulation method for predicting the pressure surge in aircraft fuel systems that is suitable for engineering purposes. A model for gas formation has been developed. The dynamic simulation is a relatively fine, one-dimensional, discrete distribution of the fluid solved with MacCormack’s predictor corrector technique. Simulation results are compared to actual fuel rig tests. There is a step-by-step description of how the simulation model was tuned to correlate with the measured data. After this, some practical uses of the model, actual simulations used for fuel system design, are presented.