Assessment of the Moving Point Method for Numerical Calculation of Fluid-Structure Interaction in Water Hammer

摘要

The problem of providing an accurate numerical method for modelling fluid-structure interaction in practical water hammer calculations for power station pipe networks is addressed. The application of the moving point method to a problem representative of practical water hammer is presented. A suitable model including both liquid pressure waves and pipe wall tension waves if formulated as a set of partial differential equations with algebraic equations and boundary and initial conditions. The problem is non-dimensionalized, to identify key parameters, and a suitable linearized problem is constructed by omitting small terms. The problem is transformed to characteristic variables which are shown to be simply transported along the pipe without change of value. This motivates the choice of the moving point method. In the course of the work a program WHOMP (Water Hammer On Moving Points) was developed which exploits the moving point method. It is specific to the problem of a single pipe with thin elastic walls but the boundary and initial conditions permitted are sufficiently general that any reasonable physical problem for a single pipe can be addressed. Results of WHOMP for the model problem are compared with experimental and other numerical results including superficially those from a commercially available code FLUSTRIN. Some consideration of extending the moving point method to practical pipe networks is given. This includes the incorporation of bending and torsion waves in the pipe wall and incorporation of additional physics leading to significant non-linearity. (ERA citation 14:002975)