Numerical simulation of dynamic wave rotor performance

A numerical model has been developed that can simulate the dynamic (and steady-state) performance of a wave rotor, given the geometry and time-dependent boundary conditions. The one-dimensional, perfect-gas, computational fluid dynamics-based code tracks the gasdynamics in each of the wave rotor passages as they rotate past the various ducts. The model can operate both on and off-design, allowing dynamic behavior to be studied throughout the operating range of the wave rotor. The model accounts for several major loss mechanisms including finite passage opening time, fluid friction, heat transfer to and from the passage walls, and leakage to and from the passage ends. In addition it can calculate the amount of work transferred to or from the fluid when the flow in the ducts is not aligned with the passages such as occurs in off-design operation. Since it is one-dimensional, the model runs reasonably fast on a typical workstation. This article will describe the model and present the results of some transient calculations for a conceptual four-port wave rotor designed as a topping cycle for a small gas-turbine engine.