A Two-Dimensional Computer Simulation of Unsteady Flow During the Intake-Compression Stroke of a Rotary Engine.

A two-dimensional computer simulation study is developed to obtain efficient understanding of unsteady flow behaviors during the intake-compression stroke of a rotary engine. Emphasis is put on describing swirling flow features as a function of the rotor geometry and operating conditions. The system of the compressible N-S equations is solved by applying the Beam and Warming method with the DD-ADI algorithm. Second and fourth-order nonlinear artificial dissipation terms are added in the scheme with minmod-type limiters. Since the convective acceleration of the gas is considerably weak, a special treatment for the pressure description is required along the rotor boundary wall. Various flow patterns are presented satisfactorily, which are constituted of vortices generated in the intake process and secondary vortices developed by the rotor movement. Their features agree well with the experimental observations made separately by the authors, and a prospective view to design more efficient engines is obtained.