Numerical Investigation of Centerbodiless RDE Design Variations

Abstract

The pressure gain of detonation has great potential to increase efficiency of cycles involving combustion. Rotating detonation engines (RDEs) have a great deal of promise as a detonation based combustor. The RDE’s advantages over current pulsed detonation cycles include needing only a single initiation, having a more uniform exhaust pressure, compact design, and capability to process high flow rates. However, without consideration for pressure losses due to friction or shock strength, it is possible to lose the efficiency advantages RDEs have over conventional combustion. Some recent numerical studies have shown it may be possible to ignite an RDE that has only the outer wall, with air going through the center instead of a centerbody. These centerbodiless RDE Designs may entrain flow and impart momentum to more air, which may increase the total propulsive efficiency. In addition, their unique design with fewer walls for reflection may result in fewer reversals and blow-outs of the RDE. This may expand the range of operation for certain applications. A numerical study using a Reynolds-Averaged Navier-Stokes (RANS) Computational Fluid Dynamics (CFD) program Fluent, by ANSYS is being performed to test three dimensional (3D) configurations of centerybodyless RDE. The effect of various alterations to the design will be studied, including hydrogen injection hole size alteration, longitudinal walls, and an ejector. A simple Spalart-Allmaras turbulence model will be used to better simulate mixing of hydrogen and air. Detonation will test for steady operation for multiple cycles.