Abstract
KEYWORDS
Comprex®, wave rotor, shock reflection, boundary conditions, pressure ratio.
ABSTRACT
This paper presents a detailed simulation of the phenomenon found inside the Pressure Wave Supercharger. The PWS, also known as Comprex® or Hyprex®, is an unsteady-flow device that can transfer energy directly, by means of pressure waves, between the fresh air and the exhaust gasses from an Internal Combustion Engine. In the wave rotor, these two fluids with different pressures are brought into direct contact. Then pressure exchange occurs faster than mixing. This type of supercharger has a higher isentropic efficiency than steady-flow devices, like compressors or diffusers, but may be more challenging to control. Comparative to the turbocharger, the PWS has important advantages like fast response on accelerations, (no turbo lag), and can deliver higher boost pressures at partial engine loads and low engine speeds. In the past, unsteady-flow process simulation was very inaccurate, time consuming and labor intensive. Recently, because of the increase in calculation power of the computers and more accurate commercially available software packages, significant progress was made in understanding the complex wave phenomena. Using CFD software like FLUENT, the authors were able to simulate the unsteady nature of the flow inside the PWS.