Abstract
The main objective of the following paper is to identify and elaborate the parameters that have a significant impact on the operational characteristics of the Pressure Wave Supercharger also known as Comprex. This type of supercharger can transfer some of the energy from the exhaust gases in the form of pressure waves, directly to the fresh air entering the internal combustion engine. The device is in fact a pressure exchanger with a greater adiabatic efficiency than other well known steady-flow machine like compressors or turbochargers. Besides other advantages like fast response on acceleration (no turbo lag) and relative high boost pressure, even when the engine is running at partial loads and low speeds, the PWS has also some shortcomings in matching the speed and load requirements for the entire operational range of the engine. The reason for this problem is an inadequate speed of the supercharger rotor which can lead to a poor distribution of the pressure-wave phenomena that can compromise the performance of the engine due to an inappropriate gas exchange at he inlet phase.In order to determine the optimal speed of the Comprex, the authors focused on operating parameters like pressure and temperature that have a fundamental influence on the processes taking place inside the PWS. The study was made with the help of a commercially CFD software, which enabled a precise simulation of the high pressure part of the supercharger.
Keywords: Rotor, shock wave, wave speed, boundary conditions, pressure ratio