Mode-matching Strategies in Slowly Varying Engine Ducts

This report forms, in two parts, deliverable D2.14 of the TurboNoiseCFD project. It describes the recommended innovative “triple plane pressure” in-duct matching strategy (TPP) at inlet and bypass duct side, and it describes in detail the newly developed and favourably tested CAA code for the propagation and radiation problem at the exhaust side. Due to the presence of the jet, this solution is also innovative. Both parts are written independently by the partners ISVR and TUE, although as a conclusion, in part II, the joint case study of a full calculational chain, from CFD data via the bypass duct into the far field radiation, is presented. In the by-pass duct TUE’s and ISVR’s propagation codes are compared. It is shown that the TUE semi-analytical multi-modal multiple scales solution for sound propagation in ducts compares extremely well with ISVR’s CAA solution. This is very important for the reliability of the matching method, which is based on this multi-modal multiple scales solution.