On the calculation of the unsteady compressible flow through an N-branch junction

Abstract

This paper presents the generalization of the ‘branch superposition method’ (BSM) for the computation of the unsteady compressible flow through an N-branch junction. In the case of a perfect gas flow in a three-branch junction, a mathematical study of the system of equations resulting from the combination of the characteristic relations and the boundary conditions is investigated. This clearly shows many possible solutions, including non-physical ones. The algorithm of the BSM is then extended to the case of an N-branch junction. The numerical calculation of unsteady compressible flow through three-branch and four-branch junctions by this method is compared with experimental measurements.