Validation of a Throughflow Time-Marching Finite-Volume Solver for Transonic Compressors

Abstract

An improved throughflow method to treat transonic viscous flows with shocks, using a finite-volume time-marching solver, is presented. Effects due to deviation, secondary losses, endwall skin friction and spanwise mixing are modelled. An alternative blade blockage is used to better take into account the effect of the blade on the transonic passage flow. A theoretical and numerical study of the axisymmetric shock showed that it is treated as a normal blade passage shock by the blade row model. Two different techniques to solve the numerical problems associated with the leading edge singularity due to incidence are investigated. The computation of an entire speed-line for a three stage transonic fan has been conducted in order to further calihrate and validate the various models. The validation showed that the solver is capable of giving a reasonable meridional picture of the transonic flow field for different operating points.

A time-marching throughflow model and its application in transonic axial compressor

“…The above system of equations can be obtained by circumferentially averaging the Navier-Stokes equations neglecting the circumferentially non-uniform terms and viscous terms [2,3]. The inviscid and viscous blade forces responsible for the flow deflection and losses respectively need to be modeled.…”

“…where ( ) (1) w ρ r is the momentum computed in the first step, and ( ) (2) w ρ r is the ultimate momentum in the whole time step. In other words, (5) is firstly solved and then (9) is used to revise the momentum in (5).…”

Evaluation of Higher-Order Terms in the Throughflow Approximation Using 3D Navier-Stokes Computations of a Transonic Compressor Rotor

“…The numerics of the code are similar to those of the three-dimensional solver previously described. Several transonic test cases were used for the validation of the code (Baralon et al, 1998). The solver has been modified so as to allow the inclusion of all the terms derived from the averaged 3D solution.…”

Modeling of 3-D losses and deviations in a throughflow analysis tool

“…The throughflow analysis tool used in the present work is based on the Euler equations [1,11] vier-Stokes equations [9]. Such models allow to calculate the flow field whatever the flow regime is, they are able to perform transient simulations and they can cope with 2-D flow recirculations.…”

“…The inviscid blade force is computed by an additional time-dependent equation [1], while the viscous blade force is calculated by a distributed loss model and empirical correlations. In order to avoid loss generation by the inviscid blade force, its direction is chosen orthogonal to the flow field.…”