Single-passage solution of three-dimensional unsteady flows in a transonic fan rotor

Abstract

Calculations of unsteady turbomachinery flows using conventional time domain methods typically would lead to the use of multiple passages/whole annulus owing to the required direct periodic condition. This makes conventional unsteady solutions extremely time consuming and is one of the major difficulties in applying unsteady calculations in a blading design environment. A single-passage approach to three-dimensional unsteady Navier-Stokes calculations using the Fourier series based shape correction method has been developed. The shape correction method gives a single-passage solution to unsteady flows in blade rows under multiple disturbances with arbitrary interblade phase angles. Therefore the computing time can be dramatically reduced. A case study for a transonic fan rotor subject to long-scale circumferential inlet distortions shows that a factor of 5 speed-up could be achieved. Detailed comparisons in both unsteady and time-averaged flow results between the single-passage and multiple-passage solutions demonstrate the validity and effectiveness of the present single-passage approach. A further calculation of a transonic rotor simultaneously under the influences of both upstream and downstream blade rows also shows the capability of the shape correction method in dealing with multiple disturbances.