Numerical investigation of surge prediction in a transonic axial compressor with a hybrid BDF/Harmonic Balance Method

Abstract

This paper aims at evaluating an efficient combination of a hybrid Backward Difference Formula/Harmonic Balance Method and the necessary time dependent exit boundary condition for the prediction of the performance line and ultimately surge line in a transonic one stage axial compressor (Stage 35) designed and measured at NASA Glenn Research Center. The agreement of the total pressure ratio, total temperature ratio as well as the efficiency curve with the experimental findings are encouraging. The results of the proposed methodology compare very well with the URANS predictions of Herrick et al. albeit the calculation is more efficient. While the prediction of the performance line in the stabile regime can be predicted by the classical Harmonic Balance Method (HBM), the investigation of strong off-design conditions, a quasi-periodic extension of the HBM is necessary. In addition, the mass flow rate and the exit pressure are no longer constant in time in this flow field an appropriate boundary condition is required for the successful simulation of this flows. Using this features the prediction of the surge behavior has been computed and a realistic flow pattern has been obtained. The computational time extents over more than 50 revolutions in order to capture the surge frequency of the compressor.