Session: 37-04 Unsteady Flow Modeling

Paper Number: 84388

84388 - Evaluation of Various Numerical Methods for Blade Row Interaction in Turbomachinery 

The flow within turbomachinery is inherently unsteady, and the unsteady rotor-stator interaction usually has a large effect on performance in multistage turbomachines. However, fully unsteady simulations are still too time-consuming for use in turbomachinery routine design, thus, the steady mixing plane method that neglects the interaction is widely used. Some reduced-order unsteady methods, such as harmonic balance (HB) method and space-time gradient (STG) method, have been proposed to simulate the unsteady periodic flow and reduce CPU time consumption significantly with sufficient accuracy.

In this work, four mixing-plane methods, HB method and STG method are implemented into the open source CFL3D solver, which is a NASA open-source RANS solver based on structured-grid cell-centered finite volume method. The four mixing-plane methods include: Conservative Coupling by Pitchwise Rows (CCP), Local Conservative Coupling (LCC) method, Momentum Average (MA) method and Entropy Average (EA) method. For multi-rows turbomachinery unsteady simulation, a rotation interpolation interface is implemented in to CFL3D to save the CPU time consumption, which rotation grid method is not used. In order to evaluate the effect of these methods on predicting unsteady rotor-stator interaction, three cases are simulated, which include a quasi 2D high pressure compressor, NASA stage35 compressor and a 1.5 stage compressor.

Considering the governing equations, the temporal derivation term is considered as a coupling source term of different time for HB method, and the temporal derivation term is replaced by a space derivation source term for STG method. Therefore, they all take into account the unsteady effect of time without explicit inclusion of the temporal derivation term in the governing equations. Both the high-order HB and STG methods have the similar ability as the conventional unsteady simulation to simulate the wake that transmitted from the upstream to the downstream, which steady mixing-plane methods cannot. For the numerical results of 1.5 stage compressor, it is obviously that the wake of the first row can reach the third blade row. HB and STG method can also clearly capture the phenomenon. To evaluate the blade row interaction, the proper orthogonal decomposition (POD) and Fourier analysis method are used to analyze the interaction in different blade rows.

Presenting Author: Xiaosong Yong Beihang Universit

Presenting Author Biography: Mr YONG is a PhD student at Beihang University. His main interest includes unsteady blade row interaction, machine learning and CFD solver development.

Authors:

Yangwei Liu Beihang University
Xiaosong Yong Beihang Universit
Yumeng Tang Beihang University