Rotor-Stator Flow Interaction Simulation via Coupled CFD
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Solution Overview
Problem
Conventional computational fluid dynamics (CFD) methods struggle to accurately simulate rotor-stator unsteady turbulent flow interactions in turbomachinery due to high computational burdens and limitations in capturing both large-scale periodic unsteadiness and small-scale turbulence eddies, especially in realistic turbomachinery configurations with multiple blade passages.
Innovation Solution
A two-scale CFD approach is implemented, using a coarse mesh to discretize multiple blade passages and fine meshes in selected regions for large eddy simulations, with ensemble-averaged flow field simulations coupled to derive unsteady turbulence stress terms, reducing computational demands while maintaining accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional LES approaches are extended to simulate rotor-stator flow interactions, then turbulence eddies can be resolved, but computational burden becomes prohibitively high
Solution Approach 1:
The computational domain is segmented into multiple sub-domains corresponding to individual blade passages. Each sub-domain is simulated independently with its own LES, allowing the total computational burden to be distributed across multiple smaller parallel simulations rather than one large sequential simulation.
Solution Approach 2:
Instead of performing full LES across the entire 360° annulus domain, the method applies LES only to representative blade passages (partial action). The results from these partial simulations are then used to construct the complete flow field, reducing computational requirements while maintaining accuracy.
2Reliability
If a whole 360° annulus domain is adopted for realistic rotor-stator blade count ratios, then complete flow interaction can be captured, but computational domain size becomes excessively large
Solution Approach 1:
The LES methodology developed for a single blade passage is made universal and applied to multiple blade passages through periodic boundary conditions and domain replication. This allows the same computational approach to handle both single-passionage and multi-passionage scenarios without redesign.
Solution Approach 2:
Instead of simulating the entire 360° annulus domain with all blade passages, the method copies the flow solution from a representative blade passage to other passages using periodicity assumptions. This creates a complete flow field representation without the computational cost of resolving every passage.
3Measurement precision
If fine meshes are used throughout the entire domain for LES, then turbulence resolution is improved, but computational cost increases prohibitively
Solution Approach 1:
Fine mesh resolution is applied locally only where turbulence effects are most critical (e.g., near blade surfaces, trailing edges, and in the immediate wake regions), while coarser mesh is used in regions where turbulence intensity is lower. This maintains turbulence resolution accuracy where needed while reducing overall computational cost.
Solution Approach 2:
Full fine-mesh LES is applied only to selected critical regions and blade passages rather than uniformly across the entire domain. This partial application of fine meshing provides sufficient turbulence resolution for design-critical areas while avoiding the prohibitive cost of全域 fine meshing.
Data Source
AI summary
A computer-based method of simulating rotor-stator unsteady turbulent flow interaction in turbomachinery, which includes performing CFD ensemble-averaged flow field simulation over the coarse mesh and performing CFD large eddy simulations over the fine meshes, the ensemble-averaged and large eddy simulations being coupled to each other, and the large eddy simulations of the regions of the selected blade passages being used to derive unsteady turbulence stress terms in the ensemble-averaged simulation for corresponding regions of the blade passages of the first and second rows without fine meshes.