Stall Characteristic Prediction in a Single Passage of a Transonic Axial Compressor Rotor
[Technical Report, Master's Thesis]
Naval Postgraduate School
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This study expands on previous work related to computational fluid dynamics CFD modeling of a single blade passage of the NPS Military Fan NPSMF with a particular focus on improving numerical predictions of rotor performance and resolving flow features near stall. A previous CFD model of the NPSMF is examined through a mesh sensitivity study in order to better resolve flow through the device in the near-stall region. Additionally, the existing gas path geometry is reconstructed to provide a higher-quality periodic boundary for simulations of a single blade passage and to introduce a method for rapid implementation of casing treatments in support of concurrent and future studies to improve the NPSMFs stall margin. The improved mesh and gas path geometry are then simulated for three tip-clearance cases zero, narrow, and wide using ANSYS CFX and compared to previous numerical predictions and experimental data from the narrow tip-clearance case to highlight improvements to the CFD model. The updated CFD model under-predicts the stall point compared to the experimental data but shows significant improvement over previous work. Flow visualizations from the three tip clearance cases are compared to each other to highlight tip-clearance effects within the NPSMF flow field, and a stalled case from the wide tip-gap is used to illustrate the tip-blockage mechanism responsible for stall.
- Hydraulic and Pneumatic Equipment
- Fluid Mechanics