The present experimental study demonstrates the effects of clean and distorted inflow conditions on the performance and nature of stall inception in a single stage axial flow fan. A 90° distortion screen located upstream of the rotor leading edge was rotated up to 40 per cent of the rotor speed in the clockwise (co-rotation) and counterclockwise (counter-rotation) directions to generate dynamic inflow distortion. It was observed that the stall margin deteriorated substantially under co-rotating inflow distortion as compared to counter-rotating inflow distortion. The degradation in stall margin was about 15 per cent and 1.98 per cent under co- and counter-rotating inflow distortions, respectively. Tip injection was used as a means of enhancing the fan performance under distorted inflow. With tip injection under co-rotating inflow distortion, about 2.8 per cent improvement in stall margin was observed. The improvement in stall margin under counter-rotating inflow distortion with tip injection was 2.98 per cent. The unsteady static pressure traces show clear differences in the nature of stall inception under co- and counter-rotating inflow distortions. The stall inception occurs through long-length-scale disturbances under co-rotating inflow distortion, while the mode of stall inception under clean flow and counter-rotating inflow distortions was through short-length-scale disturbances. The nature of stall inception under dynamic inflow distortion with tip injection remains the same as without tip injection.
|Number of pages||16|
|Journal||Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy|
|Publication status||Published - 01-01-2010|
All Science Journal Classification (ASJC) codes
- Energy Engineering and Power Technology
- Mechanical Engineering