Computational Investigation of the Effects of Casing Treatments on the Performance of a Turbofan

Computational Investigation of the Effects of Casing Treatments on the Performance of a Turbofan

Weiyang Lin

For fans and compressors in air-breathing propulsion engines, the instabilities, which limit the pressure ratio available from design, are typically manifested as varying degrees of rotating stall or surge. Stall in terms of a single blade usually means separation of the incoming flow, which often occurs on the suction side. The interactions between multiple blades, however, make the overall behavior of the stall of a compressor much more complicated.

Significant research has been carried out to investigate the onset of stall, and more often than not, the tip clearance flows were found guilty. Figure 1 below is a simulation result of the tip clearance flow when the fan stage is being operated at near-stall condition. Figure 2 represents a method to improve stall margin; that is, by adding circumferential grooves to the casing. Figure 3 represents the performance enhancement by single casing grooves at different locations. 

Figure 1. Tip leakage flow of the smooth wall case at near stall

Figure 2. General layout of grooves and associated parameters (from Wisler et al. (1974))

Figure 3. Stall margin improvement by single grooves

The following is a video showing the effect of grooves on the flow. Simulation results from Tenasi. 

For more information, refer to the following documents and/or contact the author.

1. Max D. Collao, Robert S. Webster, Kidambi Sreenivas, and Weiyang Lin. "Computational Study of the Effects of Protruding Studs Casing Treatment on the Performance of an Axial Transonic Turbofan", 52nd AIAA/SAE/ASEE Joint Propulsion Conference, Propulsion and Energy Forum, (AIAA 2016-4646)

2. Lin, W., "Computational Investigation of the Effects of Casing Treatments on the Performance of a Turbofan," M.S. Thesis, The University of Tennessee at Chattanooga, August 2013. [Download Link 1 Link 2]

3. Lin, W., Sreenivas, K., Webster, R.S., and Hyams, D.G., "Effect of Casing Groove Locations on the Performance of an Axial Flow Stage," 49th AIAA/ASME/SAE/ASEE Joint Propulsion Conference. San Jose, CA, July 2013, AIAA Paper 2013-3632. [Download Link 1 Link 2]

4. Lin, W., Sreenivas, K., Webster, R., Hyams, D.G., "Effect of Casing and Tip Modifications on the Performance of an Axial Flow Stage," AIAA Paper 2012-0475, 50th AIAA Aerospace Sciences Meeting, 9 - 12 January 2012, Nashville, TN. [Download Link 1 Link 2]

5. Lin, W., Presentation, June 18, 2013

Picture hung at the SimCenter [Open Link]

Results shown in the SimCenter calendar in 2012

Results shown in the SimCenter calendar in 2014

Poster on UTC research day in 2012