The Effects of Incidence Angle and Free Stream Turbulence on the Performance of a Variable Geometry Two-Dimensional Compressor Cascade at High Reynolds Numbers
Abstract
For this investigation, a seven-blade cascade of NACA 65-A506 airfoils with two inch chord, aspect ration of one, and solidity of 1.5 was used. This cascade used porous side wall suction to establish two-dimensional flow conditions. Flow Unit Reynolds numbers exceeding 2.5 million foot, and average free stream turbulence levels of 1% and 7% were used. Cascade geometry was varied in a manner similar to that used in current variable stator designs: maintaining axial direction and blade spacing constant, while varying incidence angle, stagger angle, and angle of attack. Incidence angles of -3, 0, and +3 deg. were investigated. Total pressure loss coefficient decreases through the cascade and may increase in the wake as incidence angle or free stream turbulence increase. The change in loss coefficient with increasing incidence was determined to be insignificant when compared with the change as a result of increased free stream turbulence. Blade suction surface pressure coefficients decrease sharply along the first 30% chord as incidence increases. The suction surface pressure coefficients show a uniform increase across the blade center span with additional free stream turbulence. Increases in incidence and free stream turbulence result in thicker boundary layers and suggest both earlier transition and intermittent separation on the forward half of the blade. Evidence also suggests that the location of the minimum loss incidence angle may change with additional free stream turbulence. Keywords: Compressor blades; Pressure distribution, Cascades fluid dynamics; Cascade structures; Boundary layer, Theses.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1988
- Accession Number
- ADA202650
Entities
People
- Edward M. Poniatowski
Organizations
- Air Force Institute of Technology