APPLICATION OF THE BLUNT TRAILING EDGE BLADE CONCEPT TO LOW HUB TIP RATIO TRANSONIC-SUPERSONIC COMPRESSORS.

Abstract : The report reviews cascade tests made on blunt trailing edge blades in the supersonic and subsonic ranges, as well as a paper study for a Mach 2, 0.5 hub to tip ratio supersonic rotor now being built. In the supersonic range, three bladings, corresponding to the mid section blading of existing rotors were tested. The tests show that care must be exercised when translating cascade data into rotor performance; satisfactory operation of the blunt trailing edge blading is obtained with Mach number as high as 1.7; longer passage and thinner blades lead to better performances. In the subsonic range, a loss correlation is proposed for partly slotted stator blades, indicating that slot effectiveness is a strong decreasing function of aspect ratio. The rotor paper design investigates the effect of axial inlet Mach number, enthalpy and entropy gradients, radius of curvature, contraction. A final design is obtained, which is described in detail. The report is concluded by a description of the R-4 compressor test rig being built to test rotor and stages of performance similar to the one of the rotor presented. (Author)