Blade tip rubbing stress prediction. Final report

Technical Report · Tue Jan 01 04:00:00 EST 1991

OSTI ID:5753692

Davis, G A; Clough, R C

An analytical model was constructed to predict the magnitude of stresses produced by rubbing a turbine blade against its tip seal. This model used a linearized approach to the problem, after a parametric study, found that the nonlinear effects were of insignificant magnitude. The important input parameters to the model were: the arc through which rubbing occurs, the turbine rotor speed, normal force exerted on the blade, and the rubbing coefficient of friction. Since it is not possible to exactly specify some of these parameters, values were entered into the model which bracket likely values. The form of the forcing function was another variable which was impossible to specify precisely, but the assumption of a half-sine wave with a period equal to the duration of the rub was taken as a realistic assumption. The analytical model predicted resonances between harmonics of the forcing function decomposition and known harmonics of the blade. Thus, it seemed probable that blade tip rubbing could be at least a contributor to the blade-cracking phenomenon. A full-scale, full-speed test conducted on the space shuttle main engine high pressure fuel turbopump Whirligig tester was conducted at speeds between 33,000 and 28,000 RPM to confirm analytical predictions.

• Research Organization: Rockwell International Corp., Canoga Park, CA (USA)
• OSTI ID: 5753692
• Report Number(s): N-91-18435; NASA-CR--184100; NAS--1.26:184100; RI/RD--91-114; CNN: NAS8-36361
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
421000* -- Engineering-- Combustion Systems
DOCUMENT TYPES
FRICTION
HYDRAULIC TURBINES
MACHINERY
MATHEMATICAL MODELS
PROGRESS REPORT
PUMP TURBINES
STRESS ANALYSIS
TURBINE BLADES
TURBINES
TURBOMACHINERY