Showing papers on "Tip clearance published in 1969"

Effect of rotor tip clearance on the performance of a 5-inch single stage axial flow turbine

Abstract: Turbine efficiency decreased linearly with increasing rotor tip clearance. Static efficiency decreased 20 percent (0. 79 to 0. 63) as rotor tip clearance was increased from 1. 2 to 8. 0 percent of passage height. Rotor exit flow survey data are presented in addition to performance data. Comparison of data with three reference turbines substantiated the results obtained and indicated that rotor tip clearance effects are larger for a reaction turbine than for an impulse turbine. EFFECT OF ROTOR TIP CLEARANCE ON THE PERFORMANCE OF A 5-INCH SINGLE-STAGE AXIAL-FLOW TURBINE by Donald E. Holeski and Samuel M. Futral, Jr. Lewis Research Center

Determination of the design parameters for optimum heavily loaded ducted fans

Abstract: : A single-rotation ducted fan of highest induced efficiency is characterized by an ultimate wake vortex system shed from the blade trailing edges whose apparent motion is that of rigid helical surfaces. In addition and concentric with this inner sheet system there is a cylindrical surface of helical vortex filaments shed from the duct trailing edge. For zero hub diameter and neglecting compressibility, viscosity, and tip clearance, a consistent mathematical model of the constant-diameter vortex wake is developed and the compatibility relationships to be satisfied are presented. It is shown that the wake vorticity and the velocity distribution in the wake, for all loadings from the lightly loaded limit to the heavily loaded static thrust condition may be extracted from the lightly loaded result through the use of a simple algebraic scale factor. The performance parameters, thrust, power and blade bound vortex strength, are thus expressed in terms of a lightly loaded solution for a given freestream velocity, blade tip speed, blade number and the loading parameter. The lightly loaded case is compared to existing theoretical and experimental results. Some sample results for heavily loaded performance parameters and design parameters are presented and compared to the exact results for a heavily loaded ducted fan with an infinite number of blades. Results for the heavily loaded system over a broad range of conditions are presented.

The Effect of Inducer Tip Clearance on Suction Performance

Abstract: The effect of the inducer tip clearance on the pump suction performance is investigated with an inducer and two main impellers having different eye diameters. The experiment revealed the following : (1) When the eye diameter of the main impeller is nearly equal to the normal inducer tip diameter, the pump suction performance decreases with increasing tip clearance.(2) When the eye diameter is 90% of the normal inducer tip diameter, the pump suction performance scarcely changes with increasing tip clearance, provided that the inducer tip diameter is larger than the eye diameter.(3) When an inducer is followed by a different main impeller, the pump suction performance becomes different.Besides, the reason for the above relationship between the tip clearance and the pump suction performance is studied with the velocity and total head distributions measured at the inducer outlet.