Showing papers on "Tip clearance published in 1984"

Performance of a high-work low aspect ratio turbine tested with a realistic inlet radial temperature profile

Abstract: Experimental results are presented for a 0.767 scale model of the first stage of a two-stage turbine designed for a high by-pass ratio engine. The turbine was tested with both uniform inlet conditions and with an inlet radial temperature profile simulating engine conditions. The inlet temperature profile was essentially mixed-out in the rotor. There was also substantial underturning of the exit flow at the mean diameter. Both of these effects were attributed to strong secondary flows in the rotor blading. There were no significant differences in the stage performance with either inlet condition when differences in tip clearance were considered. Performance was very close to design intent in both cases.

Gas turbine engine having a minimal blade tip clearance

Abstract: A gas turbine engine is so constructed that the clearance or gap between the rotor and stator, especially at the outer diameter range of a radial flow end stage, is optimally maintained under all operating conditions. For this purpose the housing in the axial-flow/radial-flow compressor is constructed as a two shell housing. The outer housing shell is mounted as part of the engine structure, whereby the inner housing shell is exposed substantially only to forces or loads caused by compressor fluid flow. The material of the outer housing shell has a heat expansion coefficient in the axial direction of the rotational engine axis, which is distinctly lower than the heat expansion coefficient of the material of the compressor rotor. The heat expansion coefficient of the material of the inner housing shell is lower in the circumferential direction and approximately equal in the axial direction relative to the heat expansion coefficient of the rotor. The fixed bearing of the compressor rotor is arranged in the zone of the compressor inlet.

Application of a quasi-3D inviscid flow and boundary layer analysis to the hub-shroud contouring of a radial turbine

Abstract: Application of a quasi-3D approach to the aerodynamic analysis of several radial turbine configurations is described. The objective was to improve the rotor aerodynamic characteristics by hub-shroud contouring. The approach relies on available 2D inviscid methods coupled with boundary layer analysis to calculate profile, mixing, and endwall losses. Windage, tip clearance, incidence, and secondary flow losses are estimated from correlations. To eliminate separation along the hub and blade suction surfaces of a baseline rotor, the analysis was also applied to three alternate hub-shroud geometries. Emphasis was on elimination of an inducer velocity overshoot as well as increasing hub velocities. While separation was never eliminated, the extent of the separated area was progressively reduced. Results are presented in terms of mid-channel and blade surface velocities; kinetic energy loss coefficients; and efficiency. The calculation demonstrates a first step for a systematic approach to radial turbine design that can be used to identify and control aerodynamic characteristics that ultimately determine heat transfer and component life. Experimentation will be required to assess the extent to which flow and boundary layer behavior were predicted correctly.

Tip clearance flow in a compressor rotor passage at design and off-design conditions

Abstract: The flow field in the tip clearance region of a compressor rotor at an off-design condition is reported in this paper. The earlier data at the design condition has also been re-interpreted and correlated with the blade and the flow parameters. The measurements inside the rotor tip region are acquired using a miniature hot wire sensor of 'V' configuration. The instantaneous velocity data is analyzed by the ensemble averaging technique to derive the blade-to-blade velocity field at various axial and radial locations between the rotor tip and the casing. The flow and the blade pressure data at the design condition are compared with the data at the off-design condition (lower blade loading). In addition to a reduction in the leakage velocities, its chordwise variation is also altered substantially at the lower blade loading.

Three-dimensional viscous flow analysis for centrifugal impellers

Abstract: A SPACE-MARCHING Navier-Stokes solver is used to -TjLsimulate three-dimensional viscous flows in centrifugal impellers. This solver employs a finite volume integration procedure for the partially parabolic equations written in arbitrary curvilinear coordinates. The solution is achieved using a multiple-pass forward-marching iteration scheme. The accuracy of the analysis method is verified using impeller intrapassage laser-velocimeter data. The method is demonstrated to predict the jet/wake flows characteristic of centrifugal impellers. The result clearly shows the importance of modeling the blade tip clearance flow accurately.

Radiator for automobile

Abstract: PURPOSE:To ensure that air flow resistance is reduced at the time of high- speed running and the quantity of forced air flow is enlarged at the time of low- speed running, by a method wherein the spacing between a cooling fan and a main body of a radiator is enabled be varied CONSTITUTION:In low-speed running or idling, when a motor M is driven to rotate the cooling fan 2, air is sucked from the front side of the radiator by the fan 2 and is blasted to the side of the motor M Due to a reaction force of the blasting, the fan 2 is moved to the solid-line position, and is rotated in the condition wherein the center thereof makes contact with a stopper 8 Therefore, the tip clearance between the fan 2 and a shroud 3 is reduced, thereby increasing the air intake quantity and enhancing heat transfer efficiency of the radiator At the time of high-speed running, the motor M is stopped, the fan 2 is returned to the dotted-line position due to the pressure of the airflow 9 generated during the running of the vehicle, whereby the tip clearance is enlarged to reduce air flow resistance Accordingly, the heat transfer efficiency of the radiator can be maintained to be high even at the time of high-speed running

Device for measuring tip clearance of blade

Abstract: PURPOSE:To measure easily a tip clearance of blade by providing an operating device which emits two beams inclined mutually toward the tip of blade of a rotor, measures a time interval between signals of a reflected light from the tip, and calculates the tip clearance basing on its measured value. CONSTITUTION:When a light is emitted from light sources 5, 6, two beams S1, S2 are irradiated continuously onto the circumference through which a blade 2 passes, in a state inclined by a lens 19 of an optical probe 7, through optical fibers 16, 17, respectively, and when the blade 2 moves and comes, the beam S1 from the optical fiber 16 irradiates the end of the blade 2, and when the blade 2 further moves, the beam S2 from the optical fiber 17 irradiates the end of the blade 2, and both of them are reflected to the lens 19. Subsequently, the beams S1, S2 become parallel beams by the lens 19, are led to an optical filter 10 by an optical fiber 18, sent to each photoelectric converting device 11, and in this device, the respective signals are converted to electrical signals, also a pulsative signal is made by each waveform shaping device 12, and its signal is sent to a signal processing device 13.

A Study of the Prediction of Tip and Seal Clearances and Their Effects in Gas Turbine Transients

Abstract: Clearances of compressor and turbine blade tips and seals alter during and following speed transients. These changes affect the performance of the components and hence of the engine.This paper describes models for the prediction of blade tip clearance changes and seal clearance changes. These models have been applied to the H.P. Compressor and H.P. Turbine and to two seals controlling air flows in a Two-spool Bypass Engine. The predicted acceleration rates appear to be more influenced by the changes in the seal clearances than by the tip clearance changes.The increases in computing time in the engine transient program which result from inclusion of the model are acceptable.Copyright © 1984 by ASME

Three-dimensional viscous flow analysis for centrifugal impellers

Abstract: A SPACE-MARCHING Navier-Stokes solver is used to -TjLsimulate three-dimensional viscous flows in centrifugal impellers. This solver employs a finite volume integration procedure for the partially parabolic equations written in arbitrary curvilinear coordinates. The solution is achieved using a multiple-pass forward-marching iteration scheme. The accuracy of the analysis method is verified using impeller intrapassage laser-velocimeter data. The method is demonstrated to predict the jet/wake flows characteristic of centrifugal impellers. The result clearly shows the importance of modeling the blade tip clearance flow accurately.