Dynamic Tip Clearance Measurements in Axial Flow Compressors

1989 ◽  
pp. 419-423
Author(s):  
C. J. Parrish
Keyword(s):  
Axial Flow ◽  
Tip Clearance ◽  
Axial Flow Compressors

scholarly journals Analysis of Efficiency Sensitivity Associated With Tip Clearance in Axial Flow Compressors

1988 ◽  
Author(s):  
Ian N. Moyle
Keyword(s):  
Axial Flow ◽  
Tip Clearance ◽  
Design Parameters ◽  
Published Data ◽  
Constant Flow ◽  
Stage Design ◽  
Axial Compressors ◽  
Sensitivity Range ◽  
Loss Method ◽  
Axial Flow Compressors

The effects of tip clearance changes on efficiency in axial compressors are typically established experimentally. The ratio of change of efficiency with change of clearance gap varies significantly for different compressors in the published data. An analysis of this sensitivity range in terms of the blade and stage design parameters was initiated. The analysis revealed that the sensitivity range largely resulted from a derivation at constant flow of the efficiency decrement. It was also found that a generalized loss method of generating the sensitivities produced a much improved correlation of the change in efficiency with change in clearance over a variety of machines, configurations and speeds.

scholarly journals Analysis of Aerodynamically Induced Whirling Forces in Axial Flow Compressors

2000 ◽  
Vol 122 (4) ◽  
pp. 761-768 ◽  
Author(s):  
Z. S. Spakovszky
Keyword(s):  
System Analysis ◽  
Axial Flow ◽  
Tip Clearance ◽  
Design Tools ◽  
Mean Flow ◽  
Blade Loading ◽  
Force Prediction ◽  
Engine Design ◽  
Comparable Magnitude ◽  
Axial Flow Compressors

A new analytical model to predict the aerodynamic forces in axial flow compressors due to asymmetric tip-clearance is introduced. The model captures the effects of tip-clearance induced distortion (i.e., forced shaft whirl), unsteady momentum-induced tangential blade forces, and pressure-induced forces on the spool. Pressure forces are shown to lag the tip-clearance asymmetry, resulting in a tangential (i.e., whirl-inducing) force due to spool pressure. This force can be of comparable magnitude to the classical Alford force. Prediction and elucidation of the Alford force is also presented. In particular, a new parameter denoted as the blade loading indicator is deduced. This parameter depends only on stage geometry and mean flow and determines the direction of whirl tendency due to tangential blade loading forces in both compressors and turbines. All findings are suitable for incorporation into an overall dynamic system analysis and integration into existing engine design tools. [S0889-504X(00)01604-4]

Rotor Whirl Forces Induced by the Tip Clearance Effect in Axial Flow Compressors

1993 ◽  
Author(s):  
Fredric Ehrich
Keyword(s):  
Experimental Data ◽  
Tangential Force ◽  
Axial Flow ◽  
Tip Clearance ◽  
Aircraft Engines ◽  
Peak Efficiency ◽  
Compressor Rotor ◽  
Strong Resemblance ◽  
Gas Turbine Compressor ◽  
Axial Flow Compressors

Abstract It is now widely recognized that destabilizing forces, tending to generate forward rotor whirl, are generated in axial flow turbines as a result of the non-uniform torque induced by the non-uniform tip-clearance in a deflected rotor — the so called Thomas/Alford force (Thomas, 1958 and Alford, 1965). It is also recognized that there will be a similar effect in axial flow compressors, but qualitative considerations cannot definitively establish the magnitude or even the direction of the induced whirling forces — that is, if they will tend to forward or backward whirl. Applying a “parallel compressor” model to simulate the operation of a compressor rotor deflected radially in its clearance, it is possible to derive a quantitative estimate of the proportionality factor β which relates the Thomas/Alford force in axial flow compressors (i.e., the tangential force generated by a radial deflection of the rotor) to the torque level in the compressor. The analysis makes use of experimental data from the GE Aircraft Engines Low Speed Research Compressor facility comparing the performance of three different axial flow compressors, each with four stages (typical of a mid-block of an aircraft gas turbine compressor) at two different clearances (expressed as a percent of blade length) — CL/L = 1.4% and CL/L = 2.8%. It is found that the value of β is in the range of +0.27 to −0.71 in the vicinity of the stages’ nominal operating line and +0.08 to −1.25 in the vicinity of the stages’ operation at peak efficiency. The value of β reaches a level of between −1.16 and −3.36 as the compressor is operated near its stalled condition. The final result bears a very strong resemblance to the correlation obtained by improvising a normalization of the experimental data of Vance and Laudadio (1984) and a generic relationship to the analytic results of Colding-Jorgensen (1990).

scholarly journals Three-Dimensional Performance Prediction of Multistage Axial Flow Compressors With a Repeating Stage Model

1999 ◽  
Author(s):  
Y. G. Li ◽  
A. Tourlidakis ◽  
R. L. Elder
Keyword(s):  
Performance Prediction ◽  
Static Pressure ◽  
Three Dimensional ◽  
Axial Flow ◽  
Correction Method ◽  
Tip Clearance ◽  
Stage Model ◽  
Inlet Velocity ◽  
Average Value ◽  
Axial Flow Compressors

In this paper, a method for the performance prediction of multistage axial flow compressors through a steady, three-dimensional, multi-block Navier-Stokes solver is presented. A repeating stage model has been developed aiming at the simplification of the required global aerodynamic boundary conditions for the simulation of the rear stages of multistage axial compressors where only mass flow rate and exit average static pressure are required. The stage inlet velocity distribution is fixed to be equal to the one calculated at the stage exit and the exit static pressure distribution is fixed to have the same shape to that at inlet but maintain its own average value. A mixing plane approach is used to exchange information between neighbouring blade rows which allows both radial and circumferential variations at both sides of the interface. A pressure correction method with the standard k–ε turbulence model is used in combination with Stone’s two step procedure for the solution of the algebraic system of the discretised equations. A global iteration is carried out in order to establish the physical consistency between the blade rows. A combination of two structured grid blocks for the rotor blade row, one for the main passage and a second for the modelling of the tip clearance, is used for a detailed representation of the leakage flows. Computational results from two methods, the first by using the repeating stage model and the second by setting stage inlet velocity profile, are presented from the analysis of the third stage of the four-stage Cranfield Low Speed Research Compressor (LSRC). Good agreements with the experimental data are obtained in terms of total pressure, static pressure and velocity distributions at the inlet, exit and interface planes proving that the repeating stage model is a very economical and accurate alternative to the very expensive complete multistage simulations.

scholarly journals Analysis of Aerodynamically Induced Whirling Forces in Axial Flow Compressors

2000 ◽  
Author(s):  
Z. S. Spakovszky
Keyword(s):  
System Analysis ◽  
Axial Flow ◽  
Tip Clearance ◽  
Design Tools ◽  
Mean Flow ◽  
Blade Loading ◽  
Force Prediction ◽  
Engine Design ◽  
Comparable Magnitude ◽  
Axial Flow Compressors

A new analytical model to predict the aerodynamic forces in axial flow compressors due to asymmetric tip-clearance is introduced. The model captures the effects of tip-clearance induced distortion (i.e. forced shaft whirl), unsteady momentum-induced tangential blade forces and pressure induced forces on the spool. Pressure forces are shown to lag the tip-clearance asymmetry, resulting in a tangential (i.e. whirl-inducing) force due to spool pressure. This force can be of comparable magnitude to the classical Alford force. Prediction and elucidation of the Alford force is also presented. In particular, a new parameter denoted as the blade loading indicator is deduced. This parameter depends only on stage geometry and mean flow and determines the direction of whirl tendency due to tangential blade loading forces in both compressors and turbines. All findings are suitable for incorporation into an overall dynamic system analysis and integration into existing engine design tools.

Viscous-Flow 2D-Analysis Including Secondary Flow Effects

2000 ◽  
Author(s):  
Reinhard Mönig ◽  
Frank Mildner ◽  
Ralf Röper
Keyword(s):  
Secondary Flow ◽  
Boundary Layers ◽  
Gas Turbines ◽  
Axial Flow ◽  
Tip Clearance ◽  
New Method ◽  
Navier Stokes ◽  
Flow Effects ◽  
End Wall ◽  
Axial Flow Compressors

During the last few decades extremely powerful Quasi-3D codes and fully 3D Navier-Stokes solvers have been developed and successfully utilized in the design process and optimization of multistage axial-flow compressors. However, most of these methods proved to be difficult in handling and extremely time consuming. Due to these disadvantages, the primary stage design and stage matching as well as the off-design analysis is nowadays still based on fast 2D methods incorporating loss-, deviation- and end wall modeling. Only the detailed 3D optimization is normally performed by means of advanced 3D methods. In this paper a fast and efficient 2D calculation method is presented, which already in the initial design phase of multistage axial flow compressors considers the influence of hub leakage flows, tip clearance effects and other end wall flow phenomena. The method is generally based on the fundamental approach by Howard and Gallimore (1992). In order to allow a more accurate prediction of skewed and non-developed boundary layers in turbomachines an improved theoretical approach was implemented. Particularly the splitting of the boundary layers into an axial and tangential component proved to be necessary in order to account for the change between rotating and stationary end walls. Additionally, a new approach is used for the prediction of the viscous end wall zones including hub leakage effects and strongly skewed boundary layers. As a result, empirical correlations for secondary flow effects are no longer required. The results of the improved method are compared with conventional 2D-results including 3D loss- and deviation-models, with, experimental data of a 3-stage research compressor of the Institute for Jet Propulsion and Turbomachinery of the Technical University of Aachen and with 3D Navier-Stokes solutions of the V84.3A compressor and of a multi-stage Siemens research compressor. The results obtained using the new method show a remarkable improvement in comparison with conventional 2D-methods. Due to the high quality and the extremely short computation time the new method allows an overall viscous design of multistage compressors for heavy duty gas turbines and aeroengine applications.

Fast Response Tip Clearance Measurements in Axial Flow Compressors—Techniques and Results

1990 ◽  
Vol 204 (1) ◽  
pp. 51-55
Author(s):  
C J Parrish
Keyword(s):  
Rotor Blade ◽  
Axial Flow ◽  
Fast Response ◽  
Tip Clearance ◽  
Measuring System ◽  
Blade Tip ◽  
Important Means ◽  
Axial Flow Compressors

As part of an investigation of the effects of tip clearance performance of development axial flow compressors, a system for detecting rotor blade tip rubs has been developed and a tip clearance measuring system modified to detect clearance changes at a bandwidth of 500 Hz. Mean clearance changes have been measured as well as changes during surge. Rotor orbit has also been investigated and the system has become an important means of monitoring rotordynamic behaviour. Subharmonic components of rotor orbit have been discovered.

Plasma spray parameters to optimize the properties of abrasion coating used in axial flow compressors of aero-engines to maintain blade tip clearance

2020 ◽  
Vol 33 ◽  
pp. 5691-5697 ◽  
Author(s):  
Priyabrata Mallick ◽  
Bikram Behera ◽  
Swadhin Kumar Patel ◽  
Biswajit Swain ◽  
Rakesh Roshan ◽  
...  
Keyword(s):  
Plasma Spray ◽  
Axial Flow ◽  
Tip Clearance ◽  
Spray Parameters ◽  
Blade Tip ◽  
Aero Engines ◽  
Blade Tip Clearance ◽  
Axial Flow Compressors
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