Forcing Function Effects on Rotor Periodic Aerodynamic Response

1991 ◽  
Vol 113 (2) ◽  
pp. 312-319 ◽  
Author(s):  
S. R. Manwaring ◽  
S. Fleeter
Keyword(s):  
Axial Flow ◽  
Unsteady Aerodynamics ◽  
Harmonic Response ◽  
Inlet Distortion ◽  
Forcing Function ◽  
Reduced Frequency ◽  
Blade Row ◽  
Forcing Functions ◽  
Series Of Experiments ◽  
The Difference

A series of experiments are performed in an extensively instrumented axial flow research compressor to investigate the effects of different low reduced frequency aerodynamic forcing functions and steady loading level on the gust-generated unsteady aerodynamics of a first-stage rotor blade row. Two different two-per-rev forcing functions are considered: (1) the velocity deficit from two 90 deg circumferential inlet flow distortions, and (2) the wakes from two upstream obstructions, which are characteristic of airfoil or probe excitations. The data show that the wake-generated rotor row first harmonic response is much greater than that generated by the inlet distortion, with the difference decreasing with increased steady loading.

Unsteady Aerodynamic Interactions in a Multistage Compressor

1987 ◽  
Vol 109 (3) ◽  
pp. 420-428 ◽  
Author(s):  
V. R. Capece ◽  
S. Fleeter
Keyword(s):  
Axial Flow ◽  
Unsteady Aerodynamic ◽  
Geometric Conditions ◽  
Forcing Function ◽  
Reduced Frequency ◽  
Aerodynamic Interaction ◽  
Blade Row ◽  
Unsteady Interaction ◽  
Multistage Compressor ◽  
Series Of Experiments

The fundamental flow physics of multistage blade row interactions is experimentally investigated, with unique data obtained which quantify the unsteady harmonic aerodynamic interaction phenomena. In particular, a series of experiments is performed in a three-stage axial flow research compressor over a range of operating and geometric conditions at high reduced frequency values. The multistage unsteady interaction effects of the following on each of the three vane rows are investigated: (1) the steady vane aerodynamic loading, (2) the waveform of the aerodynamic forcing function to each vane row, including both the chordwise and traverse gust components.

Experimental Investigation of Multistage Interaction Gust Aerodynamics

1989 ◽  
Vol 111 (4) ◽  
pp. 409-417 ◽  
Author(s):  
V. R. Capece ◽  
S. Fleeter
Keyword(s):  
Axial Flow ◽  
Unsteady Aerodynamics ◽  
Unique Data ◽  
Aerodynamic Loading ◽  
Unsteady Aerodynamic ◽  
Forcing Function ◽  
Reduced Frequency ◽  
Aerodynamic Interaction ◽  
Blade Row ◽  
Potential Interactions

The fundamental flow physics of multistage blade row interactions are experimentally investigated at realistic reduced frequency values. Unique data are obtained that describe the fundamental unsteady aerodynamic interaction phenomena on the stator vanes of a three-stage axial flow research compressor. In these experiments, the effect on vane row unsteady aerodynamics of the following are investigated and quantified: (1) steady vane aerodynamic loading; (2) aerodynamic forcing function waveform, including both the chordwise and transverse gust components; (3) solidity; (4) potential interactions; and (5) isolated airfoil steady flow separation.

Rotor Blade Unsteady Aerodynamic Gust Response to Inlet Guide Vane Wakes

1993 ◽  
Vol 115 (1) ◽  
pp. 197-206 ◽  
Author(s):  
S. R. Manwaring ◽  
S. Fleeter
Keyword(s):  
Rotor Blade ◽  
Guide Vane ◽  
Axial Flow ◽  
Unsteady Aerodynamics ◽  
Rotor Blades ◽  
Inlet Guide Vane ◽  
Unsteady Aerodynamic ◽  
Forcing Function ◽  
Reduced Frequency ◽  
Flow Compressor

A series of experiments is performed in an extensively instrumented axial flow research compressor to investigate the fundamental flow physics of wake-generated periodic rotor blade row unsteady aerodynamics at realistic values of the reduced frequency. Unique unsteady data are obtained that describe the fundamental unsteady aerodynamic gust interaction phenomena on the first-stage rotor blades of a research axial flow compressor generated by the wakes from the inlet guide vanes. In these experiments, the effects of steady blade aerodynamic loading and the aerodynamic forcing function, including both the transverse and chordwise gust components, and the amplitude of the gusts, are investigated and quantified.

Rotor Blade Unsteady Aerodynamic Gust Response to Inlet Guide Vane Wakes

1991 ◽  
Author(s):  
Steven R. Manwaring ◽  
Sanford Fleeter
Keyword(s):  
Rotor Blade ◽  
Guide Vane ◽  
Axial Flow ◽  
Unsteady Aerodynamics ◽  
Rotor Blades ◽  
Inlet Guide Vane ◽  
Unsteady Aerodynamic ◽  
Forcing Function ◽  
Reduced Frequency ◽  
Flow Compressor

A series of experiments are performed in an extensively instrumented axial flow research compressor to investigate the fundamental flow physics of wake generated periodic rotor blade row unsteady aerodynamics at realistic values of the reduced frequency. Unique unsteady data are obtained which describe the fundamental unsteady aerodynamic gust interaction phenomena on the first stage rotor blades of a research axial flow compressor generated by the wakes from the Inlet Guide Vanes. In these experiments, the effects of steady blade aerodynamic loading and the aerodynamic forcing function, including both the transverse and chordwise gust components, and the amplitude of the gusts, are investigated and quantified.

Combined-Simultaneous Gust and Oscillating Compressor Blade Unsteady Aerodynamics

1999 ◽  
Author(s):  
Kuk Kim Frey ◽  
Sanford Fleeter
Keyword(s):  
Superposition Principle ◽  
Oscillation Amplitude ◽  
Unsteady Aerodynamics ◽  
Forced Response ◽  
Influence Coefficient ◽  
Torsion Mode ◽  
Unsteady Aerodynamic ◽  
Forcing Function ◽  
Blade Row ◽  
Gust Response

Experiments are performed in a 3-stage axial flow research compressor to investigate and quantify the simultaneous-combined gust and motion induced unsteady aerodynamic response of compressor 1st stage rotor blades. The gust response unsteady aerodynamics are experimentally modeled with a 2/rev forcing function. The torsion mode unsteady aerodynamics are investigated utilizing an experimental influence coefficient technique in conjunction with a unique drive system. Combined gust and oscillating unsteady aerodynamics are obtained by superposition of the separate oscillating blade row and the gust response unsteady aerodynamics. Simultaneous gust and motion induced unsteady aerodynamic response are obtained by driving the torsion mode oscillation in the presence of the 2/Rev forcing function. The effects of steady loading are quantified, with airfoil oscillation amplitude effects also studied. The combined unsteady aerodynamics establish the applicability limitations of the superposition principle at high oscillation amplitudes and high loading. In addition, the gust-blade motion phase angle is identified as a key parameter, with the accuracy of forced response prediction and the alteration of blade row stability due to gust interaction dependent on the gust-blade motion phase.

Inlet Distortion Generated Periodic Aerodynamic Rotor Response

1990 ◽  
Vol 112 (2) ◽  
pp. 298-307 ◽  
Author(s):  
S. R. Manwaring ◽  
S. Fleeter
Keyword(s):  
Rotor Blade ◽  
Amplitude Ratio ◽  
Unsteady Aerodynamics ◽  
Mean Flow ◽  
Suction Surface ◽  
Unsteady Pressure ◽  
Pressure Surface ◽  
Inlet Distortion ◽  
Loading Level ◽  
Forcing Function

Fundamental inlet distortion-generated rotor blade row unsteady aerodynamics, including the effects of both the detailed aerodynamic forcing function for the first time and steady loading are experimentally investigated in an extensively instrumented axial-flow research compressor. A two-per-rev forcing function with three gust amplitude ratios is generated. On the rotor blade pressure surface, the unsteady pressure nondimensionalization compresses the magnitude data with mean flow incidence angle. This is not the case on the higher camber suction surface. These pressure surface unsteady data are primarily affected by the steady loading level, whereas the suction surface unsteady data are a function of the steady loading level and distribution as well as the gust amplitude ratio. In addition, a design inlet distortion blade surface unsteady pressure correlation is considered.

scholarly journals Inlet Distortion Generated Periodic Aerodynamic Rotor Response

1989 ◽  
Author(s):  
Steven R. Manwaring ◽  
Sanford Fleeter
Keyword(s):  
Rotor Blade ◽  
Amplitude Ratio ◽  
Unsteady Aerodynamics ◽  
Mean Flow ◽  
Suction Surface ◽  
Unsteady Pressure ◽  
Pressure Surface ◽  
Inlet Distortion ◽  
Loading Level ◽  
Forcing Function

Fundamental inlet distortion generated rotor blade row unsteady aerodynamics, including the effects of both the detailed aerodynamic forcing function for the first time and steady loading are experimentally investigated in an extensively instrumented axial flow research compressor. A two-per-rev forcing function with three gust amplitude ratios is generated. On the rotor blade pressure surface, the unsteady pressure nondimensionalization compresses the magnitude data with mean flow incidence angle. This is not the case on the higher camber suction surface. Also, these pressure surface unsteady data are primarily affected by the steady loading level whereas the suction surface unsteady data are a function of the steady loading level and distribution as well as the gust amplitude ratio. In addition, a design inlet distortion blade surface unsteady pressure correlation is considered.

scholarly journals Wake Mixing in Axial Flow Compressors

1996 ◽  
Author(s):  
John J. Adamczyk
Keyword(s):  
Total Pressure ◽  
Axial Flow ◽  
Recovery Process ◽  
Flow Process ◽  
Direct Function ◽  
Reduced Frequency ◽  
Multi Stage ◽  
Blade Row ◽  
And Performance ◽  
Axial Flow Compressors

Over the years it has been speculated that the performance of multi-stage axial flow compressors is enhanced by the passage of a wake through a blade row prior to being mixed-out by viscous diffusion. The link between wake mixing and performance depends on the ability to recover the total pressure deficit of a wake by a reversible flow process. This paper shows that such a process exists, it is unsteady, and is associated with the kinematics of the wake vorticity field. The analysis shows that the benefits of wake total pressure recovery can be estimated from linear theory and quantified in terms of a volume integral involving the deterministic stress and the mean strain rate. In the limit of large reduced frequency the recovery process is shown to be a direct function of blade circulation. Results are presented which show that the recovery process can reduce the wake mixing loss by as much as seventy percent. Under certain circumstances this can lead to nearly a point improvement in stage efficiency, a nontrivial amount.

An Analysis System for Blade Forced Response

1993 ◽  
Vol 115 (4) ◽  
pp. 762-770 ◽  
Author(s):  
Hsiao-Wei D. Chiang ◽  
R. E. Kielb
Keyword(s):  
Unsteady Aerodynamics ◽  
Forced Response ◽  
Design Tool ◽  
Mode Shapes ◽  
Solution Technique ◽  
Campbell Diagram ◽  
Inlet Distortion ◽  
Forcing Function ◽  
Strip Theory ◽  
Analysis System

A frequent cause of turbomachinery blade failure is excessive resonant response. The most common excitation source is the nonuniform flow field generated by inlet distortion, wakes and/or pressure disturbances from adjacent blade rows. The standard method for dealing with this problem is to avoid resonant conditions using a Campbell diagram. Unfortunately, it is impossible to avoid all resonant conditions. Therefore, judgments based on past experience are used to determine the acceptability of the blade design. A new analysis system has been developed to predict blade forced response. The system provides a design tool, over and above the standard Campbell diagram approach, for predicting potential forced response problems. The incoming excitation sources are modeled using a semi-empirical rotor wake/vortex model for wake excitation, measured data for inlet distortion, and a quasi-three-dimensional Euler code for pressure disturbances. Using these aerodynamic stimuli, and the blade’s natural frequencies and mode shapes from a finite element model, the unsteady aerodynamic modal forces and the aerodynamic damping are calculated. A modal response solution is then performed. This system has been applied to current engine designs. A recent investigation involved fan blade response due to inlet distortion. An aero mechanical test had been run with two different distortion screens. The resulting distortion entering the fan was measured. With this as input data, the predicted response agreed almost exactly with the measured response. In another application, the response of the LPT blades of a counterrotating supersonic turbine was determined. In this case the blades were excited by both a wake and a shock wave. The shock response was predicted to be three times larger than that of the wake. Thus, the system identified a new forcing function mechanism for supersonic turbines. This paper provides a basic description of the system, which includes: (1) models for the wake excitation, inlet distortion, and pressure disturbance; (2) a kernel function solution technique for unsteady aerodynamics; and (3) a modal aeroelastic solution using strip theory. Also, results of the two applications are presented.

Forcing Function Measurements and Predictions of a Transonic Vaneless Counter Rotating Turbine

2000 ◽  
Author(s):  
Matthew M. Weaver ◽  
Steven R. Manwaring ◽  
Reza S. Abhari ◽  
Michael G. Dunn ◽  
Michael J. Salay ◽  
...  
Keyword(s):  
High Pressure ◽  
Three Dimensional ◽  
Unsteady Aerodynamics ◽  
Forced Response ◽  
Physical Parameters ◽  
Outer Diameter ◽  
Detailed Knowledge ◽  
Unsteady Forces ◽  
Forcing Function ◽  
Blade Row

Reducing the vibratory stress due to the forced response excitation of turbomachinery blades is an important engineering challenge facing designers. Detailed knowledge of the unsteady forces, the damping within the system, and the structural stiffness is required to predict the vibrational response and hence the high cycle fatigue life of a component. This study is focused on understanding the physical parameters influencing the unsteady forces causing the blade excitation in a transonic vaneless counter-rotating turbine, consisting of a vane row, a High Pressure (HP) spool, and a Low Pressure (LP) spool. Time averaged and time resolved measurements of the unsteady surface pressures on the HP and LP rotor blades are presented for a full scale rotating rig, using the actual engine components. Measurements were made and analyses performed at three different engine corrected aerodynamic conditions and with reduced frequencies (based on half blade chord) of approximately 10 for the unsteady aerodynamics. By varying the high-pressure rotor exit Mach number (1.44, 1.20, 1.05), the effects of varying the shock excitation to the LP blade row was studied. Extensive comparisons with CFD codes were obtained to determine flow-modeling requirements for the flow regimes studied. Comparison shows that for steady loading on the LP blade, 2D, single blade row Euler solvers are sufficient to achieve engineering accuracies. For the 1st harmonic unsteady loading, this level of modeling is adequate in the mid and lower half of the blade, but in the outer diameter region, three-dimensional effects require 3D modeling. The inclusion of nonlinear/viscous modeling shows moderately improved predictions.

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