Combined-Simultaneous Gust and Oscillating Compressor Blade Unsteady Aerodynamics

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.

Experimental Investigation of Multistage Interaction Gust Aerodynamics

10.1115/1.3262288 ◽

1989 ◽

Vol 111 (4) ◽

pp. 409-417 ◽

Cited By ~ 9

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.

Volume 4: Manufacturing Materials and Metallurgy; Ceramics; Structures and Dynamics; Controls, Diagnostics and Instrumentation; Education ◽

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

10.1115/2000-gt-0375 ◽

2000 ◽

Cited By ~ 6

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.

Application of Unsteady Aerodynamics and Aeroelasticity in Heavy-Duty Gas Turbines

Volume 4: Turbo Expo 2005 ◽

10.1115/gt2005-68813 ◽

2005 ◽

Cited By ~ 2

Author(s):

Matthew Montgomery ◽

Mehrzad Tartibi ◽

Frank Eulitz ◽

Stefan Schmitt

Keyword(s):

Gas Turbines ◽

Unsteady Aerodynamics ◽

Forced Response ◽

Operating Conditions ◽

Navier Stokes ◽

Heavy Duty ◽

Unsteady Aerodynamic ◽

Modern Computer ◽

Blade Row ◽

Unsteady Effects

Modern computer simulations can predict some aspects of the unsteady aerodynamic phenomena associated with turbomachinery blade rows. This allows analysts to investigate aeroelastic phenomena, such as flutter, and blade-row interactions, such as forced response and unsteady effects on performance. This paper describes tools and design processes used to numerically investigate unsteady aerodynamic phenomena in heavy-duty gas turbines. A linearized Navier-Stokes method from the DLR has been used to predict the aerodynamic damping of both compressor and turbine airfoils under a variety of operating conditions. Some of these predictions were validated with engine experience. Other CFD codes, including TRACE from the DLR and ITSM3D from the University of Stuttgart, have been used to predict blade-row interaction. This includes the prediction of forced response due to rotor-vane interaction and unsteady effects on performance. The effects of airfoil clocking, including the effects of cooling flow injection, have also been investigated.

5th International Symposium on Fluid Structure International, Aeroeslasticity, and Flow Induced Vibration and Noise ◽

A Harmonic Balance Approach for Modeling Three-Dimensional Nonlinear Unsteady Aerodynamics and Aeroelasticity

10.1115/imece2002-32532 ◽

2002 ◽

Cited By ~ 20

Author(s):

Jeffrey P. Thomas ◽

Earl H. Dowell ◽

Kenneth C. Hall

Keyword(s):

Limit Cycle ◽

Harmonic Balance ◽

Structural Model ◽

Oscillation Amplitude ◽

Three Dimensional ◽

Unsteady Aerodynamics ◽

Finite Amplitude ◽

Limit Cycle Oscillation ◽

Unsteady Aerodynamic ◽

Cycle Oscillation

Presented is a frequency domain harmonic balance (HB) technique for modeling nonlinear unsteady aerodynamics of three-dimensional transonic inviscid flows about wing configurations. The method can be used to model efficiently nonlinear unsteady aerodynamic forces due to finite amplitude motions of a prescribed unsteady oscillation frequency. When combined with a suitable structural model, aeroelastic (fluid-structure), analyses may be performed at a greatly reduced cost relative to time marching methods to determine the limit cycle oscillations (LCO) that may arise. As a demonstration of the method, nonlinear unsteady aerodynamic response and limit cycle oscillation trends are presented for the AGARD 445.6 wing configuration. Computational results based on the inviscid flow model indicate that the AGARD 445.6 wing configuration exhibits only mildly nonlinear unsteady aerodynamic effects for relatively large amplitude motions. Furthermore, and most likely a consequence of the observed mild nonlinear aerodynamic behavior, the aeroelastic limit cycle oscillation amplitude is predicted to increase rapidly for reduced velocities beyond the flutter boundary. This is consistent with results from other time-domain calculations. Although not a configuration that exhibits strong LCO characteristics, the AGARD 445.6 wing nonetheless serves as an excellent example for demonstrating the HB/LCO solution procedure.

Volume 5: Manufacturing Materials and Metallurgy; Ceramics; Structures and Dynamics; Controls, Diagnostics and Instrumentation; Education ◽

Forcing Function Effects on Unsteady Aerodynamic Gust Response: Part 1 — Forcing Functions

10.1115/92-gt-174 ◽

1992 ◽

Cited By ~ 2

Author(s):

Gregory H. Henderson ◽

Sanford Fleeter

Keyword(s):

Linear Theory ◽

Static Pressure ◽

Pressure Fluctuations ◽

Perforated Plate ◽

Flow Angle ◽

Unsteady Aerodynamic ◽

Forcing Function ◽

Forcing Functions ◽

Relative Flow ◽

The fundamental gust modeling assumption is investigated by means of a series of experiments performed in the Purdue Annular Cascade Research Facility. The unsteady periodic flow field is generated by rotating rows of perforated plates and airfoil cascades. In this paper, the measured unsteady flow fields are compared to linear-theory gust requirements, with the resulting unsteady gust response of a downstream stator cascade correlated with linear theory predictions in an accompanying paper. The perforated-plate forcing functions closely resemble linear-theory forcing functions, with the static pressure fluctuations small and the periodic velocity vectors parallel to the downstream mean-relative flow angle over the entire periodic cycle. In contrast, the airfoil forcing functions exhibit characteristics far from linear-theory gusts, with the alignment of the velocity vectors and the static pressure fluctuation amplitudes dependent on the rotor-loading condition, rotor solidity and the inlet mean-relative flow angle. Thus, these unique data clearly show that airfoil wakes, both compressor and turbine, are not able to be modeled with the boundary conditions of current state-of-the-art linear unsteady aerodynamic theory.

Forcing Function Effects on Unsteady Aerodynamic Gust Response: Part 1—Forcing Functions

10.1115/1.2929309 ◽

1993 ◽

Vol 115 (4) ◽

pp. 741-750 ◽

Cited By ~ 13

Author(s):

G. H. Henderson ◽

S. Fleeter

Keyword(s):

Linear Theory ◽

Static Pressure ◽

Pressure Fluctuations ◽

Perforated Plate ◽

Flow Angle ◽

Unsteady Aerodynamic ◽

Forcing Function ◽

Forcing Functions ◽

Relative Flow ◽

The fundamental gust modeling assumption is investigated by means of a series of experiments performed in the Purdue Annular Cascade Research Facility. The unsteady periodic flow field is generated by rotating rows of perforated plates and airfoil cascades. In this paper, the measured unsteady flow fields are compared to linear-theory vortical gust requirements, with the resulting unsteady gust response of a downstream stator cascade correlated with linear theory predictions in an accompanying paper. The perforated-plate forcing functions closely resemble linear-theory forcing functions, with the static pressure fluctuations small and the periodic velocity vectors parallel to the downstream mean-relative flow angle over the entire periodic cycle. In contrast, the airfoil forcing functions exhibit characteristics far from linear-theory vortical gusts, with the alignment of the velocity vectors and the static pressure fluctuation amplitudes dependent on the rotor-loading condition, rotor solidity, and the inlet mean-relative flow angle. Thus, these unique data clearly show that airfoil wakes, both compressor and turbine, are not able to be modeled with the boundary conditions of current state-of-the-art linear unsteady aerodynamic theory.

Forcing Function Effects on Unsteady Aerodynamic Gust Response: Part 2—Low Solidity Airfoil Row Response

10.1115/1.2929310 ◽

1993 ◽

Vol 115 (4) ◽

pp. 751-759 ◽

Cited By ~ 9

Author(s):

G. H. Henderson ◽

S. Fleeter

Keyword(s):

Linear Theory ◽

Perforated Plate ◽

Function Generator ◽

Pressure Transducers ◽

Response Characteristics ◽

Unsteady Aerodynamic ◽

Forcing Function ◽

Annular Cascade ◽

Airfoil Cascade ◽

The fundamental gust modeling assumption is investigated by means of a series of experiments performed in the Purdue Annular Cascade Research Facility. The unsteady periodic flow field is generated by rotating rows of perforated plates and airfoil cascades, with the resulting unsteady periodic chordwise pressure response of a downstream low-solidity stator row determined by miniature pressure transducers embedded within selected airfoils. When the forcing function exhibited the characteristics of a linear-theory vortical gust, as was the case for the perforated-plate wake generators, the resulting response on the downstream stator airfoils was in excellent agreement with the linear-theory models. In contrast, when the forcing function did not exhibit linear-theory vortical gust characteristics, i.e., for the airfoil wake generators, the resulting unsteady aerodynamic responses of the downstream stators were much more complex and correlated poorly with the linear-theory gust predictions. Thus, this investigation has quantitatively shown that the forcing function generator significantly affects the resulting gust response, with the complexity of the response characteristics increasing from the perforated-plate to the airfoil-cascade forcing functions.

Influence of Gap Detailing on Calculated Unsteady Non-Adjacent Blade Row Aero-Forcing in a Transonic Compressor Stage

10.1115/1.4048160 ◽

2020 ◽

Vol 142 (11) ◽

Author(s):

Tobias Gezork ◽

Paul Petrie-Repar

Keyword(s):

Guide Vane ◽

Computational Cost ◽

Life Time ◽

Forced Response ◽

Inlet Guide Vane ◽

Compressor Blades ◽

Transonic Compressor ◽

Forcing Function ◽

Gap Flow ◽

Blade Row

Abstract Resonant or close to resonant forced response excitation of compressor blades limits component life time and can potentially lead to high-cycle fatigue failure if the exciting forces are large and damping is insufficient. When numerically quantifying the forcing function by means of simulations, simplifications are typically made in the analysis to reduce complexity and computational cost. In this paper, we numerically investigate how the blade forcing function is influenced by the rotor tip gap flow and by flow across gaps in the upstream variable inlet guide vane row. Unsteady simulations are made using a test rig geometry where a forcing crossing with an excitation from a non-adjacent blade row had previously been measured. The effects of the gaps on the forcing function for the first torsion mode are presented for both the non-adjacent blade row excitation (changes compared with a case without gaps indicating a 20% reduction) and an adjacent excitation (changes indicating an 80% increase in terms of forcing function amplitude comparing with a case without gaps).

Rotor Blade Unsteady Aerodynamic Gust Response to Inlet Guide Vane Wakes

10.1115/1.2929207 ◽

1993 ◽

Vol 115 (1) ◽

pp. 197-206 ◽

Cited By ~ 6

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.

Unsteady Aerodynamic Interactions in a Multistage Compressor

10.1115/1.3262122 ◽

1987 ◽

Vol 109 (3) ◽

pp. 420-428 ◽

Cited By ~ 16

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.