scholarly journals Closure to “Discussions of ‘Forcing Function Effects on Unsteady Aerodynamic Gust Response: Part 2—Low Solidity Airfoil Row Response’” (1993, ASME J. Turbomach., 115, pp. 759–761)

1993 ◽  
Vol 115 (4) ◽  
pp. 761-761
Author(s):  
G. H. Henderson ◽  
S. Fleeter
Keyword(s):  
Unsteady Aerodynamic ◽  
Forcing Function ◽  
Gust Response

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

1992 ◽  
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 ◽  
Gust Response

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

1993 ◽  
Vol 115 (4) ◽  
pp. 741-750 ◽  
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 ◽  
Gust Response

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

1993 ◽  
Vol 115 (4) ◽  
pp. 751-759 ◽  
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 ◽  
Gust Response

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.

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.

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

1992 ◽  
Author(s):  
Gregory H. Henderson ◽  
Sanford Fleeter
Keyword(s):  
Linear Theory ◽  
Perforated Plate ◽  
Function Generator ◽  
Pressure Transducers ◽  
Response Characteristics ◽  
Unsteady Aerodynamic ◽  
Forcing Function ◽  
Annular Cascade ◽  
Airfoil Cascade ◽  
Gust Response

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 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 gust characteristics, i.e., for the airfoil wake generators, the resulting unsteady aerodynamic response 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.

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.

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