scholarly journals Unsteady Aerodynamic Forcing Functions: A Comparison Between Linear Theory and Experiment

1993 ◽  
Author(s):  
John M. Feiereisen ◽  
Matthew D. Montgomery ◽  
Sanford Fleeter
Keyword(s):  
Linear Theory ◽  
Static Pressure ◽  
Perforated Plate ◽  
Velocity Data ◽  
Pressure Data ◽  
Perforated Plates ◽  
Unsteady Aerodynamic ◽  
Split Flow ◽  
Potential Component ◽  
Pressure Perturbations

The unsteady flow field generated by rotating rows of perforated plates and airfoil cascades are mathematically split into vortical and potential components using two methods, one relying entirely on velocity data and the other utilizing both velocity and unsteady static pressure data. The propagation and decay of these split flow perturbations are then examined and compared to linear theory predictions. The perforated plate gusts closely resemble linear theory vortical gusts. Both splitting methods indicate that they are dominantly vortical gusts with insignificant unsteady static pressure perturbations. The airfoil gusts resemble linear theory combined vortical and potential gusts. The recombined airfoil gusts using the vortical and potential components calculated by the method using only unsteady velocity data do not necessarily resemble the measured gusts, nor do they behave axially as predicted by linear theory. The recombined airfoil gusts using the linear theory components calculated by the method using both unsteady velocity and unsteady static pressure data do resemble the measured gusts and behave axially as predicted by linear theory, with the vortical component propagating unattenuated and the potential component decaying at the rate predicted by linear theory.

Unsteady Aerodynamic Forcing Functions: A Comparison Between Linear Theory and Experiment

1994 ◽  
Vol 116 (4) ◽  
pp. 676-685 ◽  
Author(s):  
J. M. Feiereisen ◽  
M. D. Montgomery ◽  
S. Fleeter
Keyword(s):  
Linear Theory ◽  
Static Pressure ◽  
Perforated Plate ◽  
Velocity Data ◽  
Pressure Data ◽  
Perforated Plates ◽  
Unsteady Aerodynamic ◽  
Split Flow ◽  
Potential Component ◽  
Pressure Perturbations

The unsteady flow field generated by rotating rows of perforated plates and airfoil cascades is mathematically split into vortical and potential components using two methods, one relying entirely on velocity data and the other utilizing both velocity and unsteady static pressure data. The propagation and decay of these split flow perturbations are then examined and compared to linear theory predictions. The perforated plate gusts closely resemble linear theory vortical gusts. Both splitting methods indicate that they are dominantly vortical gusts with insignificant unsteady static pressure perturbations. The airfoil gusts resemble linear theory combined vortical and potential gusts. The recombined airfoil gusts using the vortical and potential components calculated by the method using only unsteady velocity data do not necessarily resemble the measured gusts, nor do they behave axially as predicted by linear theory. The recombined airfoil gusts using the linear theory components calculated by the method using both unsteady velocity and unsteady static pressure data do resemble the measured gusts and behave axially as predicted by linear theory, with the vortical component propagating unattenuated and the potential component decaying at the rate predicted by linear theory.

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.

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.

High Speed Flow through Perforated Plates

1960 ◽  
Vol 64 (590) ◽  
pp. 103-105
Author(s):  
P. G. Morgan
Keyword(s):  
Pressure Drop ◽  
High Speed ◽  
Perforated Plate ◽  
Wire Mesh ◽  
Flow Conditions ◽  
High Speed Flow ◽  
Perforated Plates ◽  
Speed Flow ◽  
Flow Through ◽  
Points Of View

The flow through porous screens has been widely studied from both the theoretical and experimental points of view. The most widely used types of screen are the wire mesh and the perforated plate, and the majority of the literature has been concerned with the former. Several attempts have been made to correlate the parameters governing the flow through such screens, i.e. the pressure drop, the flow conditions and the geometry of the mesh.

scholarly journals THE STUDY OF ACOUSTIC CHARACTERISTICS OF THE PERFORATED AND HOMOGENOUS PLATES WITH SIMILAR GEOMETRICAL DIMENSIONS

Akustika ◽  
2019 ◽  
Vol 32 ◽  
pp. 79-82
Author(s):  
Valery Kirpichnikov ◽  
Lyudmila Drozdova ◽  
Alexei Koscheev ◽  
Ernst Myshinsky
Keyword(s):  
Resonant Frequency ◽  
Acoustic Radiation ◽  
Perforated Plate ◽  
Acoustic Characteristics ◽  
Resonant Frequencies ◽  
Perforated Plates ◽  
Resonance Frequencies ◽  
Flexural Vibrations ◽  
Geometrical Dimensions

The resonance frequencies of the flexural vibrations, input vibration excitability and acoustic radiation of the homogeneous and perforated plates were investigated. It is established that the average reduction range of the lower resonant frequency of flexural vibrations of the tested plates with the holes virtually coincides with the predictive estimate. The levels of the input vibration excitability of the perforated plate at the lower resonant frequencies exceeded the levels at the corresponding frequencies of the homogeneous plates greater than the calculated value. The levels of resonance acoustic radiation of the perforated plate were significantly less than of the homogeneous one.

The Aerodynamic Drag of Perforated Plates at Zero Incidence

1958 ◽  
Vol 62 (568) ◽  
pp. 301-303 ◽  
Author(s):  
P. Minton ◽  
J. R. D. Francis
Keyword(s):  
Pipe Flow ◽  
Aerodynamic Drag ◽  
Perforated Plate ◽  
Perforated Plates ◽  
Drag Forces ◽  
Flow Experiments

Perforated Plates have been used at large angles of incidence to produce drag forces and evidence on their properties has been published by de Bray. Less appears to be known about the drag forces on such surfaces at zero incidence, although they are usually considered to be aerodynamically rough. This has been confirmed by Ambrose, who carried out pipe flow experiments using perforated liners which fitted tightly in the bore of a pipe. Perforated plates used in this way do not allow flow completely through them and give “pitted” surfaces. If a perforated plate is mounted so that it is possible for cross flows to occur between the main flows on both sides of the plate the drag forces on it may be affected, and in this case the perforations will be referred to as “holes.”

Vibration Characteristics of a Perforated Plate Immersed in Fluid

2012 ◽  
Author(s):  
Tomohiro Ito ◽  
Atsuhiko Shintani ◽  
Chihiro Nakagawa
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Damping Ratio ◽  
Thermal Power ◽  
Perforated Plate ◽  
Vibration Characteristics ◽  
Chemical Plants ◽  
Perforated Plates ◽  
Stiffness Reduction ◽  
Test Models

Perforated plates are used in many mechanical structures in thermal power plants, nuclear power plants, or chemical plants etc. Cylindrical structures made by the perforated plates are also found in many places. However, vibration characteristics of the structures made by perforated plates are not fully clarified, especially for the structures immersed in liquid. The stiffness of the structures becomes smaller than that of ones made by simple plates with no holes, while the mass of the structures also becomes smaller. According to the balance between the stiffness reduction and mass reduction, natural frequencies will be decided. Moreover, added mass and added damping effects are very large in liquid, and are thought to largely change due to holes. In this study, as a fundamental step, a perforated plate is treated. The vibration characteristics such as natural frequency and damping ratio are studied for various hole numbers or various opening ratios by both numerical simulations and simple test models. Vibration tests are conducted in liquid as well as in air.

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