scholarly journals Measured wall pressure cross spectra due to a turbulent boundary layer

1984 ◽  
Vol 76 (S1) ◽  
pp. S31-S31
Author(s):  
Nilabh Narayan ◽  
Robert Plunkett
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Wall Pressure

Decay of fluctuating wall-pressure field of Mach 5 turbulent boundary layer

AIAA Journal ◽  
1999 ◽  
Vol 37 ◽  
pp. 1088-1096
Author(s):  
O. H. Unalmis ◽  
D. S. Dolling
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Pressure Field ◽  
Wall Pressure

Predicting Turbulent Boundary Layer Wall Pressure Fluctuations in Adverse Pressure Gradients

2005 ◽  
Author(s):  
Frank J. Aldrich
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Pressure Gradient ◽  
Pressure Fluctuations ◽  
Adverse Pressure Gradient ◽  
Wall Pressure ◽  
Prediction Tool ◽  
Pressure Gradients ◽  
Wall Pressure Fluctuations ◽  
The Difference

A physics-based approach is employed and a new prediction tool is developed to predict the wavevector-frequency spectrum of the turbulent boundary layer wall pressure fluctuations for subsonic airfoils under the influence of adverse pressure gradients. The prediction tool uses an explicit relationship developed by D. M. Chase, which is based on a fit to zero pressure gradient data. The tool takes into account the boundary layer edge velocity distribution and geometry of the airfoil, including the blade chord and thickness. Comparison to experimental adverse pressure gradient data shows a need for an update to the modeling constants of the Chase model. To optimize the correlation between the predicted turbulent boundary layer wall pressure spectrum and the experimental data, an optimization code (iSIGHT) is employed. This optimization module is used to minimize the absolute value of the difference (in dB) between the predicted values and those measured across the analysis frequency range. An optimized set of modeling constants is derived that provides reasonable agreement with the measurements.

Turbulent Wall-Pressure Fluctuations: A New Model for Off-Axis Cross-Spectral Density

1997 ◽  
Vol 119 (2) ◽  
pp. 277-280 ◽  
Author(s):  
B. A. Singer
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Spectral Density ◽  
Flow Direction ◽  
Wall Pressure ◽  
Mean Flow ◽  
New Approach ◽  
Cross Spectral Density ◽  
The Mean ◽  
The Cross

Models for the distribution of the wall-pressure under a turbulent boundary layer often estimate the coherence of the cross-spectral density in terms of a product of two coherence functions. One such function describes the coherence as a function of separation distance in the mean-flow direction, the other function describes the coherence in the cross-stream direction. Analysis of data from a large-eddy simulation of a turbulent boundary layer reveals that this approximation dramatically underpredicts the coherence for separation directions that are neither aligned with nor perpendicular to the mean-flow direction. These models fail even when the coherence functions in the directions parallel and perpendicular to the mean flow are known exactly. A new approach for combining the parallel and perpendicular coherence functions is presented. The new approach results in vastly improved approximations for the coherence.

Wavenumber Spectra of High Magnitude Wall Pressure Events in a Numerically Simulated Turbulent Boundary Layer

1997 ◽  
Vol 119 (2) ◽  
pp. 281-288
Author(s):  
B. M. Abraham ◽  
W. L. Keith
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Fourier Transforms ◽  
Experimental Studies ◽  
Detection Algorithm ◽  
Wall Pressure ◽  
Negative Events ◽  
Discrete Fourier Transforms ◽  
High Magnitude ◽  
The Time Domain

A method for conditionally sampling the spatial field of the wall pressure beneath a turbulent boundary layer in order to search for high magnitude events and calculate the corresponding wavenumber spectrum is presented. The high magnitude events are found using a simple peak detection algorithm at a fixed instant in time and the wavenumber spectra are calculated using discrete Fourier transforms. The frequency of occurrence for high magnitude positive events is found to be approximately the same as for high magnitude negative events. The contribution of the high magnitude events to the rms wall pressure for various trigger levels is calculated and compared with results from similar experimental studies performed in the time domain. The high magnitude events are shown to occur infrequently and to contribute significantly to the rms wall pressure. Wavenumber spectra from the high magnitude positive and negative events are calculated and compared with the unconditionally sampled spectra. The high magnitude events contain energy focused around a particular stream-wise wavenumber and have high broadband spectral levels.

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