Author: Carolyn Ceder KarangelenPublisher:
ISBN:
Category : Fluid dynamics
Languages : en
Pages : 420
Book Description
Temporal and Spectral Features of Wall Pressure Fluctuations Beneath a Turbulent Boundary Layer
Author: Carolyn Ceder KarangelenPublisher:
ISBN:
Category : Fluid dynamics
Languages : en
Pages : 420
Book Description
The Wave Number Frequency Spectrum of the Wall Pressure Fluctuations Beneath a Turbulent Boundary Layer
Author: Eric ManohaWall-pressure Fluctuations and Pressure-velocity Correlations in a Turbulent Boundary Layer
Author: John S. SerafiniPublisher:
ISBN:
Category : Fluid dynamics
Languages : en
Pages : 88
Book Description
This experimental study was carried out at a free-stream Mach number of 0.6 and a Reynolds number per foot of 3.45 x 106. The magnitudes of the wall-pressure fluctuations agree with the Lilley-Hodgson theoretical results. Space-time correlations of the wall-pressure fluctuations generally agree with Willmarth's results for longitudinal separation distances. The convection velocity of the fluctuations is found to increase with increasing separation distances, and its significance is explained. Measurements with the longitudinal component of the velocity fluctuations indicate that the contributions to the wall-pressure fluctuations are from two regions, an inner region near the wall and an outer region linked with the intermittency.
Scientific and Technical Aerospace Reports
Author: Wall Pressure Fluctuations Beneath an Axially Symmetric Turbulent Boundary Layer on a Cylinder
Author: Chi-Sheng YangPublisher:
ISBN:
Category : Turbulence
Languages : en
Pages : 101
Book Description
Measurements of the turbulent pressure field on the outer surface of a 3 inch diameter cylinder were made at a point 24 feet downstream of the origin of the turbulent boundary layer. The root-mean square wall pressure was 2.42 times the wall shear stress. The normalized power spectrum at high frequencies contained twice the energy density of the spectrum beneath a plane boundary layer. The convection speed was the same as that in a plane boundary layer but the eddy size was smaller by a factor of two. The smaller eddy size and unchanged convection speed account for the greater energy in the spectrum at high frequencies. (Author).
Some Features of Surface Pressure Fluctuations in Turbulent Boundary Layers with Zero and Favorable Pressure Gradients
Author: Brian E. McGrathPublisher:
ISBN:
Category : Boundary layer noise
Languages : en
Pages : 138
Book Description
Low-Wavenumber Wall Pressure Fluctuations Due to Boundary-Layer Transition
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
Boundary layer transition is an important contributor to sensor flow-induced self noise. The pressure fluctuations caused by this spatially bounded and intermittent, phenomenon encompass a very wide range of spatial wave numbers and temporal frequencies. Here, we analyze the wavevector-frequency spectrum of the wall pressure fluctuations due to subsonic boundary-layer transition as it occurs on a flat plate under zero pressure gradient conditions. Based on previous measurements of the statistic of the boundary-layer intermittence it is found that transition induces higher low-streamwise wave number wall pressure level than does a fully-developed turbulent boundary layer (TBL) that might superficially exist at the same location and at the same Reynolds number. The transition zone spanwise wavenunmber pressure components are virtually unchanged from the TBL ease. The results suggest that transition may be more effective than the TBL in forcing structural excitation at low Mach numbers and it may have a more intense radiated noise contribution on a per unit area basis. This may help explain increases in measured sensor self noise when the sensors are placed near the transition zone.
Pressure Fluctuations in Turbulent Boundary Layers
Author: M. V. LowsonPublisher:
ISBN:
Category : Atmospheric pressure
Languages : en
Pages : 36
Book Description
Turbulent Wall-Pressure Fluctuations: New Model for Off-Axis Cross-Spectral Density
Author: Properties of the Fluctuating Wall Pressure Field of a Turbulent Boundary Layer
Author: M. K. BullPublisher:
ISBN:
Category : Turbulent boundary layer
Languages : en
Pages : 34
Book Description
The results of measurements of various statistical properties of the fluctuating wall-pressure field associated with turbulent subsonic boundary layer flow in conditions covering a range of values of boundary layer thickness and flow speed are given. The measured quantities include overall rms pressures, frequency spectra, and longitudinal and lateral space-time correlations in both broad and narrow frequency bands. Some experimental values of space-time correlation between wall-pressure fluctuations and turbulent velocity fluctautions at various positions in the boundary layer are also presented. These experimental results and some of their implications on the structure of the wallpressure field and the nature of its convection and decay are discussed. (Author).