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Skin friction and velocity profile family for compressible turbulent boundary layers
The paper presents a general approach to constructing mean velocity profiles for compressible turbulent boundary layers with isothermal or adiabatic walls. The theory is based on a density-weighted transformation that allows the extension of the incompressible similarity laws of the wall to the compressible regions. The velocity profile family is compared to a range of experimental data, and excellent agreement is obtained. A self-consistent skin friction law, which satisfies the proposed velocity profile family, is derived and compared with the well-known Van Driest II theory for boundary layers in zero pressure gradient. The results are found to be at least as good as those obtained by using the Van Driest II transformation.
A modified wall wake velocity profile for turbulent compressible boundary layers.
The law of the wake and the law of the wall in incompressible turbulent boundary layers formulated by Coles (1956) and their use by Mathews et al. (1970) in the development of a wall-wake representation of the velocity profile in a form applicable for isoenergetic compressible boundary layers are extended to a modified wall-wake velocity profile for turbulent compressible boundary layers. The modified wall-wake profile is shown to provide good representations of experimental velocity distributions.
A class of momentum integral methods for turbulent boundary layers based on the family of equilibrium profiles
Momentum integral method for turbulent boundary layers based on equilibrium profiles family, considering weighting function specification techniques
A wall-wake velocity profile for turbulent compressible boundary layers with heat transfer
A modified form of the wall-wake profile which is applicable to flows with heat transfer is presented. The modified profile takes into account the effect of a turbulent Prandtl number; it was found to provide a good representation of the experimental data from several sources. The C sub f values which are determined by a least squares fit of the profile to the data agree well with values which were measured by the floating element technique.
Data communications and monitor for the Penn State University profiler network
The profiler network installed by the Department of Meteorology at Penn State University utilizes a microcomputer for network monitoring and control. The network consists of two VHF and one UHF wind profiling Doppler radars. Additional measurement systems added to the network include temperature and humidity profiling radiometers, sodar for boundary layer wind profiling and selected surface based baseline systems. Remote diagnostic capabilities were also implemented in the Penn State network. It is possible to remotely analyze many specific malfunctions of the transmitter or signal processor.
Intrepretation of surface features and surface processes on Mars
Eolian erosion and deposition on earth was studied in order to interpret the eolian land forms of Mars. Emphasis of the wind tunnel studies was on the flow field around models of eolian forms. Areas of the wind tunnel studies include: simulation of the atmospheric boundary layer; velocity profile measurements around different models in the desert boundary layer, and estimating shear stress distributions on the model surfaces; flow visualization techniques; streamline mapping using tuft photographs; and roughness contrasts.
Comparison of Profile-drag and Boundary-layer Measurements Obtained in Flight and in the Full-scale Wind Tunnel
The effect of the existing turbulence in the full scale tunnel was determined from measurements of the profile drag of an N-22 section by the momentum method under corresponding conditions in flight and the tunnel. The transition-point location on the upper surface of the air-foil was also determined from velocity surveys in the boundary layer. The measurements were made at section lift coefficients from 0.480 to 0.635 with a range of Reynolds Numbers from 4,600,000 to 3,900,000. The results show that the end of transition occurs at approximately the same point on the airfoil in flight and in the tunnel. The transition region was somewhat broader in the tunnel and started farther forward than in flight. The laminar profiles in the tunnel had some characteristics of transition profiles in the tunnel and had a much steeper slope near the surface than did the laminar profiles obtained in flight. These differences, however, caused an increase of only 0.0001 in the profile-drag coefficients, as determined by the momentum method.
Further solutions of the Falkner-Skan equation.
Solutions to Falkner-Skan equation, making similarity solutions for pressure gradient parameter physically acceptable
Relationship between temperature and velocity profiles in a turbulent boundary layer along a supersonic nozzle with heat transfer
Turbulent boundary layer air flow through supersonic convergent-divergent nozzle with heat transfer, considering relationship between temperature and velocity profiles
Power-law velocity-profile-exponent variations with Reynolds number, wall cooling, and Mach number in a turbulent boundary layer
Turbulent boundary layer velocity profiles with favorable pressure gradients
Calculation of compressible adverse pressure gradient turbulent boundary layers.
Difficulties encountered in computing profile shapes in supersonic turbulent boundary layers with large pressure gradients, which result from a disagreement between data and theory, are investigated. Possible reasons given by various authors for this disagreement are discussed. Initial results seem to indicate that conventional reasons do not account for the observed difficulties. However, inclusion of the effect of curvature upon turbulent mixing has brought an improvement in calculations. Possible three-dimensional effects are also examined.
Boundary-layer measurements in accelerated flows near Mach 1
Velocity and temperature profile measurements for adiabatic boundary layers on cylindrical bodies in transonic parallel accelerated flows
Calculations of Laminar Heat Transfer Around Cylinders of Arbitrary Cross Section and Transpiration-Cooled Walls with Application to Turbine Blade Cooling
An approximate method for the development of flow and thermal boundary layers in the laminar region on cylinders with arbitrary cross section and transpiration-cooled walls is obtained by the use of Karman's integrated momentum equation and an analogous heat-flow equation. Incompressible flow with constant property values throughout the boundary layer is assumed. The velocity and temperature profiles within the boundary layer are approximated by expressions composed of trigonometric functions. Shape parameters for these profiles and functions necessary for the solution of the boundary-layer equations are presented as graphs so that the calculation for any specific case is reduced to the solution of two first-order differential equations. This method is applied to determine local heat-transfer coefficients and surface temperatures in the laminar flow region of the transpiration-cooled turbine blades for a given coolant flow rate, or to calculate the coolant flow distribution which is necessary in order to keep the blade temperature uniform along the surface.
Three Dimensional Compressible Turbulent Flow Computations for a Diffusing S-Duct With/Without Vortex Generators
Numerical investigations on a diffusing S-duct with/without vortex generators and a straight duct with vortex generators are presented. The investigation consists of solving the full three-dimensional unsteady compressible mass averaged Navier-Stokes equations. An implicit finite volume lower-upper time marching code (RPLUS3D) has been employed and modified. A three-dimensional Baldwin-Lomax turbulence model has been modified in conjunction with the flow physics. A model for the analysis of vortex generators in a fully viscous subsonic internal flow is evaluated. A vortical structure for modeling the shed vortex is used as a source term in the computation domain. The injected vortex paths in the straight duct are compared with the analysis by two kinds of prediction models. The flow structure by the vortex generators are investigated along the duct. Computed results of the flow in a circular diffusing S-duct provide an understanding of the flow structure within a typical engine inlet system. These are compared with the experimental wall static-pressure, static- and total-pressure field, and secondary velocity profiles. Additionally, boundary layer thickness, skin friction values, and velocity profiles in wall coordinates are presented. In order to investigate the effect of vortex generators, various vortex strengths are examined in this study. The total-pressure recovery and distortion coefficients are obtained at the exit of the S-duct. The numerical results clearly depict the interaction between the low velocity flow by the flow separation and the injected vortices.
Mean horizontal wind profiles measured in the atmospheric boundary layer about a simulated block building
Instrumented wind towers are used to measure the three components of wind about a simulated block building. The mean horizontal wind profiles over the building are compared with wind profiles measured in the absence of the building and the wind speed deficit in the wake of the building is correlated. The turbulence intensity is of the order of 20% in the undisturbed flow whereas the free stream turbulence intensity of wind-tunnel studies is generally not more than 5%. The velocity profiles measured in the undisturbed flow zones support the representation of a neutrally stable atmospheric boundary layer with a logarithmic wind profile.