Velocity and temperature profiles in near critical nitrogen
Boundary layer velocity and temperature profiles measured in near critical nitrogen
Graham, R. W.↗
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Bleed system design technology for supersonic inlets.
A boundary layer bleed system design procedure for supersonic inlets, with emphasis on the selection of bleed hole geometry, is described. Available experimental bleed hole performance data, coupled with bleed drag calculations, show that holes with shallow inclination are superior to holes normal to the surface in terms of overall inlet performance. Recent test results from large-scale inlet models indicate that bleed hole size, bleed hole length, and boundary layer velocity profile upstream of the bleed region are important parameters in the design of an effective and efficient bleed system.
Syberg, J.↗
Transient forced convection heat transfer from an isothermal flat plate.
An analysis is presented for laminar transient forced-convection heat transfer from a horizontal flat plate. The presented analysis results include transient velocity and temperature profiles, boundary-layer growth rate, and heat-transfer rate with time.
Nagendra, H. R.↗
Design and construction of a low-velocity boundary-layer temperature probe
This paper presents the results of a study performed to determine the probe geometry and thermal characteristics for a low-velocity boundary-layer temperature probe capable of eliminating conduction errors. Design curves for four common thermoelectric pairs are presented, and an experimental turbulent boundary-layer temperature profile is compared with the theoretical laminar sublayer equation to verify that the probe eliminates conduction errors.
Blackwell, B. F.↗
In-flight Compressible Turbulent Boundary Layer Measurements on a Hollow Cylinder at a Mach Number of 3.0
Skin temperatures, shearing forces, surface static pressures, and boundary layer pitot pressures and total temperatures were measured on a hollow cylinder 3.04 meters long and 0.437 meter in diameter mounted beneath the fuselage of the YF-12A airplane. The data were obtained at a nominal free stream Mach number of 3.0 and at wall-to-recovery temperature ratios of 0.66 to 0.91. The free stream Reynolds number had a minimal value of 4.2 million per meter. Heat transfer coefficients and skin friction coefficients were derived from skin temperature time histories and shear force measurements, respectively. Boundary layer velocity profiles were derived from pitot pressure measurements, and a Reynolds analogy factor of 1.11 was obtained from the measured heat transfer and skin friction data. The skin friction coefficients predicted by the theory of van Driest were in excellent agreement with the measurements. Theoretical heat transfer coefficients, in the form of Stanton numbers calculated by using a modified Reynolds analogy between skin friction and heat transfer, were compared with measured values. The measured velocity profiles were compared to Coles' incompressible law-of-the-wall profile.
Quinn, R. D.↗
Measurements of flow phenomena induced by suction through perforated and partially plugged surfaces
Efforts were directed towards completing construction of the windtunnel test section, assembling instrumentation, programming the data acquisition and reduction system, adjusting the streamwise pressure gradient of the test section, calibrating the hot-wire anemometer probe, and constructing and testing a smoke generator. The test section was installed in the wind tunnel and is completely operational. The streamwise pressure gradient was adjusted to be nominally zero at a free-stream velocity of 3.05 m/s (10 ft/s). This was accomplished by adjusting the upper wall of the test section to be slightly divergent. The change in static pressure between any two streamwise locations in the test section was less than one percent of the free-stream dynamic pressure. A suitable means was found for accurately calibrating the hot-wire probe which is used to measure boundary-layer velocity profiles and fluctuating velocities.
Wilkinson, S. P.↗
Experimental study of flow due to an isolated suction hole and a partially plugged suction slot
Details for construction of a model of a partially plugged, laminar flow control, suction slot and an isolated hole are presented. The experimental wind tunnel facility and instrumentation is described. Preliminary boundary layer velocity profiles (without suction model) are presented and shown to be in good agreement with the Blasius laminar profile. Recommendations for the completion of the study are made. An experimental program for study of transition on a rotating disk is described along with preliminary disturbance amplification rate data.
Goglia, G. L.↗
Computations of the Magnus effect for slender bodies in supersonic flow
A recently reported Parabolized Navier-Stokes code has been employed to compute the supersonic flow field about spinning cone, ogive-cylinder, and boattailed bodies of revolution at moderate incidence. The computations were performed for flow conditions where extensive measurements for wall pressure, boundary layer velocity profiles and Magnus force had been obtained. Comparisons between the computational results and experiment indicate excellent agreement for angles of attack up to six degrees. The comparisons for Magnus effects show that the code accurately predicts the effects of body shape and Mach number for the selected models for Mach numbers in the range of 2-4.
Sturek, W. B.↗
Hybrid suction surface for turbulent boundary layer flow
A hybrid suction surface which combines favorable aspects of both uniformly porous and discrete opening suction surfaces has been evaluated experimentally for use with incompressible turbulent boundary layers. The surface consisted of an array of closely spaced slots aligned in the direction of the freestream flow. Direct drag and mean boundary layer velocity profile measurements showed that the slotted surface had nominally the same suction characteristics as a uniformly porous surface.
Wilkinson, S. P.↗
Numerical simulation of steady supersonic flow over spinning bodies of revolution
A recently reported parabolized Navier-Stokes code has been employed to compute the supersonic flowfield about a spinning cone and spinning and nonspinning ogive cylinder and boattailed bodies of revolution at moderate incidence. The computations were performed for flow conditions where extensive measurements for wall pressure, boundary-layer velocity profiles, and Magnus force had been obtained. Comparisons between the computational results and experiment indicate excellent agreement for angles of attack up to 6 deg. At angles greater than 6 deg discrepancies are noted which are tentatively attributed to turbulence modeling errors. The comparisons for Magnus effects show that the code accurately predicts the effects of body shape for the selected models.
Sturek, W. B.↗
Calculation of a simulated 3-D high speed inlet using the Navier-Stokes equations
A hybrid numerical algorithm, developed to solve the full three-dimensional Navier-Stokes equations, is applied to the computation of the flowfield in a simulated three-dimensional high speed aircraft inlet at a Mach number of 2.5 and Reynolds number of 1.4 x 10 to the 7th based on inlet length. The numerical algorithm incorporates a coordinate transformation in order to handle general flow geometries, and utilizes the algebraic turbulent eddy viscosity model of Baldwin and Lomax. The hybrid algorithm has been vectorized on the CDC CYBER 203 computer using the SL/1 vector programming language developed at NASA Langley. The computed results are compared with experimental measurements of the ramp and cowl static pressures, and boundary layer pitot profiles. The results are also compared with a previous two-dimensional Navier-Stokes computation of the same configuration. The agreement with the experimental data is generally good; however, additional improvements in turbulence modeling are needed.
Knight, D. D.↗
Self-sustained oscillations of a shock wave interacting with a boundary layer on a supercritical airfoil
A theory is proposed of the self-sustaining oscillations of a weak shock on an airfoil in steady, transonic flow. The interaction of the shock with the boundary layer on the airfoil produces displacement thickness fluctuations which convect downstream and generate sound by interaction with the trailing edge. A feedback loop is established when this sound impinges on the shock wave, resulting in the production of further fluctuations in the displacement thickness. The details are worked out for an idealized mean boundary layer velocity profile, but strong support for the basic hypotheses of the theory is provided by a comparison with recent experiments involving the generation of acoustic "tone bursts' by a supercritical airfoil section.
Ventres, C. S.↗
Self-sustained oscillations of a shock wave interacting with a boundary layer on a supercritical airfoil
A theory is proposed of the self-sustaining oscillations of a weak shock on an airfoi in steady, transonic flow. The interaction of the shock with the boundary layer on the airfoil produces displacement thickness fluctuations which convect downstream and generate sound by interaction with the trailing edge. A feedback loop is established when this sound impinges on the shock wave, resulting in the production of further fluctuations in the displacement thickness. The details are worked out for an idealized mean boundary layer velocity profile, but strong support for the basic hypotheses of the theory is provided by a comparison with recent experiments involving the generation of acoustic 'tone bursts' by a supercritical airfoil section.
Ventres, C. S.↗
The measurement of boundary layers on a compressor blade in cascade. Volume 2: Data tables
Measurements were made of the boundary layers and wakes about a highly loaded, double-circular-arc compressor blade in cascade. These laser Doppler velocimetry measurements have yielded a very detailed and precise data base with which to test the application of viscous computational codes to turbomachinery. In order to test the computational codes at off-design conditions, the data have been acquired at a chord Reynolds number of 500,000 and at three incidence angles. Average values and 95 percent confidence bands were tabularized for the velocity, local turbulence intensity, skewness, kurtosis, and percent backflow. Tables also exist for the blade static-pressure distributions and boundary layer velocity profiles reconstructed to account for the normal pressure gradient.
Zierke, William C.↗
Relationships between topographic roughness and aeolian processes
The interaction between winds and desert surfaces has important implications for sediment transport on Earth, Mars, and Venus, and for understanding the relationships between radar backscatter and aerodynamic roughness as part of the NASA Shuttle Imaging radar (SIR-C) Mission. Here, researchers report results from measurements of boundary layer wind profiles and surface roughness at sites in Death Valley and discuss their implications. The sites included a flat to undulating gravel and sand reg, alluvial fans, and a playa. Estimates of average particle size composition of Death Valley sites and arithmetic mean values of aerodynamic roughness are given in tabular form.
Greeley, Ronald↗
An airborne study of boundary layer heat and moisture fluxes for project FIFE
A summary of work accomplished during the first International Satellite Cloud Climatology Project (ISLSCP) Field Experiment is presented. The Wyoming King Air participated in Intensive Field Campaigns (IFCs) 3 and 4 in 1987, which were committed to a combination of airborne sensible and latent heat flux measurements and soil moisture mappings, with the University of Kansas' X-band side-looking airborne radar (SLAR). A total of 9 flux missions were flown in 1987 using several different flight designs. A critical decision in the first round of aircraft flux analyses, agreed to by all the flux aircraft investigators, was to pass the aircraft data through a high-pass filter prior to the eddy-correlation flux calculations. Several conclusions were drawn from this study: (1) boundary layer (BL) profiles of heat fluxes were usually linear; (2) high-pass filtering applied to the aircraft data did not add to the disagreement between the profile; (3) undersampling at high frequencies could have accounted for as much as a 15 percent underestimate of surface fluxes; (4) disagreement between the aircraft and surface latent heat fluxes changed signs between summer and fall; (5) magnitude and sign of disagreement between aircraft and surface heat fluxes varied systematically with BL depth or height of aircraft profile; and (6) Bowen ratios from both detrended and filtered aircraft data agreed with surface values better for moist, summer cases than for dry cases.
Kelly, Robert D.↗
Experimental Investigation at a Mach Number of 2.41 of Average Skin-friction Coefficients and Velocity Profiles for Laminar and Turbulent Boundary Layers and an Assessment of Probe Effects
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O'Donnell, Robert M↗
Navier-Stokes calculations on multi-element airfoils using a chimera-based solver
A study of Navier-Stokes calculations of flows about multielement airfoils using a chimera grid approach is presented. The chimera approach utilizes structured, overlapped grids which allow great flexibility of grid arrangement and simplifies grid generation. Calculations are made for two-, three-, and four-element airfoils, and modeling of the effect of gap distance between elements is demonstrated for a two element case. Solutions are obtained using the thin-layer form of the Reynolds averaged Navier-Stokes equations with turbulence closure provided by the Baldwin-Lomax algebraic model or the Baldwin-Barth one equation model. The Baldwin-Barth turbulence model is shown to provide better agreement with experimental data and to dramatically improve convergence rates for some cases. Recently developed, improved farfield boundary conditions are incorporated into the solver for greater efficiency. Computed results show good comparison with experimental data which include aerodynamic forces, surface pressures, and boundary layer velocity profiles.
Jasper, Donald W.↗