Methods of analyzing propeller and rotor boundary layers with crossflow
Analysis of secondary flow effects in propeller and rotor boundary layers
Dwyer, H. A.↗
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Stability of Goertler vortices in boundary layers
A formal analysis of Goertler-type instability is presented. The boundary-layer and disturbance equations are formulated in a general, orthogonal, curvilinear system of coordinates constructed from the inviscid flow over a curved surface. Effects of curvature on the boundary-layer flow are analyzed. The basic approximation for the disturbance equations is presented and solved numerically. Previous analyses are discussed and compared with our analysis. It is shown that the general system of coordinates developed in this analysis and the correct order-of-magnitude analysis of the disturbance velocities with two velocity scales leads to a rational foundation for future work in Goertler vortices.
Floryan, J. M.↗
Turbulent boundary layers with secondary flow
An experimental analysis of the boundary layer on a plane wall, along which the flow occurs, whose potential flow lines are curved in plane parallel to the wall is discussed. According to the equation frequently applied to boundary layers in a plane flow, which is usually obtained by using the pulse law, a generalization is derived which is valid for boundary layers with spatial flow. The wall shear stresses were calculated with this equation.
Grushwitz, E.↗
BLAYER User Guide
Estimation of boundary layer edge or thickness is an essential aspect of utilizing high fidelity aerothermodynamic flow solutions. For viscous flow over a flat plate, the boundary layer thickness is usually defined as the distance from the wall at which the flow velocity (zero at the wall) has increased through some profile to 99% or 99.5% of the free stream velocity. In real gas flows over aerospace vehicles, a total enthalpy profile is employed for edge calculations. The importance of knowing boundary layer thickness and its relation to possible transition from laminar to turbulent flow is illustrated by Space Shuttle mission STS-114, when the appearance of tile gap filler protrusions on the nose was deemed serious enough that a crew member was called upon to exit the vehicle and remove the potential threat prior to its descent from orbit. The BLAYER utility used as part of post-processing Orion/MPCV flow solutions is a generalization of the earlier BLAYER_RESULTS utility developed following the STS-107 Columbia accident. BLAYER handles a variable number of gas species (not just 5), allows for more than one temperature and for optional extra flow quantities, and omits optional handling of Orbiter tile datasets.
momentum thicknes↗
Summary of available information on Reynolds analogy for zero-pressure-gradient, compressible, turbulent-boundary-layer flow
Mathematical analysis of Reynolds analogy for turbulent heat transfer, skin friction, and boundary layer flow in adiabatic conditions
Cary, A. M., Jr.↗
Effect of compliant wall motion on turbulent boundary layers
A critical analysis of available compliant wall data which indicated drag reduction under turbulent boundary layers is presented. Detailed structural dynamic calculations suggest that the surfaces responded in a resonant, rather than a compliant, manner. Alternate explanations are given for drag reductions observed in two classes of experiments: (1) flexible pipe flows and (2) water-backed membranes in air. Analysis indicates that the wall motion for the remaining data is typified by short wavelengths in agreement with the requirements of a possible compliant wall drag reduction mechanism recently suggested by Langley.
Bushnell, D. M.↗
Prediction of interior noise due to random acoustic or turbulent boundary layer excitation using statistical energy analysis
The feasibility of predicting interior noise due to random acoustic or turbulent boundary layer excitation was investigated in experiments in which a statistical energy analysis model (VAPEPS) was used to analyze measurements of the acceleration response and sound transmission of flat aluminum, lucite, and graphite/epoxy plates exposed to random acoustic or turbulent boundary layer excitation. The noise reduction of the plate, when backed by a shallow cavity and excited by a turbulent boundary layer, was predicted using a simplified theory based on the assumption of adiabatic compression of the fluid in the cavity. The predicted plate acceleration response was used as input in the noise reduction prediction. Reasonable agreement was found between the predictions and the measured noise reduction in the frequency range 315-1000 Hz.
Grosveld, Ferdinand W.↗
Evaluation of some control-volume techniques for analysis of shock-boundary layer interactions in supersonic inlets
Various control-volume models used to analyze the shock boundary layer bleed interaction were investigated. The bleed assumptions of the models and their influence on the analytical solutions are discussed. The results of the analysis using these models are compared with experimental boundary-layer data taken in a supersonic inlet. The experimental Mach number upstream of the interaction was 1.66, and the oblique-shock pressure ratio was 1.33. The boundary layer data included bleed flow rates up to approximately 0.6 of the upstream boundary layer mass flow rate. The first model assumed the bleed was removed from the control volume with a momentum that was characterized by a pressure intermediate between the upstream and downstream pressures. The second model assumed the control volume was bounded by a streamline dividing the bleed and residual flows and eliminated the need to specify the momentum of the bleed flow. Comparison of the results using the models showed that specifying the bleed pressure in one model was equivalent to specifying the pressure along the dividing streamline in the other.
Hingst, W. R.↗
Flight survey of the 757 wing noise field and its effects on laminar boundary layer transition. Volume 3: Extended data analysis
A flight program was completed in June of 1985 using the Boeing 757 flight research aircraft with an NLF glove installed on the right wing just outboard of the engine. The objectives of this program were to measure noise levels on the wing and to investigate the effect of engine noise on the extent of laminar flow on the glove. Details of the flight test program and results are contained in Volume 1 of this document. Tabulations and plots of the measured data are contained in Volume 2. The present volume contains the results of additional engineering analysis of the data. The latter includes analysis of the measured noise data, a comparison of predicted and measured noise data, a boundary layer stability analysis of 21 flight data cases, and an analysis of the effect of noise on boundary layer transition.
Source record↗
Neutral stability calculations for boundary-layer flows
An analysis is presented of the parallel neutral stability of three-dimensional incompressible, isothermal boundary-layer flows. A Taylor-series expansion of the dispersion relation is used to derive the general eigenvalues. These equations are functions of the complex group velocity. These relations are verified by numerical results obtained for two- and three-dimensional disturbances in two- and three-dimensional flows.
Nayfeh, A. H.↗
CFD validation of a supersonic laminar flow control concept
A three-dimensional Navier-Stokes code is used in conjunction with a linear compressible stability analysis code to develop a numerical procedure for prediction of laminar flow transition. The procedure is applied to a modified F-16XL fighter with a laminar flow control glove at supersonic speed. Details of boundary layer stability analysis indicate that, computationally, laminar flow could be realized on the highly swept wing in the absence of the leading edge attachment-line contamination. Effects of the three-dimensionality of the flow were shown to be important in the boundary layer stability analysis. The numerically predicted surface pressures compare favorably with the flight test data.
Woan, Chung-Jin↗
Analysis of pressure and heat transfer tests on surface roughness elements with laminar and turbulent boundary layers Final report
Data analysis from pressure and heat transfer tests on surface roughness elements with laminar and turbulent boundary layers
SURFACE ROUGHNESS↗
Numerical investigation of unsteady laminar incompressible co-axial boundary layer flows
Finite difference method for analysis of laminar incompressible boundary layer flows at jet exit
BOUNDARY LAYER FLOW↗
Analysis of airfoil leading edge separation bubbles
A local inviscid-viscous interaction technique was developed for the analysis of low speed airfoil leading edge transitional separation bubbles. In this analysis an inverse boundary layer finite difference analysis is solved iteratively with a Cauchy integral representation of the inviscid flow which is assumed to be a linear perturbation to a known global viscous airfoil analysis. Favorable comparisons with data indicate the overall validity of the present localized interaction approach. In addition numerical tests were performed to test the sensitivity of the computed results to the mesh size, limits on the Cauchy integral, and the location of the transition region.
Carter, J. E.↗
Analysis of airfoil leading-edge separation bubbles
A local inviscid-viscous interaction technique was developed for the analysis of low speed airfoil leading edge transitional separation bubbles. In this analysis an inverse boundary layer finite difference analysis is solved iteratively with a Cauchy integral representation of the inviscid flow which is assumed to be a linear perturbation to a known global viscous airfoil analysis. Favorable comparisons with data indicate the overall validity of the present localized interaction approach. In addition numerical tests were performed to test the sensitivity of the computed results to the mesh size, limits on the Cauchy integral, and the location of the transition region.
Vatsa, V. N.↗
Hypersonic Chemically Reacting Boundary-Layer Stability using LASTRAC
Hypersonic boundary layer transition is critical to the design of all hypersonic vehicles due to its effect on the heat transfer into the vehicle surface and potential drag enhancement or reduction during reentry. Boundary layer transition and boundary layer stability analysis under hypersonic conditions has been studied for decades, yet there is ample room for improved accuracy and further investigations into the relevant phenomena. In this work, we present a recent implementation of chemical equilibrium, finite-rate chemistry, and thermochemical nonequilibrium capabilities into LASTRAC, an existing well-established boundary-layer stability analysis code. Verification against existing numerical results in the literature are presented. LASTRAC was previously able to address calorically perfect flows. By using solutions of the Parabolized Stability Equations (PSE) with chemical and thermal nonequilibrium, we are able to investigate the effects of chemical and thermal nonequilibrium on a variety of phenomena including stationary crossflow instability on a swept wing and 2nd mode instabilities over a wedge.
Kline, H. L.↗
Validation and Uncertainty Analysis of Stereo Time-Resolved PIV Measurements for Boundary-Layer Transition Research
An uncertainty analysis was performed on the stereo time-resolved particle image velocimetry measurements that were obtained in the boundary-layer of a swept wing model. Several different approaches were undertaken to estimate the uncertainty of the PIV measurements and to understand how that uncertainty propagates through to the results of interest. It was found that the stereo registration error, which is often neglected in stereo- PIV uncertainty analysis, can cause significant errors in the measured amplitude of the stationary cross ow instability due to the large spanwise velocity gradients that occur in the ow. The self-calibrations do not always adequately correct for the stereo-registration error. A simple approach is demonstrated for estimating the error due to a misalignment of the calibration target and laser plane. This approach was found to be very successful at predicting the error in stationary cross ow amplitude caused by the misalignment. The time-resolved PIV results are also compared to previously-acquired hotwire data. The TRPIV technique is successful at measuring the same types of unsteady instabilities as the hotwire, and thus does not appear to have any adverse e ect on the transition process due to the introduction of particles into the ow. It was also found that a larger interrogation window size is beneficial for reducing the noise of the TRPIV results.
Eppink, Jenna L.↗
An investigation of a free jet at low Reynolds numbers
A comparison of the measured and calculated flow field properties of a nozzle of unusual design which was used to produce an incompressible, low Reynolds number jet is presented. The nozzle is essentially a porous metal plate which covers the end of a pipe. Results are presented for nozzle Reynolds numbers from 50 to 1000 with velocities of 100 or 200 ft/sec. The nozzle produces a uniform velocity profile at nozzle Reynolds numbers well below those at which conventional contoured nozzles are completely filled with the boundary layer. A jet mixing analysis based on the boundary layer equations accurately predicted the flow field over the entire range of Reynolds numbers tested.
Greene, G. C.↗