Part V: Steady and oscillatory aerofoil-spoiler-flap characteristics

1987 ◽  
Vol 91 (910) ◽  
pp. 479-492 ◽  
Author(s):  
H. B. Tou ◽  
G. J. Hancock
Keyword(s):  
Experimental Data ◽  
Small Amplitude ◽  
Separated Flow ◽  
Separation Point ◽  
Two Dimensional ◽  
Harmonic Motion ◽  
Simple Harmonic Motion ◽  
Attached Flow ◽  
Flow Through ◽  
Low Speeds

Summary An inviscid model for a steady two-dimensional aerofoil-spoiler at low speeds is applied to an aerofoil-spoiler-plain flap configuration. The model is extended to an aerofoil-spoiler-slotted flap configuration. The flow through a slotted flap can result in either attached flow or separated flow about the flap. The location of the separation point on the flap has to be assumed, it is taken empirically to fit experimental data. The inviscid model is extended to the aerofoil-spoiler-slotted flap configuration with the spoiler oscillating in small amplitude simple harmonic motion about a mean spoiler angle. Although both the steady and unsteady models for the aerofoil-spoiler-flap configuration are crude, the results look encouraging.

Part II: Steady aerofoil-spoiler characteristics

1987 ◽  
Vol 91 (908) ◽  
pp. 359-366
Keyword(s):  
Separated Flow ◽  
Experimental Results ◽  
Surface Singularity ◽  
Separation Region ◽  
Two Dimensional ◽  
Trailing Edge ◽  
Singularity Method ◽  
Total Head ◽  
Low Speeds ◽  
Theoretical Results

Summary A surface singularity method has been formulated to predict two-dimensional spoiler characteristics at low speeds. Vorticity singularities are placed on the aerofoil surface, on the spoiler surface, on the upper separation streamline from the spoiler tip and on the lower separation streamline from the aerofoil trailing edge. The separation region is closed downstream by two discrete vortices. The flow inside the separation region is assumed to have uniform total head. The downstream extent of the separated wake is an empirical input. The flows both external and internal to the separated regions are solved. Theoretical results have been obtained for a range of spoiler-aerofoil configurations which compare reasonably with experimental results. The model is deficient in that it predicts a higher compression ahead of the spoiler than obtained in practice. Furthermore, there is a minimum spoiler angle below which a solution is not possible; it is thought that this feature is related to the physical observation that at small spoiler angles, the separated flow from the spoiler reattaches on the aerofoil upper surface ahead of the trailing edge.

A REGENERATIVE COOLING SYSTEM FOR THE CHAMBER OF A LIQUID-PROPELLANT ROCKET ENGINE WITH INTERCHANNEL COOLANT FLOW THROUGH A METAL MESH

2021 ◽  
pp. 65-77
Author(s):  
Fedor V. PELEVIN ◽  
Aleksey V. PONOMAREV
Keyword(s):  
Experimental Data ◽  
Heat Exchange ◽  
Porous Metal ◽  
Coolant Flow ◽  
Two Dimensional ◽  
Liquid Propellant ◽  
Metal Mesh ◽  
Regenerative Cooling ◽  
Flow Through ◽  
Propellant Rocket

The paper discusses a new method for regenerative cooling of the chamber of liquid-propellant rocket engines using the concept of interchannel coolant flow through a porous metal mesh made by vacuum diffusion welding of woven metal netting. It provides a theoretical rationale for switching from unidimensional (longitudinally channeled) flow to two-dimensional (interchannel) inter-mesh flow coolant through a porous mesh. It provides experimental data for hydraulic resistance and heat exchange in porous metal meshes. Based on the experimental data, a generalized criterial equation was obtained for surface heat release in the paths with interchannel two-dimensional intermesh coolant flow through metal mesh. The paper examines the efficiency of heat exchange in the paths with interchannel coolant flow. Key words: regenerative cooling, interchannel flow; vacuum diffusion technology, metal mesh; hydraulic resistance; heat exchange, heat exchange efficiency.

Generalization of Experimental Data for Compressor Cascades at Low Speeds

1970 ◽  
Author(s):  
V. S. Beknev
Keyword(s):  
Experimental Data ◽  
Pressure Distribution ◽  
Loss Coefficient ◽  
Two Dimensional ◽  
Minimum Loss ◽  
Maximum Value ◽  
Isentropic Exponent ◽  
Loss Coefficients ◽  
Low Speeds ◽  
Drag Ratio

The author compares three different approaches for generalization of experimental data for two-dimensional compressor cascades at low speeds: generalization for maximum value of lift-drag ratio, generalization for maximum cascade quality, and generalization for minimum loss coefficient. Some results given, of comparison for incidence and deviation angles, solidities, and loss coefficients, show the largest difference to be for incidence angles and loss coefficients. Influence of isentropic exponent on the airfoil pressure distribution and cascade losses is considered.

Heat transfer from turbulent separated flows

1967 ◽  
Vol 27 (1) ◽  
pp. 97-109 ◽  
Author(s):  
D. B. Spalding
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Reynolds Number ◽  
Separated Flow ◽  
Separated Flows ◽  
Two Dimensional ◽  
Hydrodynamic Properties ◽  
One Dimensional ◽  
Actual Mechanism ◽  
Turbulent Separated Flow

A power-law relation is derived between the Stanton number and the Reynolds number, expressing the law of heat transfer for a wall adjacent to a region of turbulent separated flow. The derivation is based on Prandtl's (1945) proposal for the laws of dissipation, diffusion and generation of turbulent kinetic energy. The constants appearing in these laws are determined by reference to experimental data for the hydrodynamic properties of the constant-stress and the linear-stress layers.The agreement between the resulting predictions and the experimental data of other workers is sufficiently good to suggest that the actual mechanism of heat transfer from separated flows has much in common with that which is postulated. Closer agreement can be expected only after the present one-dimensional analysis has been superseded by a two-dimensional one.

Annular Compressible Squeeze Films

1985 ◽  
Vol 107 (4) ◽  
pp. 544-547 ◽  
Author(s):  
J. J. Blech
Keyword(s):  
Exact Solution ◽  
Small Amplitude ◽  
Outer Radius ◽  
Radius Ratio ◽  
Harmonic Motion ◽  
Cutoff Frequencies ◽  
Simple Harmonic Motion ◽  
Pressure Distributions

The exact solution for annular isothermal squeeze films in either parallel or tilting simple harmonic motion of small amplitude is derived. Pressure distributions, forces and moments are given for any inner to outer radius ratio. Comparison of cutoff frequencies with approximate values of previous works indicates that for low inter to outer radius, there exist deviations between the approximate frequencies to the present values. Damping forces correlate well with Green and Etsion’s work for low squeeze numbers and moderately large inner to outer radius ratios.

scholarly journals Mixing in Axial-Flow Compressors: Conclusions Drawn From 3-D Navier-Stokes Analyses and Experiments

1990 ◽  
Author(s):  
J. H. Leylek ◽  
D. C. Wisler
Keyword(s):  
Experimental Data ◽  
Numerical Solutions ◽  
Turbulence Modeling ◽  
Axial Flow ◽  
Separated Flow ◽  
Navier Stokes ◽  
Tracer Gas ◽  
Flow Through ◽  
First Time ◽  
Axial Flow Compressors

Extensive numerical analyses and experiments have been conducted to understand mixing phenomena in multistage, axial-flow compressors. For the first time in the literature the following are documented: detailed 3-D Navier-Stokes solutions, with high-order turbulence modeling, are presented for flow through a compressor vane row at both design and off-design (increased) loading; comparison of these computations with detailed experimental data show excellent agreement at both loading levels; the results are then used to explain important aspects of mixing in compressors. The 3-D analyses show the development of spanwise and cross-passage flows in the stator and the change in location and extent of separated flow regions as loading increases. The numerical solutions support previous interpretations of experimental data obtained on the same blading using the ethylene tracer-gas technique and hot-wire anemometry. These results, plus new tracer-gas data, show that both secondary flow and turbulent diffusion are mechanisms responsible for both spanwise and cross-passage mixing in axial-flow compressors. The relative importance of the two mechanisms depends upon the configuration and loading levels. It appears that using the correct spanwise distributions of time-averaged inlet boundary conditions for 3-D Navier-Stokes computations enables one to explain much of the flow physics for this stator.

scholarly journals Flow Past a Flat Plate With a Vortex/Sink Combination

1996 ◽  
Vol 63 (2) ◽  
pp. 543-550 ◽  
Author(s):  
N. J. Mourtos ◽  
M. Brooks
Keyword(s):  
Flat Plate ◽  
Current Model ◽  
Angle Of Attack ◽  
Separated Flow ◽  
Leading Edge ◽  
Classical Solutions ◽  
Two Dimensional ◽  
Trailing Edge ◽  
Kutta Condition ◽  
Attached Flow

This paper presents a potential flow model for the leading edge vortex over a two-dimensional flat plate at an angle of attack. The paper is an extension of a model by Saffman and Sheffield (1977). A sink has been added in this model in an effort to satisfy the Kutta condition at both the leading edge and the trailing edge of the plate. The introduction of the sink was inspired by the fact that most steady vortices in nature appear in combination with a flow feature which can be interpreted as a sink at their cores when the flow is analyzed in a two-dimensional observation plane. As in the Saffman and Sheffield model, the presence of a vortex results in increased lift; however, in the current model a unique vortex/sink position is found at each angle of attack. A comparison has also been made between the lift and the drag of this model and the corresponding results for two classical solutions of flow over a flat plate: (a) the fully attached flow with the Kutta condition satisfied at the trailing edge only and (b) the Helmholtz solution of fully separated flow.

Modelling Injector Flow Including Cavitation Effects for Diesel Applications

2007 ◽  
Author(s):  
F. Peng Ka¨rrholm ◽  
Henry Weller ◽  
Niklas Nordin
Keyword(s):  
Experimental Data ◽  
Equation Of State ◽  
Compressible Liquid ◽  
Physical Parameters ◽  
Two Dimensional ◽  
Pressure Profiles ◽  
Barotropic Equation ◽  
Flow Through ◽  
Mass Flows ◽  
Model Diesel

In this paper, cavitation and pressure parameters measured in a model diesel injector are compared to data acquired by numerical simulations using a new code developed for the Open-FOAM platform, which uses a barotropic equation of state together with the homogeneous equilibrium assumption. It is a viscid code, allowing both compressible liquid and vapour to be modelled. The mass flow and cavitation probabilities obtained from the simulations are compared to data obtained in experiments performed at AVL’s laboratories, in which the flow through an almost two-dimensional nozzle was examined. The experimental data used include pressure profiles and cavitation images. The model proved to be able to predict cavitation probabilities, mass flows, and the occurrence of super-cavitation in the channel. In addition, it proved to be stable in its dependency on physical parameters, and grid independent.

Numerical Solution of Inviscid Two-Dimensional Transonic Flow Through a Cascade

1987 ◽  
Vol 109 (1) ◽  
pp. 108-113
Author(s):  
J. Forˇt ◽  
K. Kozel
Keyword(s):  
Experimental Data ◽  
Weak Solution ◽  
Numerical Solution ◽  
Transonic Flow ◽  
Numerical Procedure ◽  
Numerical Results ◽  
Two Dimensional ◽  
System Of Difference Equations ◽  
Flow Through ◽  
Turbine Cascades

The paper presents a method of numerical solution of transonic potential flow through plane cascades with subsonic inlet flow. The problem is formulated as a weak solution with combined Dirichlet’s and Neumann’s boundary conditions. The numerical procedure uses Jameson’s rotated difference scheme and the SLOR technique to solve a system of difference equations. Numerical results of transonic flow are compared with experimental data and with other numerical results for both compressor and turbine cascades near choke conditions.

A computational method for the flow through non-uniform gauzes: the general two-dimensional case

1969 ◽  
Vol 36 (2) ◽  
pp. 367-383 ◽  
Author(s):  
J. T. Turner
Keyword(s):  
Experimental Data ◽  
Computational Method ◽  
Dimensional Case ◽  
Two Dimensional ◽  
Numerical Techniques ◽  
Dimensional Flow ◽  
Two Dimensional Flow ◽  
Linearized Theory ◽  
Flow Through ◽  
Comparison With Experimental Data

A computational method is presented for the analysis of two-dimensional flow through a non-uniform gauze. The method, based upon the linearized theory due to Elder (1959), permits solutions for most practical cases to be obtained using relatively simple numerical techniques. Comparison with experimental data shows that the computed solutions are satisfactory provided the restrictions inherent in the linearized theory are observed.

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