Two-Dimensional Boat-Tailed Bases in Supersonic Flow

1974 ◽  
Vol 25 (3) ◽  
pp. 210-224 ◽  
Author(s):  
P R Viswanath ◽  
R Narasimha
Keyword(s):  
Boundary Layer ◽  
Supersonic Flow ◽  
Free Stream ◽  
The Body ◽  
Base Pressure ◽  
Two Dimensional ◽  
Sharp Corner ◽  
Boundary Layer Effect ◽  
Pressure Distributions ◽  
Layer Effect

SummaryBoat-tailing of aft bodies may affect the base pressure through two mechanisms: firstly by changing the angle between the approaching flow at separation and the reattachment surface, and secondly by distorting the boundary layer through the favourable pressure gradient (which can be particularly severe in the presence of a sharp corner on the body). The first effect is isolated here by tests on inclined backward-facing steps with a fully developed turbulent boundary layer at separation, at free-stream Mach numbers of 1.75 and 2.4. It is found that the base pressure increases significantly with boat-tail angle; the data have been correlated taking explicit account of the boundary layer effect, modifying and extending the approach adopted by Nash. Charts are provided for quick estimation of base pressure in engineering calculations. Some of the earlier data on boat-tailed bases, on re-examination in the light of the present correlation, suggest that strongly distorted boundary layers at separation affect the base pressure appreciably. Several features of the measured reattachment pressure distributions, including their internal similarity, are also discussed.

Two Different Theoretical Approaches to the Base Pressure Problem in Two-Dimensional Supersonic Flow

1978 ◽  
Vol 29 (2) ◽  
pp. 114-130 ◽  
Author(s):  
M. Tanner
Keyword(s):  
Supersonic Flow ◽  
Flow Model ◽  
The Body ◽  
Experimental Results ◽  
Base Pressure ◽  
Two Dimensional ◽  
Reattachment Point ◽  
Fundamental Idea ◽  
Entropy Increase ◽  
Theoretical Approaches

SummaryThe basic physical idea underlying the theories based on the flow model of CHAPMAN and KORST is that the base pressure can be predicted if the pressure at the reattachment point is known. In the new theory of TANNER the fundamental idea is the connection between the drag of the body and the entropy increase in the flow. This paper presents the essence of both theories together with theoretical and experimental results.

Irrotational Flow Within the Boundary Layer and Wake

1982 ◽  
Vol 26 (04) ◽  
pp. 219-228
Author(s):  
Louis Landweber
Keyword(s):  
Boundary Layer ◽  
The Body ◽  
Two Dimensional ◽  
Irrotational Flow ◽  
Pressure Coefficients ◽  
Pressure Distributions ◽  
Boundary Layer Region ◽  
Symmetrical Body ◽  
The Difference ◽  
Layer Region

Expressions are derived for centerplane source distributions which generate an irrotational flow field about a laterally symmetrical body that matches that exterior to the boundary layer and wake. Results are given for two-dimensional bodies and thin-ship forms. Pressure distributions at the wall of a two-dimensional body are determined for the flow in the boundary-layer region with and without vorticity. The difference between the pressure coefficients is shown to be principally proportional to the product of the surface curvature of the body by the sum of the displacement and momentum thicknesses.

Effects of forebody boundary layer on the performance of a submerged inlet

2021 ◽  
pp. 1-22
Author(s):  
W.Z. Xie ◽  
S.Z. Yang ◽  
C. Zeng ◽  
K. Liao ◽  
R.H. Ding ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Energy Flow ◽  
Total Pressure ◽  
Free Stream ◽  
Aerodynamic Characteristics ◽  
Aerodynamic Performance ◽  
Low Energy ◽  
Boundary Layer Effect ◽  
Sideslip Angle ◽  
Layer Effect

ABSTRACT The use of a submerged inlet is advantageous in modern aircrafts because of its low drag resistance, small radar cross section and ease of maintenance. Although it is well known that the forebody boundary layer deteriorates the aerodynamic performance of a submerged inlet, the level of impact has not yet been fully quantified. To quantify the forebody boundary-layer effect, a submerged diverter was designed to remove a portion of the low-energy boundary flow. The flow pattern and aerodynamic performance of a submerged inlet, with and without the diverter, were investigated by wind-tunnel experimentation and numerical simulations. The effects of mass flow, free stream speed, angle-of-attack and sideslip angle on the aerodynamic characteristics of the inlet with and without the submerged diverter were studied, over an operating envelope of M 0 = 0.3 ∼ 0.6, $\alpha$ = –6 $^{\circ}$ ∼ 8 $^{\circ}$ and $\beta$ = 0 $^{\circ}$ ∼ 4 $^{\circ}$ . The results indicate that both the total pressure loss and the circumferential distortion can be significantly reduced with the removal of the forebody boundary-layer low-energy flow. Meanwhile, the main mechanisms for losses in the submerged inlet were also analysed.

The Departure from Equilibrium of Turbulent Boundary Layers

1968 ◽  
Vol 19 (1) ◽  
pp. 1-19 ◽  
Author(s):  
H. McDonald
Keyword(s):  
Boundary Layer ◽  
Shear Stress ◽  
Kinetic Energy ◽  
Stress Distribution ◽  
Boundary Layers ◽  
Turbulent Boundary Layers ◽  
Two Dimensional ◽  
Pressure Distributions ◽  
Momentum Integral ◽  
State Examination

SummaryRecently two authors, Nash and Goldberg, have suggested, intuitively, that the rate at which the shear stress distribution in an incompressible, two-dimensional, turbulent boundary layer would return to its equilibrium value is directly proportional to the extent of the departure from the equilibrium state. Examination of the behaviour of the integral properties of the boundary layer supports this hypothesis. In the present paper a relationship similar to the suggestion of Nash and Goldberg is derived from the local balance of the kinetic energy of the turbulence. Coupling this simple derived relationship to the boundary layer momentum and moment-of-momentum integral equations results in quite accurate predictions of the behaviour of non-equilibrium turbulent boundary layers in arbitrary adverse (given) pressure distributions.

Boundary Layer Closure and Heat Transfer in Constant Base Pressure and Simple Wave Guns

1978 ◽  
Vol 100 (4) ◽  
pp. 690-696 ◽  
Author(s):  
A. D. Anderson ◽  
T. J. Dahm
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Layer Thickness ◽  
Boundary Layer Thickness ◽  
Method Of Characteristics ◽  
Simple Wave ◽  
Momentum Equation ◽  
Base Pressure ◽  
Two Dimensional ◽  
The Method Of Characteristics

Solutions of the two-dimensional, unsteady integral momentum equation are obtained via the method of characteristics for two limiting modes of light gas launcher operation, the “constant base pressure gun” and the “simple wave gun”. Example predictions of boundary layer thickness and heat transfer are presented for a particular 1 in. hydrogen gun operated in each of these modes. Results for the constant base pressure gun are also presented in an approximate, more general form.

Measurement of Recovery Factors and Friction Coefficients for Supersonic Flow of Air in a Tube: 2—Results Based on a Two-Dimensional Flow Model for Entrance Region

1952 ◽  
Vol 19 (2) ◽  
pp. 185-194
Author(s):  
J. Kaye ◽  
T. Y. Toong ◽  
R. H. Shoulberg
Keyword(s):  
Boundary Layer ◽  
Supersonic Flow ◽  
Laminar Boundary Layer ◽  
Flow Model ◽  
Variable Mass ◽  
Entrance Region ◽  
Two Dimensional ◽  
Dimensional Flow ◽  
Change Of State ◽  
Two Dimensional Flow

Abstract The first part of a program to obtain reliable data on the rate of heat transfer to air moving at supersonic speeds in a tube has been devoted to measurements made on adiabatic supersonic flow of air in a tube. The details of these measurements have been described in a previous paper. The calculated quantities such as the local apparent friction coefficient, recovery factor, Mach number, and so forth, were obtained from the simple one-dimensional flow model for which the properties of the stream are uniform at any section, and boundary-layer effects are ignored. The analysis of some of the same data given in the previous paper is undertaken here with the aid of a simplified two-dimensional flow model. The supersonic flow in the tube is divided into a supersonic core of variable mass with the fluid remaining in the core undergoing a reversible adiabatic change of state, and a laminar boundary layer of variable mass. The compressible laminar boundary layer increases in thickness in the direction of flow, and then undergoes a transition to a turbulent boundary layer. The two-dimensional flow model is limited here to the region where a laminar boundary layer appears to be present in the entrance region of the tube. The results of the analysis based on the two-dimensional flow model indicate that where the flow in the tube boundary layer appears to be laminar, the measured pressures and temperatures in the tube for adiabatic supersonic flow of air could have been predicted, with sufficient accuracy for engineering problems, from measured data for supersonic flow of air over a flat plate with a laminar boundary layer, and with zero pressure gradient.

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