Influences of lateral jet location and its number on the drag reduction of a blunted body in supersonic flows

2020 ◽  
Vol 124 (1277) ◽  
pp. 1055-1069 ◽  
Author(s):  
M. Dong ◽  
J. Liao ◽  
Z. Du ◽  
W. Huang
Keyword(s):  
Drag Reduction ◽  
Drag Force ◽  
Blunt Body ◽  
Stokes Equations ◽  
Supersonic Flows ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Reduction Strategies ◽  
Promising Application ◽  
Force Reduction

ABSTRACTThe analysis of the aerodynamic environment of the re-entry vehicle attaches great importance to the design of the novel drag reduction strategies, and the combinational spike and jet concept has shown promising application for the drag reduction in supersonic flows. In this paper, the drag force reduction mechanism induced by the combinational spike and lateral jet concept with the freestream Mach number being 5.9332 has been investigated numerically by means of the two-dimensional axisymmetric Navier-Stokes equations coupled with the shear stress transport (SST) k-ω turbulence model, and the effects of the lateral jet location and its number on the drag reduction of the blunt body have been evaluated. The obtained results show that the drag force of the blunt body can be reduced more profoundly when employing the dual lateral jets, and its maximum percentage is 38.81%, with the locations of the first and second lateral jets arranged suitably. The interaction between the leading shock wave and the first lateral jet has a great impact on the drag force reduction. The drag force reduction is more evident when the interaction is stronger. Due to the inclusion of the lateral jet, the pressure intensity at the reattachment point of the blunt body decreases sharply, as well as the temperature near the walls of the spike and the blunt body, and this implies that the multi-lateral jet is beneficial for the drag reduction.

Drag and Heat Reduction Mechanism of the Porous Opposing Jet for Variable Blunt Hypersonic Vehicles

2018 ◽  
Author(s):  
Shibin Li ◽  
Wei Huang ◽  
Zhenguo Wang ◽  
Li Yan
Keyword(s):  
Drag Reduction ◽  
Stokes Equations ◽  
Thermal Protection ◽  
Three Dimensional ◽  
Optimal Solution ◽  
Mach Disk ◽  
Hypersonic Vehicle ◽  
Navier Stokes ◽  
Hypersonic Vehicles ◽  
Navier Stokes Equations

Opposing jet, as one of the most practical strategies to achieve the drag and heat reduction, is usually adopted to improve the aerodynamics and the aerothermodynamics of hypersonic vehicles. The porous jet strategy which is suitable for the blunt hypersonic vehicle has been proposed and investigated numerically in this study. The full Navier-Stokes equations and SST k-w turbulence model is used to obtain the flow field properties. The numerical method is validated by the wind tunnel experimental data. This work shows that the porous opposing jet is able to reduce the drag and the aero-heating of blunt hypersonic vehicles. The aerodynamic performance can be improved further by combining the porous jet design with variable blunt methods. When the number of jet orifices (N) is an odd number, the area of Mach disk and the off-distance of shock wave decrease with the increase in N. When N is an even number, the high temperature region will decrease with the increase in N. The drag reduction ratio increases with the increase of jet orifices when N is an odd number. However, the trend is contrary when N is even. Moreover, when N is odd, the effect of drag reduction is better than that when N is even. Considering both factors of the drag reduction and thermal protection, the porous jet design is useful in improving the overall performance of the blunt hypersonic vehicle. The porous jet has three-dimensional effect, so there exists the optimal injection scheme. The three factors (the number, the spacing and the radius of injection orifices) have a multi-objective optimal solution. It is thus then the drag reduction and the heat protection of the porous jet injection has the best performance.

scholarly journals On the viscous hypersonic blunt body problem

1964 ◽  
Vol 20 (3) ◽  
pp. 353-367 ◽  
Author(s):  
William B. Bush
Keyword(s):  
Blunt Body ◽  
Free Stream ◽  
Stokes Equations ◽  
Viscosity Coefficient ◽  
Absolute Temperature ◽  
The Body ◽  
Navier Stokes ◽  
Nose Radius ◽  
Navier Stokes Equations ◽  
Specific Heats

The viscous hypersonic flow past an axisymmetric blunt body is analysed based upon the Navier-Stokes equations. It is assumed that the fluid is a perfect gas having constant specific heats, a constant Prandtl number, P, whose numerical value is of order one, and a viscosity coefficient varying as a power, ω, of the absolute temperature. Limiting forms of solutions are studied as the free-stream Mach number, M, and the free-stream Reynolds number based on the body nose radius, R, go to infinity, and ε = (γ − 1)/(γ + 1), where γ is the ratio of the specific heats, and δ = 1/(γ − 1) M2 go to zero.

Effect of Riblets Geometry on Drag Reduction

2012 ◽  
Author(s):  
Ekhlas M. Fayyadh ◽  
Nibras M. Mahdi
Keyword(s):  
Drag Reduction ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Turbulent Regime ◽  
Governing Equations ◽  
Navier Stokes Equations ◽  
Total Drag ◽  
Surface Models ◽  
Smooth Model ◽  
Riblet Surface

The effect of longitudinal riblet surface models (U, V and semi-Circular and U with fillet corner riblets) on the performance of unsymmetrical airfoil NACA23015 which has been investigated numerically and experimentally. Numerical investigation involve examining drag reduction by solving the governing equations (Continuity and Navier-Stokes equations) using the known package FLUENT in turbulent regime with appropriate turbulence model (κ-ε). Also measurement in experimental work will be carried out. The results indicate that the riblet surface models are the key parameters for controlling the boundary layer characteristics. The most effective riblet surface is U-riblet with fillet model (Mo.4, h = 0.1mm), by compare to smooth model, the results show a small increment in lift slope curve about 9% and total drag decrease 12% over the angles of attack range from (0° to 17°).

scholarly journals Evidence of Landau Damping in a Fluid Coupled with an Anharmonic Lattice

2018 ◽  
Author(s):  
Andrei Ludu ◽  
Eric Padilla ◽  
M. A. Qaayum Mazumder
Keyword(s):  
Drag Force ◽  
Water Waves ◽  
Stokes Equations ◽  
Collisionless Plasma ◽  
Rogue Waves ◽  
Landau Damping ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Anharmonic Lattice ◽  
Specific Frequency

The Landau damping effect was observed in collisionless plasma, as a microscopic resonant mechanism between electromagnetic radiation and the collective modes. In this paper we demonstrate the occurrence of the Landau damping at macroscopic scale in the interaction between water waves and anharmonic lattice of magnetic buoys. By coupling the Navier-Stokes equations for incompressible fluid with the nonlinear dynamics of an anharmonic magnetic lattice we obtain a resonant transfer of momentum and energy between the two systems. The velocity of the flow is obtained in the Stokes approximation with Basset type of drag force. The dynamics of the buoys is calculated in the surfactant approximation for a specific frequency, then we use Fourier analysis to obtain the general time variable interaction. After involving an integral Dirichlet transform we obtain the time dependent expression of the drag force, the interaction waves-lattice with a new term in the form of a Caputo fractional derivative. We compare the results of the model with experiments performed in a wave tank with free floating magnetic buoys under the action of small amplitude gravitational waves. This configuration can be applied in studies for the attenuation with resonant damping of rogue waves, storms or tsunamis.

scholarly journals Optimization of artillery projectiles base drag reduction using hot base flow

2019 ◽  
Vol 23 (1) ◽  
pp. 353-364
Author(s):  
Mohammed Dali ◽  
Slobodan Jaramaz
Keyword(s):  
Drag Reduction ◽  
Stokes Equations ◽  
Flow Characteristics ◽  
Turbulence Models ◽  
Combustion Products ◽  
Base Flow ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Base Bleed ◽  
Base Drag

The CFD numerical simulations were carried out to investigate the base drag characteristics of a projectile with base bleed unit with a central jet. Different base bleed grain types with different combustion temperatures were used. The goal was to find a way to effectively control the base flow for base drag reduction and optimisate the latter using an adequate CFD software. Axisymmetric, compressible, mass-averaged Navier-Stokes equations are solved using the k-? SST, transition k-kl-?, and RSM turbulence models. The various base flow characteristics are obtained by the change in the non-dimensionalized injection impulse. The results obtained through the present study show that there is an optimum bleed condition for all base bleed grains tested. That optimum is dependent on the temperature of the grain combustion products. The optimum reduces the total drag for 6,9% in the case of air injection at temperature of 300 K and reaches up to 28% in the case of propellant combustion products injection at almost 2500 K. Besides, the increasing of molecular weight has a role no less important than temperature of the combustion products in terms of base drag reduction.

Supercomputing of Supersonic Flows Using Upwind Relaxation and MacCormack Schemes

1988 ◽  
Vol 110 (1) ◽  
pp. 62-68 ◽  
Author(s):  
Oktay Baysal
Keyword(s):  
Stokes Equations ◽  
Supersonic Flows ◽  
Navier Stokes ◽  
Computational Algorithms ◽  
Navier Stokes Equations ◽  
Relaxation Scheme ◽  
Finite Volume Discretization ◽  
Finite Difference Discretization ◽  
The Mathematical Model ◽  
Difference Discretization

The impetus of this paper is the comparative applications of two numerical schemes for supersonic flows using computational algorithms tailored for a supercomputer. The mathematical model is the conservation form of Navier-Stokes equations with the effect of turbulence being modeled algebraically. The first scheme is an implicit, unfactored, upwind-biased, line-Gauss-Seidel relaxation scheme based on finite-volume discretization. The second scheme is the explicit-implicit MacCormack scheme based on finite-difference discretization. The best overall efficiences are obtained using the upwind relaxation scheme. The integrity of the solutions obtained for the example cases is shown by comparisons with experimental and other computational results.

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