scholarly journals Effect of intermediate aerodisk mounted sharp tip spike on the drag reduction over a hemispherical body at Mach 2.0

2020 ◽  
Vol 48 (4) ◽  
pp. 779-786
Author(s):  
Payal Tembhurnikar ◽  
Akash Jadhav ◽  
Devabrata Sahoo
Keyword(s):  
Mach Number ◽  
Shock Waves ◽  
Drag Reduction ◽  
High Speed ◽  
Blunt Body ◽  
Critical Length ◽  
Computational Studies ◽  
Supersonic Speed ◽  
Zero Degree ◽  
Shock System

Reduction of forebody drag in high speed flying vehicles such as rockets and missiles are of high research interest in the present time. In the present research, drag reduction obtained by using an intermediate aerodisk mounted sharp tip spike has been investigated using computational studies at Mach number of 2.0. The flowfield over a hemispherical blunt body with an intermediate aerodisk mounted sharp tip spike is investigated at zero degree angle of attack and the amount of drag reduction obtained is then compared with that of a conventional sharp tip spike mounted hemisphere. The presence of an intermediate aerodisk changes the flow physics and shock system over the blunt body. The change in the system of shock waves by mounting an intermediate aerodisk results in a higher percentage (20% higher) of drag reduction generated by the blunt spiked body moving at a supersonic speed of Mach 2.0. Use of intermediate aerodisk proves to be beneficial in terms of drag reduction for spike lengths ranging beyond the critical length.

A numerical study on the single pulsed energy addition based unsteady wave drag reduction at varied hypersonic flow regimes

2020 ◽  
pp. 095441002097313
Author(s):  
Dathi SNV Rajasekhar Rao ◽  
Bibin John
Keyword(s):  
Steady State ◽  
Mach Number ◽  
Drag Reduction ◽  
Shock Layer ◽  
Blunt Body ◽  
Wave Drag ◽  
Flow Features ◽  
Energy Pulse ◽  
Energy Addition ◽  
Wave Drag Reduction

In this study, unsteady wave drag reduction in hypersonic flowfield using pulsed energy addition is numerically investigated. A single energy pulse is considered to analyze the time-averaged drag reduction/pulse. The blast wave creation, translation and its interaction with shock layer are studied. As the wave drag depends only on the inviscid aspects of the flowfield, Euler part of a well-established compressible flow Navier-Stokes solver USHAS (Unstructured Solver for Hypersonic Aerothermodynamics) is employed for the present study. To explore the feasibility of pulsed energy addition in reducing the wave drag at different flight conditions, flight Mach numbers of 5.75, 6.9 and 8.0 are chosen for the study. An [Formula: see text] apex angle blunt cone model is considered to be placed in such hypersonic streams, and steady-state drag and unsteady drag reductions are computed. The simulation results indicate that drag of the blunt-body can be reduced below the steady-state drag for a significant period of energy bubble-shock layer interaction, and the corresponding propulsive energy savings can be up to 9%. For energy pulse of magnitude 100mJ deposited to a spherical region of 2 mm radius, located 50 mm upstream of the blunt-body offered a maximum percentage of wave drag reduction in the case of Mach 8.0 flowfield. Two different flow features are found to be responsible for the drag reduction, one is the low-density core of the blast wave and the second one is the baroclinic vortex created due to the plasma energy bubble-shock layer interaction. For the same freestream stagnation conditions, these two flow features are noted to be very predominant in the case of high Mach number flow in comparison to Mach 5.75 and 6.9 cases. However, the ratio of energy saved to the energy consumed is noted as a maximum for the lower Mach number case.

Study of High Speed Turbulent Flow Over Rotating Two Stage Three Dimensional Double Wedge

2006 ◽  
Author(s):  
Khaled Alhussan
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Mach Number ◽  
Shock Waves ◽  
High Speed ◽  
Three Dimensional ◽  
Oblique Shock ◽  
Wave Interactions ◽  
Double Wedge ◽  
Slip Surfaces

In this paper some characteristics of non-steady, compressible, flow are explored, including compression and expansion wave interactions and creation. The work to be presented herein is a Computational Fluid Dynamics investigation of the complex fluid phenomena that occur inside three-dimensional region, specifically with regard to the structure of the oblique shock waves, the reflected shock waves and the interactions of the shock waves. The flow is so complex that there exist oblique shock waves, expansion fans, slip surfaces, and shock wave interactions and reflections. The flow is non-steady, turbulent, viscous, compressible, and high-speed supersonic. The work to be presented herein is a Computational Fluid Dynamics analysis of flow over a 15-degree angle double wedge for a compressible air, with spin angle of 10-degree and Mach number of 2.5. The problem to be solved involves formation of shock waves, expansion fans and slip surfaces, so that the general characteristics of supersonic flow are explored through this problem. Shock waves and slip surfaces are discontinuities in fluid mechanics problems. It is essential to evaluate the ability of numerical technique that can solve problems in which shocks and contact surfaces occur. In particular it is necessary to understand the details of developing a mesh that will allow resolution of these discontinuities. Results including contour plots of pressure, temperature, and Mach number will show that CFD is capable of predicting accurate results and is also able to capture the discontinuities in the flow, e.g., the oblique shock waves and the slip surfaces. Through this computational analysis, a better interpretation of the physical phenomenon of the three-dimensional shock waves interaction and reflection can be achieved.

scholarly journals The onset of compressibility effects for aerofoils in ground effect

2007 ◽  
Vol 111 (1126) ◽  
pp. 797-806 ◽  
Author(s):  
G. Doig ◽  
T. J. Barber ◽  
E. Leonardi ◽  
A. J. Neely
Keyword(s):  
Mach Number ◽  
High Speed ◽  
Subsonic Flow ◽  
Flow Characteristics ◽  
Ground Effect ◽  
Aerodynamic Performance ◽  
Computational Studies ◽  
Pressure Gradients ◽  
Cfd Simulations ◽  
Compressibility Effects

Abstract The influence of flow compressibility on a highly-cambered inverted aerofoil in ground effect is presented, based on two-dimensional computational studies. This type of problem has relevance to open-wheel racing cars, where local regions of high-speed subsonic flow form under favourable pressure gradients, even though the maximum freestream Mach number is typically considerably less than Mach 0·3. An important consideration for CFD users in this field is addressed in this paper: the freestream Mach number at which flow compressibility significantly affects aerodynamic performance. More broadly, for aerodynamicists, the consequences of this are also considered. Comparisons between incompressible and compressible CFD simulations are used to identify important changes to the flow characteristics caused by density changes, highlighting the inappropriateness of incompressible simulations of ground effect flows for freestream Mach numbers as low as 0·15.

scholarly journals Computational Analysis of High Speed Flow Over a Double-Wedge for Air as Working Fluid

2005 ◽  
Author(s):  
Khaled Alhussan
Keyword(s):  
Mach Number ◽  
Shock Waves ◽  
High Speed ◽  
Numerical Technique ◽  
Working Fluid ◽  
Double Wedge ◽  
Slip Surfaces ◽  
Global Comparison ◽  
Computational Fluid Dynamics Analysis ◽  
Contour Plots

The work to be presented herein is a Computational Fluid Dynamics analysis of flow over a 15-degree angle double wedge for a compressible air, with Mach number of 2.95. The problem to be solved involves formation of shock waves, expansion fans and slip surfaces, so that the general characteristics of supersonic flow are explored through this problem. Shock waves and slip surfaces are discontinuities in fluid mechanics problems. It is essential to evaluate the ability of numerical technique that can solve problems in which shocks and contact surfaces occur. In particular it is necessary to understand the details of developing a mesh that will allow resolution of these discontinuities. Results including contour plots of pressure, temperature, density and Mach number will show that CFD is capable of predicting accurate results and is also able to capture the discontinuities in the flow, e.g., the oblique shock waves and the slip surfaces. The global comparison of some parameters between the numerical and the analytical values show a good agreement.

Some Low Speed Problems of High Speed Aircraft

1962 ◽  
Vol 66 (616) ◽  
pp. 211-225 ◽  
Author(s):  
A. Spence ◽  
D. Lean
Keyword(s):  
Mach Number ◽  
High Speed ◽  
Supersonic Speed ◽  
Jet Propulsion ◽  
Low Speed ◽  
The Past ◽  
Flight Range ◽  
The Future ◽  
Mach Numbers ◽  
Leading Edges

The high speed aircraft whose low speed aerodynamic problems are discussed in this part of the paper belong to the future rather than to the past or present. Küchemann has shown how jet propulsion and the use of a new set of aerodynamics appropriate to supersonic speed lead one from the classical aircraft to new shapes suitable for achieving a required flight range. These shapes include wing-body arrangements with wing sweepback angles of 55° or 60° suitable for a Mach number of about 1·2, and slender, neartriangular wings with sharp leading edges suitable for Mach numbers of around 2 or more, depending on the ratio of span to length.

scholarly journals Effects of Heat Addition on Wave Drag Reduction of a Spiked Blunt Body

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Hongyu Wang ◽  
Yanguang Yang ◽  
Langquan Li ◽  
Gang Wang ◽  
Qinghu Zhang
Keyword(s):  
Drag Reduction ◽  
High Speed ◽  
Blunt Body ◽  
Wave Drag ◽  
The Body ◽  
Continuous Heating ◽  
Heat Addition ◽  
Reduction Coefficient ◽  
Wave Drag Reduction ◽  
High Speed Vehicle

Drag reduction technology plays a significant role in extending the flight range for a high-speed vehicle. A wave drag reduction strategy via heat addition to a blunt body with a spike was proposed and numerically validated. The heat addition is simulated with continuous heating in a confined area upstream of the blunt body. The effects of heat addition on drag reduction in three flow conditions ( M = 3.98 , 5 , 6 ) were compared, and the influence of power density q h ( q 1 = 2.0 × 10 8   W / m 3 , q 2 = 5.0 × 10 8   W / m 3 , and q 3 = 1.0 × 10 9   W / m 3 ) of heating was evaluated. Results show that the heat addition has a positive way to reduce the drag of the body with a spike alone, and more satisfactory drag reduction effectiveness can be achieved at a higher Mach number. The drag reduction coefficient increases with q h in the same flow condition, with a maximum of 38.9% ( M = 6 ) as q 3 = 1.0 × 10 9   W / m 3 . The wave drag reduction principle was discussed by a transient calculation, which indicates that the separation region has entrainment of the heated air and expanded with its sonic line away from the blunt cone, which results in an alleviation of the pressure load caused by shock/shock interaction.

Power Plants for High–Speed Aircraft

1951 ◽  
Vol 55 (490) ◽  
pp. 642-650 ◽  
Author(s):  
A. D. Baxter
Keyword(s):  
Mach Number ◽  
Shock Waves ◽  
High Speed ◽  
Power Plants ◽  
Ground Level ◽  
Jet Propulsion ◽  
Supersonic Aircraft ◽  
Ordinary Power ◽  
The Difference ◽  
Transonic Region

A few years ago when high–speed aircraft were mentioned, speeds of 300 to 400 m.p.h. came to mind. The advent of jet propulsion has made those figures 100 per cent, out of date and today speeds are discussed more and more in terms of Mach number; for example, high–speed subsonic aircraft fly at Mach numbers of 0.85 to 0.90, aircraft are flying in the transonic region and supersonic guided missiles are proposed for speeds anywhere between M=1.5 and 2.5, i.e. ground level speeds up to 2,000 m.p.h.It is proposed to review very broadly the suitability of propulsion units for these transonic and supersonic applications. What is the difference between ordinary power plants and those for high speed? The answer might be contained in another question—why are supersonic aircraft different from conventional types? The aerodynamicist will give an involved explanation concerned with compressibility, drag rise, shock waves, and so on.

Drag Reduction Performance due to Repetitive Laser Pulses on the Blunt Body

2011 ◽  
Author(s):  
Jae-Hyung Kim ◽  
Akihiro Sasoh
Keyword(s):  
Drag Reduction ◽  
High Speed ◽  
Energy Deposition ◽  
Blunt Body ◽  
Laser Pulses ◽  
Wave Drag ◽  
Force Balance ◽  
Balance System ◽  
Convex Lens ◽  
Wave Drag Reduction

Supersonic wave drag reduction due to the repetitive laser induced energy deposition is performed experimentally in this study. Laser pulses are irradiated through a convex lens installed in side of the in-draft wind tunnel of Mach 1.94. The maximum frequency and power of the energy deposition is limited up to 50kHz and 400W. In order to estimate the drag reduction, time-averaged drag force is measured by a force balance system and stagnation pressure history is synchronized with corresponding sequential schlieren images captured by high-speed camera. Drag reduction performance is linearly increased up to 21% with input laser power. The power gain which only depends on the pulse energy, is realized by approximately 7. Virtual spike formation induced by highrepetitive energy depositions is remarkably discussed in the visualization results.

scholarly journals Mach Number Effect on Supersonic Drag Reduction using Repetitive Laser Energy Depositions over a Blunt Body

2017 ◽  
Vol 60 (5) ◽  
pp. 303-311 ◽  
Author(s):  
Akira IWAKAWA ◽  
Tatsuro SHODA ◽  
Ryosuke MAJIMA ◽  
Son Hoang PHAM ◽  
Akihiro SASOH
Keyword(s):  
Mach Number ◽  
Drag Reduction ◽  
Blunt Body ◽  
Laser Energy
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