Aerodynamic and Numerical Study on the Influence of Spike Shapes at Mach 1.5

2014 ◽  
Vol 1046 ◽  
pp. 177-181
Author(s):  
Yong Hong Li ◽  
Xin Wu Tang ◽  
Wei Qun Zhou
Keyword(s):  
Hypersonic Flow ◽  
Body Surface ◽  
Blunt Body ◽  
Numerical Study ◽  
Aerodynamic Characteristics ◽  
The Body ◽  
Bow Shock ◽  
Aerodynamic Heating ◽  
Recirculation Flow ◽  
Flight Vehicles

Taking into account the issue of configuration or aerodynamic heating, most supersonic and hypersonic flight vehicles have to use the blunt-nosed body. However, in supersonic especially in hypersonic flow the strong bow shock ahead of the blunt nose introduces a rather high shock drag that affects the aerodynamic performance of the vehicles seriously. A spike mounted on a blunt body during its flight pushes the strong bow shock away from the body surface and forms recirculation flow with low pressure ahead of the body surface, and then decreases the drag. The drag reduction effects of spikes in high supersonic and hypersonic flow had been validated through experimental and numerical methods. In order to analyze the influence of the spike on aerodynamic characteristics at low supersonic (M=1.5) flow past blunt-nosed bodies, numerical studies were carried out which included the influence of the spike shape, the analysis of the fluid flow structures and the effect on the aerodynamic characteristics of a blunt body.

Determination of the sonic line in hypersonic flow past a blunt body

1965 ◽  
Vol 21 (3) ◽  
pp. 495-501 ◽  
Author(s):  
M. I. G. Bloor
Keyword(s):  
Circular Cylinder ◽  
Hypersonic Flow ◽  
Body Surface ◽  
Blunt Body ◽  
The Body ◽  
Newtonian Theory ◽  
Plane Symmetric ◽  
Sonic Line ◽  
Subsonic Region

The Newtonian theory of inviscid hypersonic flow is extended to obtain a solution uniformly valid in the subsonic region, and that is used to determine the position and shape of the sonic line. The main modification to the theory has to be made near the body surface and an expansion, essentially in terms of the stream function, is employed.For simplicity the solution is limited to the cases of axially- and plane-symmetric flows. As an illustration of the theory the flows past a sphere and a circular cylinder are treated in some detail. Comparison with the numerical results of Garabedian and Lieberstein gives favourable agreement.

An experimental investigation of a two-layer inviscid shock cap due to blunt-body nose injection

1963 ◽  
Vol 15 (3) ◽  
pp. 442-448 ◽  
Author(s):  
Judson R. Baron ◽  
Edgar Alzner
Keyword(s):  
Experimental Investigation ◽  
Mach Number ◽  
Contact Surface ◽  
Blunt Body ◽  
The Body ◽  
Bow Shock ◽  
Mass Injection ◽  
Axisymmetric Channel ◽  
Injection Rates

Blunt-body solutions for suspersonic flow usually concern closed body surfaces. This paper reports on an experimental investigation of a two-layer shock cap and indicates the existence of a predictable contact surface separating the layers. The inner layer was generated by injecting air through a contoured axisymmetric channel on a blunt body so as to simulate a hemispherical contact surface in a Mach number 4.8 flow.Results show the existence of the contact surface and the influence of a range of mass-injection rates upon the displacement of the bow shock and contact surface from the body.

Simulation Research on Aerodynamic Characteristics of Vehicle under Steady Crosswind Based on XFlow

2014 ◽  
Vol 494-495 ◽  
pp. 138-141
Author(s):  
Shan Ling Han ◽  
Zhi Yong Li ◽  
Jin Bin Li ◽  
Ru Xing Yu
Keyword(s):  
Flow Field ◽  
Surface Pressure ◽  
Body Surface ◽  
Crucial Role ◽  
Aerodynamic Characteristics ◽  
The Body ◽  
Wake Flow ◽  
Aerodynamic Coefficient ◽  
Simulation Research ◽  
The Asymmetry

The aerodynamic characteristics of vehicle play a crucial role in steering stability, comfort and safety of vehicle. The crosswind will affect the aerodynamic characteristics of vehicle. In this paper, the aerodynamic characteristics of ASMO model under steady crosswind is simulated by XFlow software, and the changes of aerodynamic characteristics under different steady crosswind are analyzed. It turned out that the asymmetry of wake flow field is enhanced with the increasing of crosswind, and the body surface pressure of windward is amplified, the six components of aerodynamic coefficient are also increased. It is found that the vehicle aerodynamic characteristics changed obviously under steady crosswind.

On the viscous flow in the nose region of a symmetric blunt body in hypersonic flow

1966 ◽  
Vol 26 (4) ◽  
pp. 829-839 ◽  
Author(s):  
B. S. H. Rarity
Keyword(s):  
Hypersonic Flow ◽  
Blunt Body ◽  
Density Ratio ◽  
The Body ◽  
Entire Region ◽  
Nose Radius ◽  
Stagnation Line ◽  
Total Enthalpy ◽  
Post Shock ◽  
The Given

The flow field in the nose region of a blunt body in hypersonic flow is studied by considering the transport of vorticity and enthalpy. The entire region between body and shock is considered to be viscous, not necessarily thin in comparison with the nose radius of the body and to be of slowly varying density. The (given) post-shock vorticity need not be small and the density ratio ρ∞/ρs may either be small or near unity, the analysis being valid asymptotically at both limits.It is found that the vorticity equation may be uncoupled from the total enthalpy equation if μ√ρ is constant. While the equations are not expected to be necessarily restricted to the immediate vicinity of the stagnation line, only there can the solution be written down explicitly; elsewhere, numerical integration is required.

Hemodynamic impact of mitral prosthesis-patient mismatch on pulmonary hypertension: an in silico study

2008 ◽  
Vol 105 (6) ◽  
pp. 1916-1926 ◽  
Author(s):  
David Tanné ◽  
Lyes Kadem ◽  
Régis Rieu ◽  
Philippe Pibarot
Keyword(s):  
Pressure Gradient ◽  
Surface Area ◽  
Body Surface Area ◽  
Body Surface ◽  
Numerical Study ◽  
The Body ◽  
Effective Orifice Area ◽  
Cutoff Values ◽  
The Impact

Recent clinical studies reported that prosthesis-patient mismatch (PPM) becomes clinically relevant when the effective orifice area (EOA) indexed by the body surface area (iEOA) is <1.2–1.25 cm2/m2. To examine the effect of PPM on transmitral pressure gradient and left atrial (LA) and pulmonary arterial (PA) pressures and to validate the PPM cutoff values, we used a lumped model to compute instantaneous pressures, volumes, and flows into the left-sided heart and the pulmonary and systemic circulations. We simulated hemodynamic conditions at low cardiac output, at rest, and at three levels of exercise. The iEOA was varied from 0.44 to 1.67 cm2/m2. We normalized the mean pressure gradient by the square of mean mitral flow indexed by the body surface area to determine at which cutoff values of iEOA the impact of PPM becomes hemodynamically significant. In vivo data were used to validate the numerical study, which shows that small values of iEOA (severe PPM) induce high PA pressure (residual PA hypertension) and contribute to its nonnormalization following a valve replacement, providing a justification for implementation of operative strategies to prevent PPM. Furthermore, we emphasize the major impact of pulmonary resistance and compliance on PA pressure. The model suggests also that the cutoff iEOA that should be used to define PPM at rest in the mitral position is ∼1.16 cm2/m2. At higher levels of exercise, the threshold for iEOA is rather close to 1.5 cm2/m2. Severe PPM should be considered when iEOA is <0.94 cm2/m2 at rest.

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