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In aerodynamics, hypersonic speeds are speeds that are highly supersonic. In the 1970s, the term generally came to refer to speeds of Mach 5 and above. The hypersonic regime is a subset of the supersonic regime. Image File history File links Download high-resolution version (3030x2606, 2081 KB) Hyper - X at Mach 7: This computational fluid dynamic (CFD) image is of the Hyper - X at the Mach 7 test condition with the engine operating. ...
Image File history File links Download high-resolution version (3030x2606, 2081 KB) Hyper - X at Mach 7: This computational fluid dynamic (CFD) image is of the Hyper - X at the Mach 7 test condition with the engine operating. ...
NASA technicians working on the X-43A at the tip of a Pegasus rocket attached to a Boeing B-52B prior to launch (March 27, 2004) The X-43 is an unmanned experimental hypersonic aircraft design with multiple planned scale variations meant to test different aspects of highly supersonic flight. ...
This article is about the branch of Physics. ...
It has been suggested that hypersonic be merged into this article or section. ...
1970 (MCMLXX) was a common year starting on Thursday (the link is to a full 1970 calendar). ...
An F/A-18 Hornet approaching the sound barrier. ...
Supersonic airflow is decidedly different from subsonic flow. Nearly everything about the way an aircraft flies changes dramatically as an aircraft accelerates to supersonic speeds. Even with this strong demarcation, there is still some debate as to the definition of "supersonic". One definition is that the aircraft, as a whole, is traveling at Mach 1 or greater. More technical definitions state that you are only supersonic if the airflow over the entire aircraft is supersonic, which occurs around Mach 1.2 on typical designs. The range Mach 0.8 to 1.2 is therefore considered transonic. Transonic is an aeronautics term referring to a range of velocities just below and above the speed of sound. ...
Considering the problems with this simple definition, it should be no surprise that a definition of hypersonic would be even more difficult, considering that there is no physical change in airflow that makes it "hyper." Generally, a combination of effects become important "as a whole" around Mach 5. The hypersonic regime is often defined as speeds where ramjets do not produce net thrust. This is a nebulous definition in itself, as there exists a proposed change to allow them to operate in the hypersonic regime (the Scramjet). A ramjet, sometimes referred to as a stovepipe jet, is a type of jet engine. ...
X-43A with scramjet attached to the underside at Mach 7 A scramjet (supersonic combustion ramjet) is a variation of a ramjet where the flow of the air and combustion of the fuel air mixture through the engine happen at supersonic speeds. ...
Hypersonic effects The hypersonic flow regime is characterized by a number of effects which are not found in typical aircraft operating at low subsonic Mach numbers. The effects depend strongly on the speed and type of vehicle under investigation. Mach may refer to: Ernst Mach Mach number, as a measure of speed inertial mass GNU Mach The microkernel on which GNU Hurd is based Mach kernel, an operating systems kernel technology used in Mac OS X Mach band, an optical illusion Mach Five, the name of the car in...
Hypersonic similarity parameters The categorization of airflow relies on a number of similarity parameters, which allow the simplification of a nearly infinite number of test cases into groups of similarity. For transonic and compressible flow, the Mach and Reynolds numbers alone allow good categorization of many flow cases. In the physical sciences, a dimensionless number (or more precisely, a number with the dimensions of 1) is a quantity which describes a certain physical system and which is a pure number without any physical units; it does not change if one alters ones system of units of measurement...
Fluid Dynamics Compressibility (physics) is a measure of the relative volume change of fluid or solid as a response to a pressure (or mean stress) change: . For a gas the magnitude of the compressibility depends strongly on whether the process is adiabatic or isothermal, while this difference is small in...
An F/A-18 Hornet approaching the sound barrier. ...
The Reynolds number is the ratio of inertial forces (vsÏ) to viscous forces (μ/L) and is used for determining whether a flow will be laminar or turbulent. ...
Hypersonic flows, however, require other similarity parameters. Firstly, the analytic equations for the Oblique shock angle become nearly independent of Mach number at high (~>10) Mach numbers. Secondly, the formation of strong shocks around aerodynamic bodies mean that the freestream Reynolds number is less useful as an estimate of the behavior of the boundary layer over a body (although it is still important). Finally, the increased temperature of hypersonic flows mean that real gas effects become important. For this reason, research in hypersonics is often referred to as aerothermodynamics, rather than aerodynamics. Introduction The shock wave is one of several different ways in which a gas in a supersonic flow can be compressed. ...
In physics and fluid mechanics, the boundary layer is that layer of fluid in the immediate vicinity of a bounding surface. ...
An ideal gas (also called a perfect gas) is a hypothetical fluid consisting of particles that are identical to each other, occupy negligible volume and undergo perfect elastic collisions with each other, with no intermolecular forces and no intramolecular storage of energy, as opposed to a real gas, a gas...
This article is about the branch of Physics. ...
The introduction of real gas effects mean that more variables are required to describe the full state of a gas. Whereas a stationary gas can be described by three variables (pressure, temperature, adiabatic index), and a moving gas by four (velocity), a hot gas in chemical equilibrium also requires state equations for the chemical components of the gas, and a gas in nonequilibrium solves those state equations using time as an extra variable. This means that for a nonequilibrium flow, something between 10 and 100 variables may be required to describe the state of the gas at any given time. Additionally, rarefied hypersonic flows (usually defined as those with a Knudsen number below one) do not follow the Navier-Stokes equations. The use of water pressure - the Captain Cook Memorial Jet in Lake Burley Griffin, Canberra. ...
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The adiabatic index of a gas, is the ratio of its specific heat capacity at constant pressure (CP) to its specific heat capacity at constant volume (CV). ...
The velocity of an object is simply its speed in a particular direction. ...
The Knudsen number (Kn) is the ratio of the molecular mean free path length to a representative physical length scale. ...
The Navier-Stokes equations, named after Claude-Louis Navier and George Gabriel Stokes, are a set of equations that describe the motion of fluid substances like liquids and gases. ...
Hypersonic flows are typically categorized by their total energy, expressed as total enthalpy (MJ/kg), total pressure (kPa-MPa), stagnation pressure (kPa-MPa), stagnation temperature (K), or velocity (km/s). In thermodynamics and molecular chemistry, the enthalpy or heat content (denoted as Δ or ΔH, or rarely as χ) is a quotient or description of thermodynamic potential of a system, which can be used to calculate the useful work obtainable from a closed thermodynamic system under constant conditions. ...
Hypersonic regimes Hypersonic flow can be approximately separated into a number of regimes. The selection of these regimes is rough, due to the blurring of the boundaries where a particular effect can be found.
Perfect gas In this regime, the gas can be regarded as an ideal gas. Flow in this regime is still Mach number dependent. Simulations start to depend on the use of a constant-temperature wall, rather than the adiabatic wall typically used at lower speeds. The lower border of this region is around Mach 5, where Ramjets become inefficient, and the upper border around Mach 10-12. An ideal gas or perfect gas is a hypothetical gas consisting of identical particles of negligible volume, with no intermolecular forces. ...
Two-temperature ideal gas This is a subset of the perfect gas regime, where the gas can be considered chemically perfect, but the rotational and vibrational temperatures of the gas must be considered separately, leading to two temperature models. See particularly the modeling of supersonic nozzles, where vibrational freezing becomes important.
Dissociated gas In this regime, multimolecular gases begin to dissociate as they come into contact with the bow shock generated by the body. The type of gas selected begins to have an effect on the flow. Surface catalycity plays a role in the calculation of surface heating, meaning that the selection of the surface material also begins to have an effect on the flow. The lower border of this regime is where the first component of a gas mixture begins to dissociate in the stagnation point of a flow (Nitrogen~2000 K). The upper border of this regime is where the effects of ionization start to have an effect on the flow. Dissociation in chemistry and biochemistry is a general process in which complexes, molecules, or salts separate or split into smaller molecules, ions, or radicals, usually in a reversible manner. ...
Introduction The shock wave is one of several different ways in which a gas in a supersonic flow can be compressed. ...
In chemistry and biology, catalysis is the acceleration (increase in rate) of a chemical reaction by means of a substance, called a catalyst, that is itself not consumed by the overall reaction. ...
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Ionized gas In this regime the ionized electron population of the stagnated flow becomes significant, and the electrons must be modeled separately. Often the electron temperature is handled separately from the temperature of the remaining gas components. This region occurs for freestream velocities around 10-12 km/s. Gases in this region are modeled as non-radiating plasmas. ...
A Plasma lamp, illustrating some of the more complex phenomena of a plasma, including filamentation A solar coronal mass ejection blasts plasma throughout the solar system. ...
Radiation-dominated regime Above around 12 km/s, the heat transfer to a vehicle changes from being conductively dominated to radiatively dominated. The modeling of gases in this regime is split into two classes: - Optically thin: where the gas does not re-absorb radiation emitted from other parts of the gas
- Optically thick: where the radiation must be considered as a separate source of energy.
The modeling of optically thick gases is extremely difficult, since, due to the calculation of the radiation at each point, the computation load theoretically expands exponentially as the number of points considered.
See also Atmospheric reentry is the process by which vehicles that are outside the atmosphere of a planet can enter that atmosphere and reach the planetary surface intact. ...
X-43A with scramjet attached to the underside at Mach 7 A scramjet (supersonic combustion ramjet) is a variation of a ramjet where the flow of the air and combustion of the fuel air mixture through the engine happen at supersonic speeds. ...
The Skylon Spaceplane For other uses of the word Skylon, see Skylon (disambiguation) Skylon is a plausible design by top British rocket scientist Alan Bond for an aeroplane that would be able to fly into low earth orbit, and return, completely intact. ...
It has been suggested that this article or section be merged with Szabla. ...
External links - University of Queensland Centre for Hypersonics
- From President of India speech
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