Hypersonic wind tunnel

Hypersonic wind tunnel

A hypersonic wind tunnel is designed to generate a hypersonic flow field in the working section. The speed of these tunnels vary from Mach 5 to 15. As with supersonic wind tunnels, these types of tunnels must run intermittently with very high pressure ratios when initializing.Since the temperature drops with the expanding flow, the air inside has the chance of becoming liquefied. For that reason, preheating is particularly critical (the nozzle may require cooling). High pressure and temperature ratios can be produced with a shock tube.

Technological problems

There are several technological problems in designing and constructing a hyper-velocity wind tunnel:
*supply of high temperatures and pressures for times long enough to perform a measurement
*reproduction of equilibrium conditions
*structural damage produced by over-heating
*fast instrumentation
*power requirements to run the tunnelSimulations of a flow at 5.5 km/s, 45 km altitude would require tunnel temperatures of as much as 9000 K, and a pressure of 3 GPa (see ).

Hot shot wind tunnel

One form of HWT is known as a Gun Tunnel or hot shot tunnel (up to "M"=27), which can be used for analysis of flows past ballistic missiles, space vehicles in atmospheric entry, and plasma physics or heat transfer at high temperatures. It runs intermittently, like other high speed tunnels, but has a very low running time (less than a second).The method of operation is based on a high temperature and pressurized gas (air or nitrogen) produced in an arc-chamber, and a near-vacuum in the remaining part of the tunnel. The arc-chamber can reach several MPa, while pressures in the vacuum chamber can be as low as 0.1 Pa. This means that the pressure ratios of these tunnels are in the order of 10 million. Also, the temperatures of the hot gas are up to 5000 K. The arc chamber is mounted in the gun barrel. The high pressure gas is separated by the vacuum by a diaphragm that breaks down as its resistance is exceeded.

Prior to a test run commencing, a membrane separates the compressed air from the gun barrel breech. A rifle (or similar) is used to rupture the membrane. Compressed air rushes into the breech of the gun barrel, forcing a small projectile to accelerate rapidly down the barrel. Although the projectile is prevented from leaving the barrel, the air in front of the projectile emerges at hypersonic velocity into the working section. Naturally the duration of the test is extremely brief, so high speed instrumentation is required to get any meaningful data.

ee also

* Wind tunnel
* Low speed wind tunnel
* High speed wind tunnel
* Supersonic wind tunnel
* Ludwieg tube
* Shock tube
* Hypersonic
* NASA

External links

* [http://www.vki.ac.be/facilities/pdf/longshot.pdf Hot Shot Wind Tunnel] at the Von Karman Institute for Fluid Dynamics


Wikimedia Foundation. 2010.

Игры ⚽ Нужен реферат?

Look at other dictionaries:

  • Wind tunnel — A wind tunnel is a research tool developed to assist with studying the effects of air moving over or around solid objects.Ways that wind speed and flow are measured in wind tunnels: * Threads can be attached to the surface of study objects to… …   Wikipedia

  • wind tunnel — /wind/, Aeron. a tubular chamber or structure in which a steady current of air can be maintained at a controlled velocity, equipped with devices for measuring and recording forces and moments on scale models of complete aircraft or of their parts …   Universalium

  • Supersonic wind tunnel — A supersonic wind tunnel is a wind tunnel that produces supersonic speeds (1.2 …   Wikipedia

  • Subsonic and transonic wind tunnel — ubsonic tunnelLow speed wind tunnels are used for operations at very low mach number, with speeds in the test section up to 400 km/h ( 100 m/s, M = 0.3). They are of open return type ( losses. Open wind tunnelThe working principle is based on the …   Wikipedia

  • wind tunnel — A tubelike structure or passage, sometimes continuous, which together with its adjuncts (such as a fan), produces a high speed movement of air or other gas. Objects such as engines or aircraft, airfoils, rockets (or models of these objects), etc …   Aviation dictionary

  • hypersonic — adjective Etymology: International Scientific Vocabulary Date: 1946 1. of or relating to speed five or more times that of sound in air compare sonic 2. moving, capable of moving, or utilizing air currents that move at hypersonic speed …   New Collegiate Dictionary

  • Atmospheric reentry — refers to the movement of human made or natural objects as they enter the atmosphere of a planet from outer space, in the case of Earth from an altitude above the edge of space. This article primarily addresses the process of controlled reentry… …   Wikipedia

  • Naval Ordnance Laboratory — The Naval Ordnance Laboratory (NOL), now disestablished, formerly located in White Oak, Maryland was the site of considerable work that had practical impact upon world technology. The White Oak site of NOL has now been taken over by the Food and… …   Wikipedia

  • Shock tube — A shock tube is a device used primarily to study gas phase combustion reactions. Shock tubes (and related shock tunnels) can also be used to study aerodynamic flow under a wide range of temperatures and pressures that are difficult to obtain in… …   Wikipedia

  • Syvertson — Clarence A. Sy Syvertson is the retired Center Director of the Ames Research Center of the National Aeronautics and Space Administration, located at Moffett Field, California. Syvertson was born in Minneapolis, Minnesota in 1926. He graduated… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”