An impulse facility is a testing facility that relies on rapid release of stored

energy In physics, energy (from Ancient Greek: ἐνέργεια, ''enérgeia'', “activity”) is the quantitative property that is transferred to a body or to a physical system, recognizable in the performance of work and in the form of hea ...

to generate a short period of high

enthalpy Enthalpy , a property of a thermodynamic system, is the sum of the system's internal energy and the product of its pressure and volume. It is a state function used in many measurements in chemical, biological, and physical systems at a constant ...

test conditions for testing of

aerodynamic Aerodynamics, from grc, ἀήρ ''aero'' (air) + grc, δυναμική (dynamics), is the study of the motion of air, particularly when affected by a solid object, such as an airplane wing. It involves topics covered in the field of fluid dyn ...

flow, aerodynamic heating and atmospheric reentry,

combustion Combustion, or burning, is a high-temperature exothermic redox chemical reaction between a fuel (the reductant) and an oxidant, usually atmospheric oxygen, that produces oxidized, often gaseous products, in a mixture termed as smoke. Combus ...

chemical kinetics Chemical kinetics, also known as reaction kinetics, is the branch of physical chemistry that is concerned with understanding the rates of chemical reactions. It is to be contrasted with chemical thermodynamics, which deals with the direction in ...

, ballistics, and other effects. The rapid release of energy can result in very high instantaneous energy release rates even though the total energy released is modest. The use of an impulse facility can allow testing of violently energetic phenomena generating temperatures and pressures that no known materials could withstand in steady state. This effect also produces short test times, however, with some types of tests in these facilities lasting less than 100

microsecond A microsecond is a unit of time in the International System of Units (SI) equal to one millionth (0.000001 or 10−6 or ) of a second. Its symbol is μs, sometimes simplified to us when Unicode is not available. A microsecond is equal to 1000 ...

s. Impulse facilities are a special case of blow down facilities where an energy storage mechanism is charged over a period of time and then released to initiate a test and must be charged again before the next test. This contrasts with continuous facilities such as

wind tunnel Wind tunnels are large tubes with air blowing through them which are used to replicate the interaction between air and an object flying through the air or moving along the ground. Researchers use wind tunnels to learn more about how an aircraft ...

s that may run continuously. Examples of impulse facilities are the

shock tube : ''For the pyrotechnic initiator, see Shock tube detonator'' The shock tube is an instrument used to replicate and direct blast waves at a sensor or a model in order to simulate actual explosions and their effects, usually on a smaller scale. ...

, the

shock tunnel In aeronautics, expansion and shock tunnels are aerodynamic testing facilities with a specific interest in high speeds and high temperature testing. Shock tunnels use steady flow nozzle expansion whereas expansion tunnels use unsteady expansion wit ...

, the expansion tube, the

expansion tunnel In aeronautics, expansion and shock tunnels are aerodynamic testing facilities with a specific interest in high speeds and high temperature testing. Shock tunnels use steady flow nozzle expansion whereas expansion tunnels use unsteady expansion wit ...

, and the Ludwieg tube.

References

Engineering equipment {{engineering-stub