The Aerodynamic and Propulsion Test Unit (APTU) is a blowdown facility designed for true temperature aerodynamic, propulsion, and material/structures testing. A vitiated air heater (VAH) provides the required temperature. Liquid oxygen is added in an oxygen mole fraction exists in the test medium. The facility is completely computer-controlled during a run, and very rapidly transitions in pressure and temperature (altitude changes) that can be accomplished at a fixed Mach number. The remote location of the facility plus the straight line ejector exhaust configuration, allows for unique test capabilities. For example, test article hardware separation, i.e. releasable model shrouds, is allowed. Certain types of ammunition/explosive (live-fire testing can be done. The facility is also sited for 10,000 pounds of Class 1.3 explosives.

A 22,000-cu ft high pressure air reservoir, which can be pressurized to 3,800 psia allows run duration from approximately 3 minutes to 12 minutes, depending on the free-jet nozzle selected and the altitude simulation required for the run. This air storage system is also the source for an annular air ejector, located in the exhaust duct, which is used to lower the test cell pressure to obtain various altitude simulations.

APTU Free-Jet Exhauster

Auxiliary air ejectors have been installed to augment the pumping capacity of the original air ejector. The chart shows the cell pressure obtainable with the original system, and the estimated improvement in performance with the auxiliary ejectors. The cell pressure is shown as a function of the total facility flow, i.e., the flow throughout the free-jet nozzle plus the flow from an engine test article. The curves also assume that the test article is not shrouded, so there is no momentum recovery from the test article or the free-jet nozzle. The indicated performance is greatly improved for an installation which allows the test article to be shrouded.


APTU Gaseous Oxidizer System

The gaseous oxidizer system has 2,100 cubic feet of storage capacity at 3,800 psia and ambient temperature. A pressure control valve allows the delivery pressure to be held constant at the desired level while a flow control valve allows the flow rate to be varied during a run. The chart shows system run times for a range of flow rates. Flow rates over 100 lbm/sec should be achievable with this system.

APTU Gaseous Hydrogen System

An ambient temperature gaseous hydrogen system has been added to the APTU complex to provide test article fuel. Six hydrogen trailers are connected to a manifold from which two lines enter the test cell. The chart shows the system run time as a function of hydrogen flow rate for various delivery pressures, assuming all six trailers are feeding a single delivery point. Valves in the manifold allow different combinations of trailers to feed the two supply lines. Thus two different delivery pointson a test article can be supplied at different pressures. The run time at each point will depend on the number of trailers serving the point, and the required delivery pressure.

Cooling Water Availability

Cooling water is supplied to the APTU complex from the AEDC pumping station through a 36-in diam main at 90 psia. This water can be used directly for low-pressure test article cooling requirements. If high-pressure cooling water is needed, the five pumps listed in the table can be used individually or in combination as necessary.



Office of Public Affairs, Arnold Engineering Development Center,

100 Kindel Drive, Suite B-213

Arnold Air Force Base, Tenn., 37389-2213 (931) 454-5586 DSN 340-5586

Current as of May 1998 Cleared for Public Release