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Arc-Heated Scramjet Test Facility

NASA Langley Research Center
The Langley Arc-Heated Scramjet Test Facility is part of the NASA Langley Scramjet Test Complex. The Facility is used to test complete subscale, scramjet component integration models at conditions simulating flight Mach numbers from 4.7 to 8.
Test Section and Performance
 Arc-Heated Scramjet Test Facility Characteristics
The Langley Arc-Heated Scramjet Test Facility (AHSTF) is used for tests of component integration models of airframe integrated scramjet engines at conditions experienced at flight Mach numbers,M, of 4.7 to 8.Results are used to assess the performance of the scramjet,to optimize the design of the components,and to optimize fueling schemes.

The arc heater and test section of the facility are located in room 111 of building 1247B. The facility is remotely operated with controls located in the adjacent room 110.The arc heater,facility nozzle,and test section are shown in the photograph on the front of this brochure. A cross-sectional view of the heater and an elevation view of the facility are shown in the figures.Typical models include the inlet,isolator,combustor,and a significant portion of the nozzle and are hydrogen and silane fueled. The flow at the exit of the facility nozzle simulates the flow entering a scramjet engine module in flight which has been processed by the forebody shock of the vehicle.The total enthalpy of the flight condition is achieved by electrically heating the air with a Linde arc heater.

The AHSTF range of operation is shown by the chart of standard test conditions and a Mach number/altitude map. The map shows simulation envelopes for the Mach number 4.7 and the Mach number 6 nozzles. Higher Mach number simulation is achieved by increasing the stagnation enthalpy of the flow. For any flight Mach number there is an oblique shock that will reduce the Mach number to that of the facility nozzle. The turning angle (a) in the figure indicates the turning angle of the oblique shock that reduces the simulated flight Mach number to the facility nozzle Mach number. Thus, scramjet tests in the facility at stagnation enthalpies greater than that corresponding to the nozzle exit Mach number represent various degrees of aircraft forebody precompression.

The normal test schedule of theAHSTF is two test days per week with four to six runs per test day. Run times normally range from 30 sec at flight Mach number of 8 simulated conditions to 60 sec at flight Mach number of 4.7 simulated conditions.
Simulated flight Mach number 4.7 to 8
Flight Reynolds number,ft-1 3.5x104 to 2.2x106

Nozzle exit area,in
Mach number of 4.7 11.17 x 11.17
Mach number of 6 10.89 x 10.89

Test Medium
dried air

Heater
Total pressure limit,psia 675
Total temperature,degrees R 2000 to 5200


AHSTF Heater
Data Acquisition and Processing
Data are acquired primarily through a data amplifier/multiplexer with 192 general purpose analog channels and 16 digital channels and a pressure scanner with up to 448 channels.Approximately 60 analog channels and the 16 digital channels are dedicated to facility parameters.Pressure scanner transducer modules are available with various pressure ranges.A 6-component force balance that can support test articles weighing up to 1500 lb is available for measuring forces and moments on test articles.The data acquisition system is controlled with a microcomputer that interfaces with a UNIX workstation which is used for posttest data analysis. A secure operating mode is provided for classified projects. 		Facilities Available to Users
Models can be prepared in either the test room or an adjoining shop. Two full time facility technicians are available to assist in model preparation.

Safety and Design Criteria
Langley?s LHB 1710.15Wind Tunnel Model System Criteria is used only as a guide-line for model design and fabrication of test articles. Test articles are typically considered expendable. Failure of a test article will not result in catastrophic damage to the facility or place any personnel at risk. Specific questions should be addressed to the AHSTF Safety Head.
Model Supports
Test articles are typically provided with a support structure that interfaces with the facility balance housing. Changes in horizontal position or angular orientation are accommodated in the test article support structure. The facility hardware provides for adjustment in the vertical direction only. Test articles are mounted in the test section so that they ingest the free jet flow from the facility nozzle.
Mach Number/Altitude Map
 Test Conditions

Test Gas
Type of Testing
 Test Request Procedures

NASA SXPE model at Arc-Heated Scramjet Test Facility. 		The AHSTF has been in operation for scramjet testing since 1976. Scramjet engines tested in this facility include the NASA 3-Strut; NASA Parametric; Rocketdyne A,A1,A2, and A2+; Pratt and Whitney C; NASP SX-20; and the NASP SXPE. Currently the AHSTF is testing the Hyper-X DFX engine. Since December 1976, over 1300 scramjet tests have been conducted in the AHSTF. The first step of the test process is to submit a test request form. The form can be filled out electronically or printed for mailing at the NASA Langley aero Compass website. A posttest questionnaire is also available at this site. Our customers are encouraged to provide feedback to the facility for our continuous improvement process.
Test Techniques
 Test Medium
The Langley 5000 psig air system provides main air at flow rates of 0.50 to 2.20 lbm per sec to the arc heater. Power to the arc heater is provided by 2 10-MW direct-current power supplies connected in series with stabilizing ballast resistors. The arc operates at up to 13 MW and can deliver up to approximately 6.5 MW to the air. The air is heated to a stagnation enthalpy of approximately 3000 Btu per lbm and at stagnation pressures up to 660 psia. The air from the heater enters a plenum chamber where it is diluted with bypass air to achieve the required total enthalpy,usually between 500 and 1600 Btu per lbm. The bypass air,also from the 5000-psig air system,is controlled to flow rates of approximately 1 to 10 lbm per sec. The arc heater and nozzle throat sections are cooled with de-ionized water which can be supplied at pressures up to 1400 psig.

From the plenum,the air enters the facility nozzle. The facility has available two fixed geometry contoured nozzles with square cross sections: a Mach number 4.7 nozzle with an 11.17-in2 exit and a Mach number 6.0 		nozzle with a 10.89-in2 exit.The installed nozzle produces a free jet into a 4-ft diameter test section,which is 11-ft in length.

The test gas and scramjet exhaust gases are diffused to subsonic velocities in a 33.5-ft long,4-ft diameter, straight-pipe diffuser prior to entering a subsonic diffuser. A 100-ft diameter vacuum sphere,which can be evacuated to 0.02 psia,is used to maintain low test section pressures.

Models are fueled with hydrogen (at ambient temperature), which is stored in a 31.46-ft3 bottle with a usual fill pressure of 1200 psig. The pressure is regulated to a maximum of 625 psig in two facility manifolds that feed 12 choked venturis,which in turn feed the model fuel manifolds. A 20-percent silane and 80-percent hydrogen mixture (by volume) is supplied from 4 K-size cylinders at 2400 psia for use as an igniter and pilot gas to aid in the combustion of the hydrogen fuel. The silane mixture is regulated to a maximum of 650 psig and fed through two choked venturis. 		The test medium at the AHSTF is dried air heated in an electric arc.Such flows are contaminated by the copper and copper oxides that erode from the electrode. Levels have not been measured,but evidence indicates that it is in the form of small particles that have a wearing effect on test articles but do not affect the combustion processes significantly.Varying levels of nitrogen oxides are also produced in the arc and by stagnating the high enthalpy flow. Calculated test gas compositions for the standard operating conditions are tabulated below. The calculations employed finite-rate chemistry throughout the arc heater,plenum chamber,and the facility nozzles. The levels of NO in the test flow,verified by measure-ment, range from 0.0111 mole fraction at Minfinity = 4.7 to 0.0306 mole fraction at Minfinity = 8. Oxygen deficits due to the formation of NO are not replenished,and the facility operates at Minfinity = 4.7 with 0.2034 oxygen mole fraction and at Minfinity = 8 with 0.1940 oxygen mole fraction.
Document Version 1.0
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The use of trademarks or names of manufacturers in this report is for accurate reporting and does not constitute an official endorsement, either expressed or implied, of such products or manufacturers by the National Aeronautics and Space Administration.
For more information contact:
The Arc-Heated Scramjet Test Facility Manager -- NASA Langley Research Center -- Hampton, Virginia 23681-2199
phone: 757 ° 864 ° 6334 | fax: 757 ° 864 ° 6243 | e-mail: wte+fm_ahstf@larc.nasa.gov
NASA Official Responsible For Content:
Pete Jacobs		 Page Curator: CONITS Development Team Date Last Updated:11/17/2005