Hypersonic_Wind_Tunnel_FINAL.DOCX

U.S. Naval Research Laboratory Hypersonic Wind Tunnel System CLIN 0001 Hypersonic Wind Tunnel Specifications

1. Acronyms, Abbreviations, Nomenclature, and Units

2. Overview

The U.S. Naval Research Laboratory (NRL) is procuring a hypersonic blowdown wind tunnel with continuously variable Mach number between 2.0 or lower and 6.0 or greater with dynamic, real-time variation of Mach number and flight dynamic pressure. The desired test section dimension is nominally 12 inches high by 12 inches wide, with an operating range for dynamic pressure between 10 kPa or lower to 100 kPa or higher. The desired test duration is nominally 20 seconds or greater at Mach 3 and 100 kPa with the option to expand the air supply.

2.1. Approach

The technical approach consists of building a conventional variable-speed, cold, blow-down hypersonic wind tunnel similar to that described in Ref [1] and characterized in Ref [2], with the nozzle block travel range spanning at least Mach 2 to Mach 6.

2.2. Configuration Overview

The proposed facility shall be in a blowdown configuration, as outlined in Figure 1, wherein a compressor system dries and compresses clean, ambient air, and stores the high-pressure, clean, dry supply air in a bank of high-pressure tanks sharing a common manifold to the stagnation chamber, and controlled with a shut-off valve and a flow regulator. When the shut-off valve is open, the flow regulator upstream of the stagnation chamber shall consistently control the stagnation chamber pressure and mass flow rate based on the test section operating point.

Figure 1. Blowdown tunnel component flow chart

The stagnation chamber, tunnel assembly (comprised of the nozzle, test section and associated diagnostics), and the diffuser are included in CLIN 0001 Hypersonic Wind Tunnel. The compressor system and regulators are included in CLIN 0002 Air Compressor and Regulators. The storage tanks, valves, and interconnecting supply piping between all systems are included in CLIN 0003 Air Storage Tanks and Piping.

The components of the hypersonic wind tunnel system are described in the following sections along with their features and specifications.

3. Hypersonic Wind Tunnel Components

3.1. General Requirements

3.1.1. The minimum service pressure for all components exposed to internal flow shall be at least 200 psig.

3.1.2. The minimum service temperature for all components exposed to internal flow shall be at least 60 C.

3.1.3. The assemblies shall use minimal permanent fastening wherever possible in order to enable maintenance and future upgrades or modification.

3.1.4. All custom software shall be updateable and configurable by the Government.

3.1.5. The hypersonic wind tunnel system, data acquisition system, and all major system components shall include user instructions, maintenance, and troubleshooting documentation.

3.2. Stagnation Chamber

3.2.1. The stagnation chamber shall be rated to a working pressure of at least 200 psig with appropriate factors of safety at 60 C.

3.2.2. The stagnation chamber shall be designed to leak before burst.

3.2.3. The stagnation chamber shall include turbulence-reducing screens, fine honeycomb structure, or similar devices in order to make the incoming flow velocity profile more uniform.

3.2.4. The stagnation chamber shall include internal ducting that smoothly transitions from the circular cross-section of the stagnation chamber to the rectangular cross section of the tunnel inlet.

3.2.5. The interface on the inlet side of the stagnation chamber shall be an ANSI B16.5 Class 300 flange for NPS 12 pipe

3.2.6. The pressure of the air supply to the tunnel inlet shall not vary by more than ±1%.

Variation in supply pressure corresponds approximately to variation in density altitude.

3.2.7. The hypersonic wind tunnel system shall take no longer than 3 seconds to reach steady state operation.

3.3. Tunnel Assembly

3.3.1. The tunnel nozzle contours shall consist of one moveable nozzle block as detailed in Ref [1] and depicted in Figure 2.

Figure 2. UMich Mach 1.3 – 4 Adjustable Supersonic Wind Tunnel Contour

3.3.2. The adjustable lower nozzle block shall be capable of a linear positioning rate of at least 2.2 inches per second during testing.

Intent is to dynamically simulate acceleration and deceleration, or to enable efficient sweep through Mach numbers. Slew rate of 0.1 Mach per second also corresponds to an acceleration of approximately 1g.

3.3.3. The test section shall conform to the profile detailed in Ref [1] and be at least 12 inches high by 12 inches wide.

3.3.4. The Offeror shall state the design minimum high-pressure operation in equivalent dynamic pressure of the test section.

3.3.5. The Offeror shall state the design maximum low-pressure operation in equivalent dynamic pressure of the test section.

3.3.6. The test section shall be accessible for model replacement by either an access door, window removal, or diffuser removal.

3.3.7. The test section window material shall be optical-quality glass that can pass infrared wavelengths for thermal imaging.

3.3.8. The test section window shall be at least 12 inches high by 24 inches long.

3.3.9. The Offeror shall include and detail a 12 inch diameter Schlieren flow visualization system.

3.3.10. The nozzle shall include corrections for boundary layer growth in order to maintain consistent Mach number despite wall friction, per Ref [1].

3.4. Diffuser

3.4.1. Downstream of the test section, the diffuser or downstream ducting shall include noise attenuation to limit noise to 120 dB at 100 kPa dynamic pressure at a distance of 10 feet.

3.4.2. The interface on the outlet side of the diffuser shall be an ANSI B16.5 Class 150 flange for NPS 24 pipe.

3.5. Model Positioning System

3.5.1. The model positioning system shall hold the test model at the nominal center of the test section.

3.5.2. The model positioning system shall be capable of pivoting in the pitch and yaw directions.

3.5.3. The model positioning system shall be capable of traversing a pitch angle of -5 degrees to +10 degrees, referenced from the horizontal symmetry plane of the tunnel.

3.5.4. The model positioning system shall be capable of traversing a yaw angle of -10 degrees to +10 degrees, referenced from the vertical symmetry plane of the tunnel.

3.5.5. The model positioning system shall be capable of traversing the pitch range at a slew rate of 1 degree per second.

3.5.6. The model positioning system shall be capable of traversing the yaw range at a slew rate of 1 degree per second.

3.6. Control System

3.6.1. The Control System shall be based on Matlab, LabView, Fortran, or a C language in order to facilitate future modification and customization.

3.6.2. The Control System shall include a Graphical User Interface (GUI) for user input conditions.

3.6.3. The Control System shall allow for dynamic variation of control inputs for model position and orientation and test section flow conditions by the user.

3.6.4. The Control System shall allow for dynamic variation of control inputs for model position and orientation and test section flow conditions by script.

4. Data Acquisition

4.1. The Data Acquisition System (DAS) shall be based on Matlab or LabView in order to facilitate future modification and customization.

4.2. Telemetry

4.2.1. The DAS system shall be able to measure and store the static temperature in the stagnation chamber.

4.2.2. The DAS system shall be able to measure and store the static temperature in the test section.

4.2.3. The DAS system shall measure and store temperature at 1 Hz.

4.2.4. The DAS system shall be able to measure and store the static pressure in the stagnation chamber.

4.2.5. The DAS system shall be able to measure and store the static pressure in the test section.

4.2.6. The DAS system shall measure and store forces at 100 Hz.

4.2.7. The DAS system shall be able to measure and store forces in the normal, axial, and lateral directions

4.2.8. The DAS system shall measure and store forces at 100 Hz.

4.2.9. The force measurement ranges shall be as follows:

Normal: 1 N to 1500 N Axial: 1 N to 500 N Lateral: 1 N to 1500 N

4.2.10. The resolution for the force measurements shall be 0.01N or better.

5. Performance

5.1. Performance Envelopes

5.1.1. The Offeror shall provide flight envelope contour plots for the following variables in an empty test section in consideration of limitations imposed by temperature and liquefaction, air mass flow rate, and viscous choking of the nozzle:

Density Altitude and Mach Number Reynolds Number and Mach Number Dynamic Pressure and Mach Number

6. Installation

6.1. The Offeror shall specify all necessary hardware, electrical, and data interface information required for installation of the hypersonic wind tunnel system.

6.2. The Offeror shall install the hypersonic wind tunnel system and associated hardware at the NRL, and integrate the system with the Government-provided interfaces.

6.3. The Offeror shall provide system tuning for optimal operation across the operational range of the purchased system.

6.4. The Offeror shall provide training for Government personnel for operation of the hypersonic wind tunnel system, its control system, data acquisition system, and best practices for experimental methods.

6.5. The Offeror shall provide options for continued support on an hourly consulting basis.

7. Warranty

7.1. The Offeror shall include a warranty on workmanship and functional operation for at least one year on all equipment provided.

8. Evaluation Factors

The key evaluation factors are as follows:

8.1. Technical Solution

8.2. Unique capability

8.3. Proposal Cost and Value to the NRL

8.4. Performance Risk Analysis

8.5. Past Performance

8.6. Key Personnel

9. Intellectual Property

9.1. The ownership of intellectual property to include proprietary design information, methods, suppliers, materials, etc. must be stated by the Offeror or proposed as specific pricing conditions.

APPENDIX

A. References

[1] Amik, J.L., Liepman, H.P., Reynolds, T.H., “Development of a Variable Mach Number Sliding Block Nozzle and Evaluation in the Mach 1.3 to 4.0 Range,” WADC TR-55-88, 1955.

[2] Pope, A., Goin, K.L., High Speed Wind Tunnel Testing, 2nd ed., Krieger Pub. Co., 1978. ISBN 9780471694021

[3] Jesse R. Maxwell and Gabriel B. Goodwin. "Flow Quality Numerical Characterization for Cold Adjustable Supersonic Wind Tunnel", 33rd AIAA Aerodynamic Measurement Technology and Ground Testing Conference, AIAA AVIATION Forum, (AIAA 2017-4318) https://doi.org/10.2514/6.2017-4318

[4] Jesse R. Maxwell. "Operational Range and Flow Quality of Cold Hypersonic Wind Tunnel", 33rd AIAA Aerodynamic Measurement Technology and Ground Testing Conference, AIAA AVIATION Forum, (AIAA 2017-3983) https://doi.org/10.2514/6.2017-3983

[5] Jesse R. Maxwell. "Scaling Effects on Flow Quality for a Cold Adjustable Supersonic Wind Tunnel", 33rd AIAA Aerodynamic Measurement Technology and Ground Testing Conference, AIAA AVIATION Forum, (AIAA 2017-4317) https://doi.org/10.2514/6.2017-4317

[6] Maxwell J. Design and Performance of a Hypersonic Wind Tunnel. ASME. Fluids Engineering Division Summer Meeting, Volume 1B, doi:10.1115/FEDSM2017-69439.

[7] Jesse R. Maxwell. "Dynamic Depletion and Test Section Conditions Model for Blow-Down Supersonic Wind Tunnel", 2018 AIAA Aerospace Sciences Meeting, AIAA SciTech Forum, (AIAA 2018-0628) https://doi.org/10.2514/6.2018-0628

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