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Hypersonic Wake Detection with High Enthalpy Capabilities



OBJECTIVE: Develop a hypersonic vehicle tracking system based on analysis of the wake turbulence and chemiluminescence.

DESCRIPTION: The distribution of observable markers in hypersonic wakes is the result of a complex interaction of body shape, chemical kinetics, and laminar-turbulent transition mechanisms. At hypersonic speeds in a gas, electrons and radiating species are generated by viscous heating that are entrained into the wake and are responsible for observable effects up to distances of hundreds or even thousands of body diameters. Clearly an understanding of the radiation signature of reentry vehicles is of fundamental importance to high-speed-flight research. During a brief period in the early 1960s, a number of experiments were conducted on this problem that involved performing both velocity measurements to characterize the turbulence development in the wake and spectroscopic techniques to identify the chemical kinetics of reacting species [Refs 1, 2, 3, 4, 5].A general conclusion from this early body of work was that theoretical models were insufficient to adequately predict the structure of the wake and additional experiments were required. Improving the understanding of the laminar-to-turbulence transition, separation dynamics just behind the body, and turbulence statistics and structure in the wake was needed. Uncertainty in the estimations of enthalpy made it difficult to predict the temperature in the wake, which affects kinetics and generation of reacting species, crucial to the complete characterization of a hypersonic wake. A principle limitation was the unavailability of point-wise sensors with high-bandwidth sensitivity to mass-flux, temperature, and gas species with the required robustness and small measurement volumes.Optical diagnostic tools do not provide point-wise capability and often involve path integration and are limited by the need for optical access. A new sensor is required that overcomes these limitations while providing both high bandwidth velocity and species detection capabilities. This sensor should be able to survive in harsh conditions involving exposed plasmas, an environment at temperatures of 1100 °C or greater, and high turbulence levels of 10% or greater in particulate-laden flows. The sensor should not require optical access, and should provide good spatial resolution with measurement volumes under 0.25 cu cm.Work produced in Phase II may become classified. Note: The prospective contractor(s) must be U.S. owned and operated with no foreign influence as defined by DoD 5220.22-M, National Industrial Security Program Operating Manual, unless acceptable mitigating procedures can and have been implemented and approved by the Defense Counterintelligence and Security Agency (DCSA). The selected contractor and/or subcontractor must be able to acquire and maintain a secret level facility and Personnel Security Clearances, in order to perform on advanced phases of this project as set forth by DCSA and SSP in order to gain access to classified information pertaining to the national defense of the United States and its allies; this will be an inherent requirement. The selected company will be required to safeguard classified material IAW DoD 5220.22-M during the advanced phases of this contract.

PHASE I: Develop a concept for velocity and gas mixture composition sensing capable of withstanding 1100°C environments. Demonstrate the feasibility of the proposed sensor type and the packaging approach suitable to satellite payloads less than 1000 cu cm. Describe the manufacturing feasibility of the sensor and packaging necessary for commercialization efforts. Experimentally demonstrate feasibility of the proposed sensor at a laboratory scale at hypersonic Mach numbers. The Phase I Option, if exercised, will include the initial design specifications and capabilities description to build a prototype solution in Phase II. Develop a Phase II plan.

PHASE II: Fabricate and characterize several full prototype devices in a low enthalpy hypersonic quiet tunnel and high enthalpy high Mach number flow field facilities. Prepare a Phase III development plan to transition the technology for Navy use and potential commercial use.It is probable that the work under this effort will be classified under Phase II (see Description section for details).

PHASE III: Support the Navy in transitioning the technology to Navy use. Conduct necessary qualification testing of the device to merit further investment and consideration for military hypersonic vehicle platforms. Work together with original equipment manufacturer (OEM) to develop a business plan and necessary IP, and seek necessary investment to support the product/process/service for the OEM military provider. The use of chemiluminescence has potential applications in welding and plasma processing where the environments do not support physical interaction with the objects of interest.

KEYWORDS: Reentry Vehicles, Chemiluminescence, Hypersonic, Wake Turbulence, High Enthalpy, Laminar-turbulent Transition


1. Bayes, K., and Kistiakowsky, G.B. “On the Mechanism of the Lewis-Rayleigh Nitrogen Afterglow.” Chemical Physics, 32, 4, March 1960, pp. 992-1000. 2. Hundley, R. “Air Radiation From Nonequilibrium Wakes of Blunt Hypersonic Reentry Vehicles.” Memorandum RM-4071-ARPA, June 1964. 3. Lees, L. “Hypersonic Wakes and Trails.” AIAA Journal 2, 3, 1964, pp. 417-428.”4. Levensteins, Z., and Krumins, M. “Aerodynamic Characteristics of Hypersonic Wakes.”, AIAA Journal 5, 9, 1967, pp. 1596-1602. 5. Tanaka, Y., Innes, F., Jursa, A., and Nakamura, M. “Absorption Spectra of the Pink and Lweis-Rayleigh Afterglows of Nitrogen in the Vacuum-uv Region.” J. Chem. Phys. 42, 4, 1965, pp. 1183-1198.

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