Sensor System for Time-Resolved Temperature Measurements in High-Temperature/High-Velocity Exhaust Plumes

Navy STTR 23.A - Topic N23A-T005
NAVAIR - Naval Air Systems Command
Pre-release 1/11/23   Opens to accept proposals 2/08/23   Closes 3/08/23 12:00pm ET    [ View Q&A ]

N23A-T005   TITLE: Sensor System for Time-Resolved Temperature Measurements in High-Temperature/High-Velocity Exhaust Plumes

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): General Warfighting Requirements (GWR)

OBJECTIVE: Develop a time-resolved sensor system for measuring gas dynamic and compositional characteristics of high-temperature/high-velocity engine exhaust plumes.

DESCRIPTION: Time-resolved measurements in high-temperature and high-velocity exhaust plumes are necessary to better understand transient phenomena including startup/shut down, combustion instabilities, and flow nonuniformity. Measurement parameters of interest in exhaust plumes include temperature, pressure, velocity, combustion efficiency, and gas composition.

High-temperature, high-velocity exhaust plumes present a uniquely challenging measurement environment. Wetted sensors, such as thermocouples and pressure transducers, degrade rapidly in reactive, particle-laden, high-temperature, high-velocity plume flows, emphasizing a need for noninvasive measurement approaches. Similarly, noninvasive optical techniques are hampered by low-transmission, large-density gradients, and high-thermal, spontaneous emission in hot, fast, particle-laden flows. An innovative sensor system is desired for measurements in high-temperature and high-velocity exhaust plumes. Extending existing measurement technologies to full-scale engines requires improved strategies in sensor survivability, overcoming poor signal-to-noise ratio, and the extreme acoustic and vibratory environment in close proximity to the exhaust plume.

Key sensor system parameters should include, but not be limited to the following:

1. Measuring temperature is of primary interest. Additional measurement parameters of interest include pressure, velocity, combustion efficiency, and gas composition. Desired speciation of composition measurements include unburned fuel components, intermediate fuel-cracking products, and final products (CO, CO2, H2O, NO, NO2).

2. Temperature measurement accuracy must be better than +/- 5%.

3. Sensor must provide, spatially-resolved point or line-averaged measurements to a resolution of at least 1 mm or smaller. Two-dimensional maps of measurement parameters are also of interest.

4. Minimum sensor bandwidth must exceed 1 kHz. Increased bandwidth up to 100 kHz is preferred.

5. The operational envelope for the sensor must span temperatures from 500�3,000 K (227�2727 �C).

6. Optical sensors are of interest to provide noninvasive measurements that do not perturb plume characteristics. Optical sensors must be capable of performing measurements in particle-laden, highly emissive flows.

7. Sensor lifetime for high-temperature, high-velocity exhaust plume measurements must exceed 1,000 hr.


PHASE I: Develop a concept and determine the feasibility of a sensor system for time-resolved measurements in high-temperature, high-velocity exhaust plumes with the ideal goal of providing greater than 1 kHz measurement bandwidth. Ensure that the concept sensor provides point- or line-averaged measurements of temperature over the range of 500 to 3,000 K (227�2727 �C).

Additional measurement parameters�including pressure, velocity, combustion efficiency, and composition�are of interest, but not required, in Phase I. Noninvasive optical measurement approaches are desirable, but must be able to operate in flows with high-particulate loads (low transmission) and high emission. Phase I should include (a) benchtop testing and validation of sensor concept and accuracy in controlled high-temperature gas environment, (b) designs for construction of field-deployable sensor prototype, and (c) detailed prototype plans to be developed under Phase II.

PHASE II: Develop, demonstrate, and validate a prototype sensor. Improve upon the performance, reliability, and usability of the sensor. Perform field demonstrations, which will guide sensor improvements. Desired improvements include (a) measurement bandwidth in excess of 10 kHz, (b) temperature measurement accuracy better than +/- 5%, (c) measurements at multiple locations within a plume, including close proximity to the nozzle exhaust, and (d) increased capability to handle all relevant engine operating conditions. Include the extension of the sensor prototype to include additional measurement parameters such as pressure, velocity, combustion efficiency, and/or composition. Include (a) revision of the sensor design to improve performance, reliability, and usability; (b) successful demonstration of temperature measurements using the second-generation prototype in high-temperature/velocity exhaust plume; (c) successful demonstration of additional measurement parameters using the second-generation prototype in high-temperature, high-velocity exhaust plume; and (d) delivery and initial testing of the sensor prototype.

PHASE III DUAL USE APPLICATIONS: Complete final testing and transition the technology for Navy use. Accurate time-resolved measurements of aircraft engine, rocket, and other plumes could steer development of commercial propulsion systems and modeling tools used in their development.


1.       Peng, W. Y., Cassady, S., Strand, C. L., Goldenstein, C. S., Spearrin, R. M., Brophy, C. M., Jeffries, J. B., & Hanson, R. K. (2019). Single-ended mid-infrared laser-absorption sensor for time-resolved measurements of water concentration and temperature within the annulus of a rotating detonation engine. Proceedings of the Combustion Institute, 37(2) 1435-1443. Elsevier.

2.       Goldenstein, C. S., Spearrin, R. M., Jeffries, J. B., & Hanson, R. K. (2017). Infrared laser-absorption sensing for combustion gases. Progress in Energy Combustion Science, 60, 132-176.

3.       Goldenstein, C. S., Almodovar, C. A., Jeffries, J. B., Hanson, R. K., & Brophy, C. M. (2014). High-bandwidth scanned-wavelength-modulation spectroscopy sensors for temperature and H2O in a rotating detonation engine. Measurement Science and Technology, 25(10), 105104.

4.       Sun, K., Sur, R., Chao, X., Jeffries, J. B., Hanson, R. K., Pummill, R. J., & Whitty, K. J. (2013). TDL absorption sensors for gas temperature and concentrations in a high-pressure entrained-flow coal gasifier. Proceedings of the Combustion Institute, 34(2), 3593-3601.

5.       Hanson, R. K. (2011). Applications of quantitative laser sensors to kinetics, propulsion and practical energy systems. Proceedings of the Combustion Institute, 33(1), 1-40.

6.       Schäfer, K., Heland, J., Lister, D. H., Wilson, C. W., Howes, R. J., Falk, R. S., Lindermeir, E., Birk, M., Wagner, G., Haschberger, P., Bernard, M., Legras, O., Wiesen, P., Kurtenbach, R., Brockmann, K. J., Kriesche, V., Hilton, M., Bishop, G., Clarke, R., � Vally, J. (2000). Nonintrusive optical measurements of aircraft engine exhaust emissions and comparison with standard intrusive techniques. Applied Optics, 39(3), 441-455.

7.       Ihme, M., 2017. Combustion and engine-core noise. Annual Review of Fluid Mechanics, 49, pp.277-310.

8.       Brès Guillaume A. and Lele Sanjiva K. 2019. Modelling of jet noise: a perspective from large-eddy simulations. Phil. Trans. R. Soc. A.

9.       Cavalieri, A. V. G., Jordan, P., and Lesshafft, L. (March 13, 2019). "Wave-Packet Models for Jet Dynamics and Sound Radiation." ASME. Appl. Mech. Rev. March 2019; 71(2): 020802.


KEYWORDS: High Temperature Sensor; Temperature Measurement; Time-Resolved; Plume Measurements; Combustion Measurements; Gas Composition Measurement


The Navy Topic above is an "unofficial" copy from the Navy Topics in the DoD 23.A STTR BAA. Please see the official DoD Topic website at for any updates.

The DoD issued its Navy 23.A STTR Topics pre-release on January 11, 2023 which opens to receive proposals on February 8, 2023, and closes March 8, 2023 (12:00pm ET).

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Topic Q & A

1/16/23  Q. 1. What size engines are of interest?

2. Can the types and distributions of the expected particulates be described for �particle-laden� exhausts?

3. What is the desired spatial resolution?

4. From the solicitation, key system parameter #1 states temperature measurement is the primary interest. Is there a secondary measurement quantity of interest?

5. From the solicitation, does key system parameter #2 refer to absolute or relative accuracy of temperature measurement?
   A. 1. The Navy is interested in being able to apply these diagnostics to any Naval Aviation gas turbine engine currently operated within the fleet (from idle up to full afterburner). This does include engines as large as the F135 and F414.

2. The term particle laden is referring to particulates that would typically exist in a gas turbine engine exhaust being operated in a ground test, likely outdoor, environment. This includes soot particles naturally forming during combustion as well as any particulates that are ingested at the inlet (sand and dust), and make their way through the flow path and into the exhaust. The topic mentions these particles because, as far as the Navy is aware, most non-invasive, spatially resolved temperature measurement techniques that currently exist are significantly affected by the presence of particulate matter within the flow. There is no intent or desire to artificially seed the engine exhaust with particles to improve sensor performance.

3. Each measurement �point� must be at least 1 mm or smaller. For the final technology, the diagnostics tool would be capable to measure anywhere across the entire exhaust plume of the engine from the nozzle wall through the engine centerline at the desired recording frequency.

4. Temperature measurement is the primary interest. The other measurement parameters of interest that are discussed (pressure, velocity, combustion efficiency, and gas composition) are all of equal secondary interest

5. The described +/- 5% temperature accuracy is a relative accuracy based upon the flow temperature, not the desired instrument full range temperature. For example if the sensor was measuring in a flow with approximately a temperature of 700K, the desired accuracy of +/- 5% would be better than +/- 35K.

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