Low-Temperature Plasma Pressure Sensor for Dynamic Ultra-High Temperature Environments

The current state of the art in pressure sensing for dynamic flow measurement is limited and in many cases not available when it comes to harsh, high temperature environments.Accurate pressure measurements of highly transient flows, e.g.combustor instabilities and other dynamic events, requires the sensing element to have the shortest fluidic path connection with the environment and therefore be located in the wall in direct contact with the hot fluid.Active cooling is used to address the high temperature to an extent, with a certain class of sensors capable of operating at temperature of up to 2000 F in this fashion.Beyond this temperature threshold, no practical solution exists for monitoring and/or measuring fluid flow pressure oscillations without a compromise on frequency response.With an increasing number of applications in the power, energy generation and advanced propulsion market segments pushing the temperature envelope by leveraging advanced manufacturing and high temperature materials, a growing need exists that can only be addressed by an ultra-high temperature capable pressure sensor with high frequency response.The proposed effort will leverage low temperature plasma as a transduction method towards the measurement of pressure dynamics in high temperature applications.The sensor solution being proposed will feature ultra-high temperature capability without compromise in frequency response (> MHz) in a small package that can be implemented in various applications, from tracking instabilities in combustion systems for power generation to health monitoring of military/commercial advanced propulsion systems.The implementation of low temperature plasma as a pressure transduction mechanism for highly dynamic, high temperature flows was investigated during the Phase I SBIR period of performance.The effort involved the development and testing of several probes with various configurations and under various conditions, ranging from static to highly dynamic environments.Static testing involved operation at sub-ambient and above ambient pressure conditions resulting in a calibration strategy, while dynamic testing involved short duration pulsed and highly transient hot flow conditions that demonstrated the unique benefits of the proposed approach.Performance data in support of preliminary design efforts for a prototype system were generated, and along with an assessment of manufacturability, lay the foundation for a future Phase II effort to mature the plasma-based sensor system as a viable measurement solution for the harsh environment test and evaluation community.The Phase II SBIR project will involve maturation of the sensing technology through rigorous design/analysis, fabrication and testing of probe configurations and associated electrical subsystems to yield a prototype integrated system that can be tested in relevant environment achieving a readiness level of TRL 6.Emphasis will be put on probe manufacturing to yield a robust and reliable build/assembly process, to include connector and packaging solutions.Integrated system testing at relevant environment conditions will be performed targeting applications of interest by identified end-users of the sensor technology.The proposed sensor system will enable high frequency pressure measurement in ultra-high temperature environments (>2500F) currently not possible by commercially available sensors.Commercial applications span from tracking instabilities in combustions systems for power generation, to health monitoring of next generation propulsion systems, to monitoring high temperature advanced manufacturing processes.