High-Bandwidth Noninvasive Sensor Systems For Measuring Enthalpy and Mass Flux in Detonation-Powered Devices

The objective of the proposed Phase-I research effort is to perform velocity, temperature, pressure, and H2O concentration measurements at the end of a detonation tube and the exhaust of a detonation-powered turbine at a rate of 50 kHz.  These measurements will help quantify the efficiencies of detonation-powered devices.  High-speed measurements of temperature, H2O mole fraction, pressure, and velocity will allow determination of the enthalpy and mass-flux in-and-out of the detonation-powered devices.  Measurements will be performed using a state-of-the-art time- division multiplexing (TDM) sensor system available to Spectral Energies through GFE.  Based on the Phase-I results and consultation with the AFRL scientists, we propose to design, build, and deliver a compact sensor system along with high-fidelity fiber-collimators for measuring velocity, temperature, pressure, and H2O concentrations along multiple lines-of-sight during the Phase-II research effort.  Despite using absorption spectroscopy for determining the temperature, pressure, and H2O concentration, the TDM technology is fundamentally different from typical diode laser-based absorption sensors and has many advantages, specifically, allowing the acquisition of many spectral lines covering wide spectral range at very high speeds (>10 kHz) and thereby providing high-speed thermometry with better temperature accuracy and power spectral density (PSD) functions.  The proposed TDM sensor system offers flexible coverage of such a broad spectral range that it is automatically suitable for virtually all applications within 5 psia and 1000 psia for a temperature range of 270K to 2700K. BENEFIT: Development of compact sensor systems for measuring temperature, pressure, and velocity at a rate of 50 kHz will enable engine manufacturers to investigate the performance of PDEs and detonation-powered devices and will also provide valuable high-bandwidth data to the numerical modeler.  This sensor system will also help studying the ignition and flame growth phenomena and monitor the combustion processes and relevant dynamical phenomena at realistic operating conditions for the first time.  This capability is particularly critical for the design and modeling of advanced, detonation-powered or ultra-compact, low-emission, gas turbine engines and for development of real-time combustion-control strategies.  This technology will yield significant payoffs in military and commercial aviation as well as land- and sea-based power generation.  This sensor system will also have broad impacts for on board sensing and control along with microscopy, biological imaging, imaging of hazardous gases, as well as other applications that require high-speed such as detonation, shock wave, and pulsed magnetic fields research.  With minor modifications, the sensor system might become important for high-speed swept-source optical coherence tomography, thus opening the door to new imaging capabilities.