High Bandwidth Plasma Sensor Instrumentation for the Measurements of Turbine Inlet Conditions

ABSTRACT: Modern gas turbines must reduce emissions while demonstrating improved efficiency, durability, and performance. Designers are using higher compression ratios and peak temperatures to meet these goals. Flows in the area of the turbine inlet are highly unsteady, non-uniform, and 3-dimensional. The lack of information of inlet conditions in the turbine results in faulty distribution of cooling flows in the stage 1 nozzle leading to durability issues. These challenges make it difficult for turbine designers who need accurate estimates of inlet boundary conditions. Current measurement techniques can not provide the necessary time-resolved information. In Phase I, we demonstrated the feasibility of a new class of AC plasma sensor for high enthalpy flows. These sensors feature very high bandwidth (1MHz) and spatial resolution (1 mil) in a low-cost, simple, and rugged design. Using these designs, multiple sensors can be mounted on rakes to provide turbine inlet flow conditions over planar regions. During Phase I, measurements of pressure fluctuations in the exhaust of a gas-turbine were performed at 1600F and operation up to 3500F is possible with current materials. In Phase II, we will extend the operating capability of these sensors to 4500F using film-cooling techniques. The sensors developed under Phase II will be demonstrated in realistic engine environments and appropriate measurements such as temperature, pressure, and mass flow will be made. Significant efforts will also be made for tech transition and commercialization of the proposed sensors. BENEFIT: Research performed during the Phase II study will provide a suite of rugged sensors that are optimized to measure multiple parameters, such as temperature, pressure, and mass flow. These sensors will have all of the native advantages provided by the plasma approach including extremely high frequency response greater than a MHz, high sensitivity, excellent noise rejection, robust architecture to withstand high loads and temperatures, and a micro-miniature scale through MEMS packaging.