Numerical Validation Using Finite Element To Assess The Performance Of Microwave Sensor In Detecting Blade Tip Displacement

Gas turbine engine manufacturers are in continuous strive to improve the durability and the technology behind engine development to help monitor engine health and performance. Such technologies are confined to employing highly specialized sensors within the engine compartment. The role of the sensors is to screen and track the structural response of the engine components and in particular the rotor disk due to its venerability to endure failure since it is subject to complex and harsh loading conditions. Detecting unexpected or excessive blade vibration before failure is critical to ensure safety and to achieve projected component life. Nondestructive Evaluation has been the traditional method of detection in addition to relying exclusively on visual inspections as well as other means. These methods require time and cost and do not provide accurate feedback on the health when the engine is in operation. At NASA Glenn Research Center, efforts are undergoing to develop, and test validates microwave-based blade tip timing sensors in support of these concerns and to investigate their application for propulsion health monitoring under the Transformational Tools and Technologies Project (TTTP).A set of prototype sensors is used to assess their ability and applicability in making blade tip clearance measurements in an attempt to extract the blade tip timing from the acquired raw data. The sensors are non-contact type and microwave-based technology. The study covers an experimental task to define the optimum set-up of these sensors, determine their sensitivity in making blade tip deflection measurements and validate their performance against realistic geometries in a spin rig. It also includes finite element analysis base calculations to compare with the experimental data. Data pertaining to the findings obtained from the testing as well as the analytical results are presented and discussed. This work is an extension of a prior combined experimental and computational study that is available in reference [1].