A Pulse Radar Front-End Research For Tip Clearance Measurement

Tip clearance refers to the distance of the motor rotor blade tip from engine box.Tip clearance of real-time measurement technology in the field of civil and military engine research and monitoring is very important.Reduce the tip clearance can improve the efficiency of the engine,reducing the consumption of energy,but the too-small-gap can bring danger to the operation of the engine.On the premise of ensure the safety of the engine,needing to minimize tip clearance.the real-time measurement technology of reason in view of the tip clearance occupies the important position in the field of engine research.This article first introduces the commonly used several kinds of tip clearance measurement method,based on the analysis comparison found that the microwave technology can be applied to the blade tip clearance measurement.Then this paper analyzes the main theory of radar front-end,studied the working principle and main structure of pulse radar transceiver front-end,according to the theoretical basis and the index requirements,puts forward the overall design scheme of pulse radar transceiver front-end,completed the design of each module circuit in a transmitter and a receiver.This paper puts forward a kind of microwave pulse signal is used to measure the tip clearance,the method of using the 24 GHz frequency,binging the characteristics of the cycle is short,is used to launch two pulse signal(pulse firing twice respectively have goals and objectives).The interval of two pulse signal is N * T(T cycle for carrier,N integers),to compare two receives the echo phase information,tip clearance is obtained by signal processing.The main work includes:Firstly,the basic theory of radar was analyzed,and the overall design and the structure were proposed.Secondly,complete the phase-locked source,pulse signal source,the design of the filter and frequency doubling module,and draw the map of each circuit module.Then,depending on the needs of system,appropriate RF chips were selected.The layout of the transmitter and receiver were implemented,which determines the final circuit's layout and the whole structure.Finally,assembling,debugging and test of front-end's each module were done.In the meantime,the results of test were analyzed.