Research On Accurate Extraction Method Of Aero-Engine Blade Tip Clearance Under Under-Sampling Condition Based On Compressed Sensing

Aero-engine is the main power device of aircraft,and the accurate measurement of its running parameters provides important reference for engine condition monitoring.As an important operation monitoring data,the blade tip clearance characterizes the distance between the engine turbine blades and the casing.If the blade tip clearance value is too large,it will reduce the efficiency of the turbine and increase the fuel consumption of the engine.If it is too small,it may cause the blades to collide with the casing,causing wear of the casing or blades,threatening the safety of engine operation and causing huge safety hazards.Therefore,the accurate measurement of the tip clearance value is an important means to realize the closed-loop control of the engine.Traditional tip clearance measurement studies mainly focused on new measurement principles and methods,however with the increasing of engine speed,the traditional methods cannot meet Nyquist sampling theorem in sampling frequency,thus the accurate extraction of tip clearance values will be affected.To solve this problem,this thesis focused on an accurate extraction method of blade tip clearance with under-sampling condition based on compressed sensing.The main research contents are as follows:1.Firstly,in order to study the variation range of aero-engine tip clearance and provide data support for the tip clearance measurement method,this thesis used Ansys Workbench fluid-solid-thermal coupling model to carry out simulation analysis,and simulated the variation of tip clearance under different temperatures,rotational speeds,and flow rates law.The main influencing factors of the blade tip clearance were explored,and the deformation range of the blade was obtained.The blade deformation range provided a numerical reference for the accurate extraction of the subsequent blade tip clearance;2.Secondly,in view of the problem that the undersampled tip clearance measurement data could not be accurately reconstructed using the Nyquist sampling theorem,this thesis studied the undersampled data recovery method based on compressed sensing.Based on the characteristics of tip clearance sampling data,the construction methods of sampling matrix and sparse matrix were mainly studied.This thesis also designed an effective data reconstruction algorithm to achieve accurate extraction of tip clearance;3.Finally,this thesis used the laser triangulation method to verify the above algorithm,built a simulated blade rotor platform,and obtained the blade tip clearance measurement data through different sampling frequencies.The data with high sampling frequency was used as the true value,and then the under-sampling data was processed to realize the accurate reconstruction of the tip clearance data under the under-sampling condition,the effectiveness of this method was verified.