Real-time Test Method For Dynamic Oil Film Pressure Distribution Of Journal Bearing Basing On Piezoelectric Thin Film Sensor

Oil film pressure is one of the most important basic parameters of thejournal bearings and also a hotspot in rotor-bearing system research areas.Although theoretical calculations, simulation and indirect experimental testmethod are widely used, there is a big limitation on accuracy andpracticality. Nowadays, no effective direct test method has been introduced.This paper presents a new method based on the piezoelectric thin filmsensor to test dynamic oil film pressure real-time directly, and analysis thestatic and dynamic characteristics of the oil film. The paper mainlyincludes the following aspects:(1) In connection with oil film distribution of the radial circular wattjournal bearing, the sensor structure is designed and the performance of thetwo kinds of piezoelectric materials (PVDF and EMFI) is made acomparison analysis (including output linearity, sensitivity with frequencyand temperature effects, etc.). Taking journal bearing oil film pressuredistribution into account, the array and the cable way of the sensor aredesigned, and analysis their own features.(2) According to the sensor array, the real-time simultaneousmulti-channel data acquisition system is developed, including signalpreamplifier circuit, hardware and software solutions, and signal chipselect circuit. To overcome the sensor arrays arranged in a limited spaceand reduce leads and signal crosstalk, signal chip select circuit isdeveloped, at the same time, for the problems encountered in the design process like clock signal, the signal crosstalk, signal switching instability,unsynchronized and initial sample uncertainty, solutions are proposed andverified by experiments.(3) The dynamic oil film pressure test on Bently rotor is conductedunder discontinuous oiling and continuous oiling situations and analysisPVDF piezoelectric film sensor output signal, which preliminary provethat the feasibility of PVDF piezoelectric thin film sensor to test thedynamic oil film pressure directly is good.(4) Experimental formula is put forward for the test of the oil filmforce and oil film dynamic characteristics coefficient basing onpiezoelectric thin film sensor. The experiment is carried out on therotor-journal bearing experimental stage, which also tests the coefficient ofstatic and dynamic characteristics of the oil film through analyzing thesensor output signal by using EMFI piezoelectric film sensor, whichfurther proves the excellent feasibility by using EMFI piezoelectric filmsensor to measure journal bearing dynamic oil film pressure distribution.(5) Making a comparative analysis between the calculation, simulationresults with Reynolds equation, ARMD software and experimental resultson oil film pressure distribution and dynamic characteristics verify theconsistent of these three different results as a whole, and proves theexisting computing methods are basically right, but also point out theirshortcomings.