Development Of High Precision Flow Field Measurement System Based On RS485 And TCP/IP Protocol

Porous probe is a kind of pneumatic measuring device which can obtain the flow velocity,direction,total pressure and static pressure.It is the most widely used tool for engine flow field testing.Research and development of a fast and accurate porous probe Aerodynamic testing system can improve the testing efficiency,and more accurately verify the performance of compressor and turbine blade,and then modify the design.In this paper,three kinds of test systems suitable for different flow field conditions are developed and designed,by learning the process of flow field measurement with porous probe and interpolation calculation method,and combining with the techniques of signal acquisition and proeessing,signal transmission and anti-interference.They are:1)test system based on RS485 bus,each sensor is used as a separate communication between the lower computer and the upper computer,so this test system does not need to use analog data acquisition card,high precision,low cost,easy maintenance,suitable for low cost,less channel data acquisition system;2)the test system based on TCP/IP protocol is equipped with a 32/128 channel analog quantity(4-20ma)acquisition card designed and developed independently,which makes up for the shortage of other acquisition cartoon channels in the market(mainly 8-channel acquisition)and the poor anti-interference ability of acquisition voltage.It is suitable for the use of multi-channel data acquisition system.3)the mixed test system based on RS485 and TCP/IP transmission protocol is equipped with multiple 8-channel analog quantity(4-20ma)acquisition cards,and each 8 sensors are listed as one acquisition unit.At the same time,the self-developed TCP/IP conmunication protocol motion controller is installed to realize the function of integrating signal acquisition and control probe displacement.This kind of test system has good expansibility,rich function integration,high collection accuracy,fast data refresh frequency,and is suitable for high-end customers.At present,three kinds of testing systems are useing in many universities and research institutions,such as Shanghai Jiaotong University,Xi’an Jiaotong University,Harbin Engineering University,Hitachi Ari-Conditioning and so on.