Novel C/T technique in LDA System

Abstract

Laser Doppler Anemometry (LDA) is a most advanced velocity measurement technique in the field of fluid mechanics, combustion, hydraulics, chemical engineering, meteorology, biomedicine engineering and industrial manufactory for its non-contact, high response, and real-time velocity measurement. In LDA technique, optical signal processing is very important and very complex due to complicated flowing properties of fluid. LDA system includes optical section and signal processing section. In conventional LDA system, these two sections are separated and perform their own functions individually. Because optical section has no active control to measured signal, only mechanically indicates the variation of measured signal, the signal processing section was designed complex and costly. The existed signal-processing methods have different problems which limited the application and in turn increasing the difficulty of signal processing to detect the complex fluid. This paper describes and analyzes a new technique, C/T technique which combined optical section and signal processing section together, made the output signal simpler and solved the problems occurred in tradition methods. On the basis of analysis of C/T method, system construction is described.