A High Speed Data Acquisition System for the Analysis of Velocity, Density, and Total Temperature Fluctuations at Transonic Speeds

This study focuses on the use of a high speed data acquisition system, coupled with hot wire anemometry techniques which incorporate a three wire probe, for the simultaneous measurement of velocity, density, and total temperature fluctuations. Integrating the acquisition and reduction processes into a single system provides test results in less time than a system with separate data acquisition and data reduction processes.

These processes have been substantially streamlined with the high speed Dynamic Data Acquisition System (DDAS). The DDAS replaces the FM tape recording and the post-test digitization from tape with real-time simultaneous digitization and digital recording. The manual entry of various parameters during the data reduction phase has been replaced with automatic acquisition of data (either from a computer link to an existing wind tunnel acquisition system, or from data acquisition facilities within the DDAS). The acquisition of hot wire calibration data is automated in the DDAS. The presentation of the raw and processed data, in terms of root mean square values of velocity, density and total temperature is accomplished on demand in near-real-time with the DDAS.

A comprehensive description of the DDAS and an analysis of its initial performance is presented.