Data Acquisition and Control System for On-line Measurement and Analysis of Complex Flow Fields

The accurate measurements in complicated flow fields like the reversal and wake flows are representing a challenge for the fluid dynamics researchers. The present paper deals with the description of a developed flying X-hot-wire probe / computer interfacing technique which enables detailed turbulence evaluation within reversal and wake flows. The probe attacks the flow and sweeps within the flow field with a velocity higher than the reversal flow velocity. The signals at 19 pre-selected points (per sweep) in the flow field are transferred to a minicomputer for on-line data acquisition and analysis. The main components of the system are the flying hot wire mechanism, motor control unit, interfacing unit and a minicomputer. The electronic components and their programming and functioning are described in details in this paper. The validity tests of the developed system are presented and discussed. The results showed that the system is capable to measure the 2-D velocity components in mean velocity of around 5 m/s within an error limit of ± 0.9%. For higher mean velocity, of 19.7 m/s, the system measures the two velocity components with an error limit of ± 0.57%. Within such limits of errors, the system is verified for measurement in complex flows with good accuracy.

Keywords: Flying Hot Wire; Interface; Complex flow measurement; Hot-wire Anemometry; Signal analysis.