Development of a "Digital Bridge" Thermal Anemometer for Turbulence Measurements

Thermal anemometry (a.k.a. hot-wire anemometry) has been a key experimental technique in fluid mechanics for many decades. Due to the small physical size and high frequency response of the sensors (resulting in excellent spatial and temporal resolution), the technique has been widely used for studies of turbulent flows. Even with the advent of nonintrusive techniques such as Laser Doppler Velocimetry (LDV) and Particle Image Velocimetry (PIV), hot wire anemometry is uniquely capable of extremely high frequency response and fine spatial resolution measurements. ViGYAN proposes a fundamental change to the anemometer configuration, with two related aspects. First, the circuitry to power the sensor and establish its operating point is packaged immediately adjacent to the sensor, i.e. in the typical probe holder, removing the effect of the cable connecting the sensor to an external anemometer. Second, modern analog-digital conversion hardware will be employed to the maximum extent possible, potentially including directly driving the sensor. Data transmission will then be fully digital, immune to environmental variations or electrical noise. Further, direct excitation would permit the choice of operating modes (not just variation of operating point) by changes in software. The ultimate objective of the research is therefore referred to as a "Digital Bridge".