Experimental Investigation and Uncertainty Analysis of Constant Voltage Anemometer Using Low-Cost Sensor
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RESEARCH PAPER
Experimental Investigation and Uncertainty Analysis of Constant Voltage Anemometer Using Low-Cost Sensor V. Sivakami1 • B. Vasuki1 Received: 26 January 2019 / Accepted: 29 February 2020 Shiraz University 2020
Abstract Hot wire anemometer (HWA) is a widely used instrument to perform experimental measurements in laminar, transitional and turbulent flows. A pure, low-cost tungsten filament from an ordinary light bulb is utilized as a hot wire sensor for the analysis of different configurations of constant voltage anemometer (CVA). Experiments are carried out with the proposed sensor for all the three modes of CVA in a self-designed wind tunnel with the laminar flow; the measured velocities are in the mean range of 0.13 m/s to 0.37 m/s. The low-cost sensor is capable of maintaining a constant voltage in spite of the variation in the sensor current caused by fluctuations in the air velocity, in comparison with any commonly used hot wire sensors. Uncertainty analysis is carried out for the proposed low-cost sensor-based CVA measurement system. The maximum standard uncertainty for the output voltage of CVA is less than 0.229 mV for the whole range of measurement. The uncertainty budget is presented along with the estimating procedure. The expanded uncertainties with a 95% confidence level for the basic, compensated and composite CVA are 0.5092, 0.4028 and 0.5148, respectively. This CVA measurement system with an alternative low-cost sensor in a self-designed wind tunnel for laminar flow is a simple, inexpensive and compact model and is proved to be an equitable standby for the CVA Tao systems. Keywords Low-cost tungsten filament Hot wire sensor Hot wire anemometer CVA mode Air velocity measurement Uncertainty analysis
1 Introduction Hot wire anemometry is a powerful and reliable technique for the measurement of air velocity. The principle of hot wire anemometer (HWA) is based on heat transfer by convection method; if a sensor is placed in the flow of air, any change in the medium will cause a notable shift of heat loss in the sensor (Brunn 1995). Generally, HWA is classified into three types, namely constant current anemometer (CCA) (Bandara 2011), constant temperature anemometer (CTA) (Sanyal et al. 2006; Wicaksanaa et al. 2009) and constant voltage anemometer (CVA). & V. Sivakami [email protected] B. Vasuki [email protected] 1
Department of Instrumentation and Control Engineering, National Institute of Technology, Tiruchirappalli 620 015, India
Among the types of HWA, CVA is the most recent development in the field of HWA and hence is least researched. Mangalam et al. (1992) detail the features of CVA, which is used explicitly for airflow measurements, and its performance is compared with a conventional anemometer. CVA finds a lot of appreciation and uses in the field of high-speed as well as low-speed flow. The working principle of CVA is described in detail by Sarma (1993). An op-amp circuit that maintains a constant sensor voltage irrespective of sensor resistance variation is also pa
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