Uniaxial Heat Loss Anemometer in Power Save Regime

Abstract

A new uniaxial heat loss anemometer was formed using the NTC thick film segmented thermistors with reduced dimensions. The thermistors where printed of modified nickel-manganite paste and sintered at 850 °C/10 min in the conveyor furnace. The uniaxial anemometer was formed using segmented thermistor as a heater/sensor and the housing made of thermo-insulating material; the thermistor was placed in the cylindrical cavity of the housing along the main axis. After that, segmented thermistor was self-heated at constant DC voltages in power save regime. The thermistor power save regime was introduced using duty cycle ratio 30 s/300 s (thermistor self-heating/cooling period). The constant DC voltages were changed in steps related to the air temperature sub-ranges. The thermistor self-heating current I30 in 30th second of the cycle was measured as a response to wind velocity at different angles of wind blowing and at different air temperatures (calibration curves). The use of reductors enabled moderate slope of calibration curves and extended measuring range. The properties of the new anemometer were compared with the other heat loss anemometers and digital vane-type anemometers.