| 摘要 |
<p>THERMAL ANEMOMETER A thermal anemometer arranged to measure air velocity over a wide range of ambient temperatures and velocities, and a method of measuring such air velocity free of influence of ambient temperature, in which the anemometer comprises a probe containing two separate and distinct sensing elements, and a hand held electronic read out unit that contains sensing signal electronic processing circuitry, function control, and an analog read out meter, with the probe and read out unit being interconnected by a self coiling cable. The probe sensing elements are a self heated thermistor and a solid state temperature sensing device, that are separately but simultaneously exposed, in use of the instrument, to the air flow, with the energy consumed by the thermistor, and its resulting signal, being an indication of both the velocity of the air stream and the difference in temperature between the forced operating temperature of the thermistor and the air stream ambient temperature. The solid state temperature sensing device is a temperature sensing transistor, and develops a signal that is proportional to the air stream temperature. The two signals are electronically combined at the read out unit to eliminate the effect of any ambient temperature variations, to provide an air stream velocity reading at the meter that is independent of ambient temperature.</p> |
