operating mode and the use of hot wire anemometer

1. Working mode

hot wire anemometer has two working modes:

1. A constant flow, which is also called current method, namely heating wire current remain unchanged, the temperature of the gas after take away part of the heat of wire is lower, the more the greater the flow velocity temperature lower; The temperature change, the hotline resistance change, both ends of the voltage changes, and measured the temperature of the wire can be learned that the size of the flow velocity.

1。 2 thermostat, which is also called resistance method ( The method of constant temperature) , changing the heating current to supplement gas take away heat, and make the wire temperature remains constant ( Also known as wire resistance constant) 150 ℃, such as keeping; When the velocity is the greater the heating current is also needed, according to the applied current ( The heating current value) Can know the size of the flow velocity. Thermostat than constant flow application more widely.

2。 Use

hot wire anemometer is the main purpose of the following:

1. Measuring the average flow velocity and direction.

2。 Measurement to flow pulsation rate and its frequency spectrum.

3。 Measure the Reynolds stress and turbulent two speed correlation and time correlation.

4。 Measure the wall shear stress ( Is usually used with wall is placed flush hot film probe, principle similar to hot line speed) 。

5。 Measure the fluid temperature ( Probe resistance is measured in advance along with the change of fluid temperature curve, and then according to the measured resistance can determine the temperature probe) In addition also developed many professional purposes.