Hot­wire Anemometer 1. Purpose of the experiment. Understand the working principles and used methods of hot­wire anemometer. 2. The working principle of hot­wire anemometer Fluid flows through the heater, heating fluid in the upstream side of the downstream side with a different temperature, while heating by the body cooling, these changes are related with the flow (Strictly speaking, with the fluid flow directly related to), can detect these changes in velocity and flow to achieve, a representative of the heat flow meter is the hot­wire anemometer. Place the diameter 0.025~0.15mm of platinum or nickel chromium wire as a heat source into the heating fluid. When the fluid density, specific heat, thermal conductivity is at certain, the relationship between velocity of flow and hot­wire Anemometer heat dissipating capacity Q is Q = a ´ v 1 / 2 + B (1) Where: A, B is a constant, v for the velocity of flow When the heat resistance R of and current I, so Q = I 2 R = A ´ v 1 / 2 + B (2) The velocity of flow can be measured by measuring changes in current or resistance. So is called the constant resistance law and constant current of hot­wire anemometer. 3. Experimental instrumentation Hot­wire anemometer and wind duct. 4. Experimental steps The hot­wire anemometer is placed in the duct. Observe hot­wire anemometer direction of the wind instrument when the fan is in operation.