Inventors:
Dennis A. Stanke - La Crescent MN
Paul C. Rentmeester - La Crosse WI
Paul D. Ulland - La Crescent MN
Assignee:
The Trane Company - La Crosse WI
International Classification:
G01F 168
Abstract:
Apparatus are disclosed for sensing the velocity of a fluid stream, as may be flowing in a duct, pipe, or the like, which fluid stream exhibits variations in its temperature under different operating conditions. The apparatus includes a first probe which is exposed to the fluid stream and includes first temperature sensing means for sensing the temperature of the fluid stream. A second probe is provided which is disposed within the fluid stream and includes at least a portion constructed of a thermally conductive material. Heater means are disposed in thermally conductive relationship with said thermally conductive portion, and second temperature indicative of the temperature of said heater means. Third temperature sensing means are provided for sensing the temperature of the thermally conductive portion of the second probe at a point removed from the heater means, which temperature is a function of the heater means temperature, the fluid temperature, and the velocity of the fluid flowing thereover. In order to compensate for variations in the fluid temperature, heater control circuit means are provided for receiving temperature signals from the first and second temperature sensing means and for controlling the heat output of the heater means so as to maintain substantially constant the temperature difference between the fluid and heater means.