INTEGRATED FLOW FRICTION SENSOR

A new application of integrated flow sensors is presented, namely the measurement of wall shear stress (the friction force that a flow exerts on the surface of an object). A thermal flow sensor chip is bonded on a ceramic carrier substrate that has its back side exposed to the flow and is mounted in the surface on which the wall shear stress is to be measured. As the sensor chip has no direct contact with the flow, simple wire bonding can be used. The relation between the flow rate and the total heat loss is measured, as well as the temperature difference on the chip in the direction of the flow. A novel feature with respect to earlier designs is the use of integrated thermipiles for the measurement of the on-chip temperature difference. Measurements are reported for turbulent boundary-layer flow.