Air flow rate measurement with various differential pressure methods

There are various differential pressure methods to measure the air flow rate in a closed duct. These methods are defined by ISO standards, thus providing measurement with high accuracy. General practise for air flow rate measurements with gas turbine engines is to measure depression in the throat of a flare or Venturi inlet system. However, such a measurement does not comply with any standard and thus has to be calibrated in order to obtain the so called discharge or flow contraction coefficient. With a goal of evaluation of this coefficient three different methods of the air flow rate measurement for a small turbojet TJ100 are compared and discussed in the presented research.