Abstract: A method is provided for detecting flow bifurcation during sonic flow conditions to identify shock location. The method includes setting the initial test conditions, either by setting up an altitude and airspeed in a test aircraft or by setting up an initial flow condition in a wind tunnel. The method for detecting flow bifurcation during sonic flow conditions to identify shock location requires an array of hot films be attached to an aerodynamic surface where shock is expected to impinge. These hot-films are connected to a bank of Constant Voltage Anemometers (CVA), one CVA for each hot film. After reaching the altitude where the testing is to be done, (or attaining the reference condition in a wind tunnel), a pilot initiates an auto-initializing sequence before the onset of a shock, typically at a low speed condition. This sets the current in each sensor to identical values and sets the sensor temperature above ambient temperature of the reference conditions.

Abstract: A broad-range, multi-directional aircraft airspeed measuring system is provided. The airspeed measuring system has multiple vortex generating probes located within a venturi section. At least one rearward facing probe and one forward facing probe are included. Additional probes can be added to extend the high speed range of the airspeed indicator. A splitter plate or plates separate flow channels from each other to provide a separate flow channel for each vortex probe. Each vortex probe has a hot film sensor and anemometer.

Abstract: A method for compensating for the time constant (delay time) of hot-wire/hot-film in a constant voltage anemometer is provided. The method is a two-part series of steps, the first series for measuring the time constant in a particular wind tunnel setup and a second series for compensating for the measured time constant. The first series or measuring steps include setting up a hot-wire/hot film for a particular test at a specific operating point. A step increase in sensor current is applied and the resistance change of the sensor is measured. The time to reach 63% of the final resistance value is recorded. (The time constant is defined as the time to reach 63% of the resistance value). The measured time constant value is used to match the time constant in the CVA circuit.