Systems and methods for operation of a sonic anemometer

A method of determining at least one of sound speed or flow speed in a low pressure environment, the method comprising:

• obtaining bi-directional acoustic data from a plurality of ultrasound transducer pairs as acoustic signals interact with a fluid in between the plurality of ultrasound transducer pairs;
• measuring at least one of flight times or phase lags corresponding to the bi-directional acoustic data;
• calculating at least one of a sound speed in or a flow speed of the fluid corresponding to each ultrasound transducer pair from at least one of the bi-directional flight times or phase lags;
• accessing a system model that relates wake effects to a transfer function corresponding to the plurality of ultrasound transducer pairs;
• correcting for wake effects, using the system model by:
• i.) measuring a wake parameter associated at a plurality of flow directions and a plurality of Reynold's numbers,
• ii.) estimating a current incoming flow direction using current and previous flow measurements;
• iii.) determining a current temperature and pressure;
• iv.) determining the Reynold's number using the incoming flow direction, flow speed, and the current temperature and pressure;
• v.) calculating a corrected flow speed and direction by applying the wake parameter corresponding to the Reynold's number;
• vi.) repeating step iv.) using the corrected flow speed and direction;
• and
• vii.) repeating steps iv.)-vi.) until a converged flow speed and direction are obtained;
• and
• generating a report including at least one of a sound speed in or the flow speed of the fluid.

A sonic anemometer system for low pressure environments, the system comprising:

• a plurality of ultrasound transducer pairs, each ultrasound transducer pair comprising:
• a first ultrasound transducer configured to operate as at least one of a transmitter or a receiver of an acoustic signal;
• and
• a second ultrasound transducer configured to operate as at least another of the transmitter or the receiver of the acoustic signal;
• a controller in communication with the plurality of ultrasound transducer pairs, and configured to:
• obtain bi-directional acoustic data from the plurality of ultrasound transducer pairs as the acoustic signals interact with a fluid in between the plurality of ultrasound transducer pairs;
• measure at least one of flight times or phase lags corresponding to the bi-directional acoustic data;
• calculate at least one of a sound speed in or a flow speed of the fluid corresponding to each ultrasound transducer pair from at least one of the bi-directional flight times or phase lags;
• access a system model that relates at least one of temperature effects or pressure effects to a transfer function corresponding to the plurality of ultrasound transducer pairs;
• correct for at least one of temperature or pressure effects by:
• measuring parameters of the transfer function as a function of temperature or pressure;
• determining a current temperature or pressure corresponding to the plurality of ultrasound transducer pairs;
• determining, using the current temperature or pressure, a phase contribution of the plurality of ultrasound transducer pairs to the measured parameters of the transfer function;
• and
• subtracting the phase contribution from at least one of the measured phase lags or flight times;
• and
• generate a report including at least one of a sound speed in or the flow speed of the fluid.