Method and system to measure gas flow

An acoustic-vortex resonance flowmeter comprising:

• an acoustic wave generator configured to be disposed in a gas flow path, the acoustic wave generator having a body that includes a tubular flow channel with an internal surface having a plurality of alternating channels and ridges extending annularly around the internal surface in a direction substantially perpendicular to a central axis of the tubular flow channel, wherein the channels and ridges are disposed in a regular repeating pattern along the central axis to passively generate inside the tubular flow channel acoustic emissions in response to the flow of gas through the tubular flow channel, wherein the regular repeating pattern of channels and ridges extends over a length L of the tubular flow channel and has a corrugation size b, wherein the length and the corrugation size are tuned to cause the acoustic emissions to (i) resonate with the tubular flow channel and (ii) have a frequency signature that varies with the velocity of the gas;
• and
• an acoustic sensor positioned external to the gas flow path, near an outer surface of the acoustic wave generator's body, the acoustic sensor configured to generate a signal representative of the generated acoustic emissions.