Engine exhaust flow measurement with pulsation compensation

An engine exhaust flow meter, comprising:

• a flow tube and a differential pressure meter that is adapted to measure differential pressure in exhaust flow through the flow tube;
• a computer adapted to sample said differential pressure meter at a rate that is greater than the pulsation of the exhaust flow to obtain a differential pressure signal;
• a pulsation dampener that is adapted to mechanically reduce a magnitude of flow pulsation in said flow tube;
• and
• said differential pressure meter comprises a pitot tube disposed in said flow tube and a differential pressure sensor configured to sense pressure across said pitot tube, producing a differential pressure signal that is responsive to forward and reverse flow in the flow tube;
• said computer responsive to said differential pressure signal to compute a mean differential pressure value;
• said computer responsive to said differential pressure signal to compute a mean magnitude of pressure pulses;
• said computer is adapted to determine a compensation factor as a function of the mean magnitude of pressure pulses and adjusts said mean differential pressure value as a function of the compensation factor to obtain an engine exhaust flow value that is flow pulsation compensated.

A method of measuring engine exhaust flow rate, said method comprising:

• connecting the engine exhaust to a flow tube having a differential pressure meter that is adapted to measure differential pressure in exhaust flow through the flow tube:
• sampling said differential pressure meter at a rate that is greater than the pulsation of exhaust flow to obtain a differential pressure signal;
• computing a mean differential pressure value from said differential pressure signal;
• computing a mean magnitude of pressure pulses from said differential pressure signal;
• determining a compensation factor as a function of the mean magnitude of pressure pulses and adjusting said mean differential pressure value as a function of the compensation factor to obtain an engine exhaust flow value that is flow pulsation compensated.