Calibration of a Long-Wavelength Acoustic Flowmeter Using a Lumped Impedance Acoustic Model
Lee J. Gorny, Keith A. Gillis, Michael R. Moldover
As a part of NISTs program to standardize measurements of greenhouse gas emissions, we are developing long-wavelength acoustic flowmeter (LWAF) for accurate, economical measurement of flue gas flows, for example, from coal-burning power plants. A LWAF is advantageous because it averages spatial non-uniformities in a flows axial flow profile over the entire cross-section of the flue. We constructed a 1:100 scale, calibrated flow facility to evaluate long wavelength techniques. Using a prototype LWAF, we obtained an uncertainty of 1 % for flows ranging from 2 m/s to 5 m/s. We present the operating principles of the prototype, our design considerations, numerical theory for the prototype, its calibration, and measurement results taken in several distorted flows. In this discussion, we identify problems that must be solved to scale up the prototype LWAF and deploy it in a power-plants stack.