Turbulence measurements with pulsed Doppler ultrasound employing a frequency tracking method.

A phase lock loop method of tracking doppler ultrasound frequencies is applied to the measurement of turbulent velocities. A pulsed Doppler ultrasound system capable of detecting two velocity components was employed to resolve axial and radial velocity components at the centerline of turbulent pipe flows and distal to stenoses in pulsatile flow. Measurements with the ultrasound system are compared with laser Doppler and hot film anemometer data. The results demonstrate that the phase lock loop method of tracking accurately follows turbulent velocity fluctuations for turbulence intensities up to approx. 20%, after which signal dropout becomes a significant factor. An important application of the method is that of detecting flow disturbances created by mild to moderate degrees of stenosis in arterial disease.