Probe for particle position and velocity vector measurement. Technical note.

摘要

The Morgantown Energy Technology Center (METC) has been developing an instrumentation system to monitor the dynamic behavior of particles in fluidized beds with minimum disturbance of particle motion. During the first phase of development, a particle velocity probe and a supporting electronic system have been designed and tested. This probe provides a tool for measuring particle velocity at various points within a cold fluidized bed operating in different regimes. When used in complementary fashion with particle impact probes, density imaging systems, and other measurement systems, the velocity probe will contribute to the generation of a data base for supporting the advancement of fluidized-bed technology. It features a miniature, six-electrode, capacitance-based sensing head that is excited by a sinusoidal voltage having a peak-to-peak voltage of up to 500 volts and a frequency of 2 megahertz (MHz). The sixth electrode, placed between the sensing and ground electrodes, extends the particle-sensing volume farther above the probe head. Capacitive currents flowing between four sensing electrodes and ground are influenced by the presence and position of a particle passing by the probe head. These currents are amplified and synchronously detected to produce positional x, y, and z values that are then converted to digital form. The resulting digital values of x, y, and z at two values of time are used with an internal time base to generate values of the three components of the particle vector. METC researchers expect to make a more miniature probe and to increase its sensitivity and accuracy. 7 refs., 9 figs.