NA-04-6-2 – Characterization of Airflows at the Exit of Registers Using Laser Doppler Velocimetry (LDV) PDF

This paper reports the results of fluid flow measurements carried out at the exit of sidewall registers. Time-averaged mean velocity and turbulence (local root mean square velocity fluctuation) profiles were measured at the exit plane of two commonly used 8 in. X 4 in. (203 mm X 102 mm) sidewall registers. These data can then be used as an input boundary condition in a computational fluid dynamics (CFD) code to predict the velocity and temperature distribution in an enclosure supplied by the registers.

Laser Doppler velocimetry (LDV) was used to measure the axial and vertical components of the velocity vector at various locations across the face of the registers. Measurements at distances removed from the exit plane of the registers, but still within the “near field,” show how the complex profile due to the vanes transitions to a jet, and this can provide a partial validation measurement for the CFD results. Measurements were made at two different flow rates, and the evaluation of the results suggests that the velocity field at the exit of both of these registers scales with the flow rate through them. This means that, in the mode of operation in which the supply fan (of an HVAC system) has a “high” and “low” setting, similar velocity scaling would result for these types of registers.

Units: SI