velocity

Nowadays, the ceiling slot diffuser is very popular in offices. However one of the problems, for the producer and designer of linear diffusers, is to determine and specify correctly the throw-length data, in order to achieve optimal air movement in the occupied zone. Here, experimental studies were conducted to identify the variation characteristics in jet behaviour for ceiling slot diffusers. Nine cases, covering different aspect ratios, were measured under isothermal conditions in two test rooms using traversing measurement systems.

In that study, induced ventilation is experimentally explored in a small well-insulated manufactured home, located in the northern edge of the Negev desert in Israel. Temperature monitoring was performed inside and outside the building in summer along with velocity measurements inside the building. The results show that with induced ventilation the air temperature inside the home is like the ambient temperature, whereas, when no openings, the temperature inside the manufactured home is higher than the ambient.

Velocity measurements were performed in the air flow resulting from two horizontal opposite air jets along a ceiling. Results show how the air velocity decreases along each of the two air jets, compared to the velocity decrease along a single free air jet.Experimental results are compared with a correlation from the literature. The agreement is good.

This paper defines a new parameter : the equivalent frequency used for the description of the frequency characteristics of air velocity in turbulent flows.Analyses were performed to identify how much the accuracy of determination of the equivalent frequency depends on the characteristics of the velocity. Results of the analyses identified that the equivalent frequency of the velocity fluctuations in rooms is between 0.1 et 1 Hz, and 90 % of those records were between 0.2 and 0.6 Hz which is the frequency range identified to have most significant impact on people's draught sensation.