Space Air Diffusion Laboratory

Space air diffusion systems are an integral part of many HVAC systems 1-2 . The design of the system includes finding the best location for introduction of air into the room. This paper expounds on the designing, building, and testing of a space air diffusion laboratory setup for undergraduate engineering students. The laboratory will enable students to conduct hands-on experiments that involve visualization and measurements of laminar, transitional, and turbulent ceiling wall air-jets and the resulting room air motion. Students designed the space air diffusion experimental test setup for use in the Fluid Mechanics course’s laboratory and for the ASHRAE Senior Undergraduate Project Grant program, which funded the project. Three groups of students in the Manufacturing Processes course designed the experimental setup – one group designed the mechanism to position the Pitot-tube and hot-wire anemometry measurement devices in the flow field, another group designed the layout of the channel the air would pass through to become steady flow, and the remaining group designed the section which would streamline the air supplied by the fan. The overall objective was to engage the students in a design project. This paper will provide details of the evaluations and outcomes of the project. For this project, the students designed the apparatus using SolidWorks® CAD software, and ANSYS Fluent software was used for CFD simulations of the flow field. The components used in the design were: a blower, a settling chamber, a perforated plate, honeycomb, mesh screens, and a 3D printed contraction in the shape of a fifth order polynomial to minimize the turbulence level of the flow entering the 2,440 mm long plane channel made with a cross section of 10 mm high and 232 mm wide. The purpose of the channel was to get a fully developed flow entering the model room for calibration of the hot-wire anemometer. The dimensions of the model room designed by the students are 232 mm in height, 232 mm in width, and 464 mm in length. The ceiling wall jet was discharged parallel and adjacent to the straight horizontal ceiling of the model room. The jet developed along the ceiling surface of the room and entrained air from the room as its velocity deceased when it moved into the room. The maximum velocity remained close to the ceiling surface with the distance that the ceiling jet adhered to the surface depending on the relative influence of inertia and gravity.