Air distribution measurement in a room with a sidewall jet: A 3D benchmark test for CFD validation

In mixing ventilation systems, diffusers are often located on side walls and supply quasi-free air jets above the occupied zone. The aim of the current research was to create a new CFD 3D benchmark with two well-defined characteristic zones in the room, i.e., the quasi-free jet zone and the occupied zone. The measurements were performed in a physical scale model (1:5) of the room. The kinematic similarity criterion was fulfilled by the equality of the Reynolds numbers in the model and in the prototype. Measurement methods adequate for air velocity and speed measurement were applied: laser Doppler anemometry for the axial velocity component in the jet and low velocity thermal anemometry for the air speed in the occupied zone. The novelty of the paper is the identification of the evolution of the air mean velocity distribution with distance from the supply opening. In the distance of 15-30 equivalent diameters, the jet behaves as a free turbulent axisymmetric jet; its momentum flux is conserved and fixed at approximately 80% of the inlet momentum flux. At higher distances from the inlet, the confinement effect of partitions is observed. The CFD results validation and reporting methods applicable for the benchmark data are proposed. The new 3D benchmark can be useful for CFD researchers, engineers and students for testing different CFD modelling aspects and thus may contribute to the improvement of CFD prediction accuracy. The benchmark results are available in the Data in Brief article.