SE—Structures and Environment: Measurements of Isothermal Compact Ceiling Jets Generated by Rectangular Wall Inlets

Studies of the development of the compact ceiling air jets generated by rectangular wall inlets were carried out. Two types of inlets were applied in the experimental studies. One inlet was designed with an elliptic profile in the contraction section according to the ISO standard for a long-radius nozzle (ISO inlet). Another was a pre-manufactured side-wall inlet with bottom-hinged flap and a top guiding plate (flap inlet). The inlets were placed in the inlet wall and the openings were 0·49 m from the ceiling with an incline angle of 20° pointing upward to the ceiling. Results showed that the three-dimensional jets created by the two types of inlets had similar characteristics in the fully developed turbulent regions. In the vertical symmetric plane, the jet velocity profiles may be represented by a universal similarity model with consideration of the shear stress caused by the ceiling. In the horizontal plane parallel to the ceiling, jet velocity profiles may be described by a Gaussian distribution model. The estimated horizontal distances from the inlet opening to the virtual origin of zero were applied according to the analysis of centre velocity decays of the jets. The velocity decay constants were 5·8 for the ISO inlet and 3·6 for the flap inlet. The jet generated with the flap inlet had lower maximum centre velocity and wider spread angle than the jet created with the ISO inlet. Non-linear model estimation resulted in the jet expansion coefficients of 0·07 and 0·32 for the ISO inlet and 0·08 and 0·50 for the flap inlet in vertical and horizontal directions, respectively.