Characteristics Of Jet In Flowing Ambient

ABSTRACTIn this paper, the characteristics of velocity fields and concentration fields of jets at different velocity ratios in counterflow and coflow ambient are studied in detail. The preliminary results of velocity fields of jet in reciprocating ambient are also acquired.The main conclusions include as follows:1. The advances in the research of the characteristics of buoyant jets, the measurement techniques in experimental investigations and the behavior of buoyant jets in different flowing ambient are reviewed. Also, the necessary and feasibility of the applications of precise instruments in the investigations of jets in counterflow, coflow and reciprocating ambient are pointed out.2. Including the Acoustic Doppler Velocimeter (ADV) and Planar Laser Induced Fluorescence (PLIF) measurement techniques, the whole experiments and its analysis systems are established for measuring the characteristics of velocity fields and concentration fields of turbulent round jets in different flowing ambient.3. Using ADV instruments, the experimental investigations into the behavior of a round jet in stagnant ambient are conducted here. The mean and turbulence characteristics of velocity fields are acquired and analyzed through comparing with the existing results.4. The mean and turbulence characteristics of velocity fields of turbulent round jets at different velocity ratios in counterflow and coflow ambient are investigated thoroughly. The influences of velocity ratios on the jet characteristic parameters are also studied.5. PLIF techniques are successfully developed to visualize and quantify the mean and turbulence characteristics of concentration fields of turbulent round jets in counterflow and coflow ambient. The cross-sectional scalar concentration fields, the characteristic jet width and the centerline dilution along the jet axis are also acquired.6. Based on the conservation of momentum flux, the two different theoretical equations, which can be used for the predictions of the characteristic width of jets in counterflow and coflow ambient individually, are derived.7. Based on the conservation of mass flux, the theoretical equation of the centerlinedilution along the axis of jets in coflow ambient is developed.8. Further, the characteristics of velocity fields of a turbulent round jet in reciprocating ambient are investigated preliminarily, and the other influence factors on the dilution and mixing of the discharging pollutants at the outfall are discussed.