Study On Mixing Characteristics Of Elliptical Jet And Its Application

Recent few decades, duckbill-shaped elastomer check valves(DBV) have been widely installed on various effluent diffusion systems. Because the nonlinear relationship exists between the volume flux and the opening of the valve, the dilution prediction of this type diffusion system is becoming a new topic in engineering application, corresponding problems as dilution prediction, evaluation of dilution effect, elliptic jet simulating DBV jet, mixing characteristics of elliptic jet itself, and how to include the prediction methods of elliptic jet or DBV jet into relatively mature models of round jet, etc. In this paper, considering the problems described above, the elliptic jet was elected as the study object. This study will not only have practical engineering application values, but also expand the knowledge of jets for us, especially the coherent structure in the non-circular jet, and enrich the contents of the theory of jet.In this paper, we firstly using the Laser Induced Fluorescence (LIF) technology systematically studied the mixing characteristics of elliptic jet with medium and high aspect ratios as well as different velocity ratios, in which characteristics compare between the two types jets were conducted all the way. At first, we used LIF technology to validate the experimental systems by measuring coflowing round jet. Then, we visualized and quantified the concentration field of coflowing elliptic jet. Furthermore, we studied the elliptic jet characteristics about the centerline dilution, jet spreading, mean concentration profile and turbulence statistics profile at different downstream stations. Analyzing the experimental data with turbulence theory, we firstly presented the prediction methods about the coflowing elliptic jet and the practical procedure that how to include prediction methods of elliptic jet into round jet models.We firstly founded the numerical model of coflowing elliptic jet based on FLUENT commercial code. After comparing features of various turbulence models and evaluating the computation resource we possess, realizable k-ε turbulence model was adopted. The numerical simulation results were proved by the physical experiments. Furthermore, we got the integral velocity field and vorticity field as well as their corresponding characteristics. Through the quantitative analysis about the vorticity field, we firstly stated the flow mechanism of the axis switching, the typical three dimensional flow phenomena exists in the elliptic jet.Using the LDV (Laser Doppler Anemometer) technology, we studied the characteristics of coflowing DBV jet velocity field with different velocity ratio. We also validated the rationality of elliptic jet simulating the DBV jet, and firstly stated the way by which the results of elliptic jet study can be used to DBV jet prediction. At the end of this paper, conclusions and future work are presented.