The Experimental And Numerical Study On The Characteristics Of Jet In The Flowing Ambient Fluid

The key problem for renovating water environment is the control on the origin of pollution. One of the factors polluting water environment is just the out-of-order letting of cities' polluted water. Because the cost of the waste water treated project is correspondingly cheap by letting the polluted water into rivers or sea, it has been the preferentially measure for dealing with polluted water of cities. Scientifically designing the mode of waste water letting and choosing the region of waste water letting all depend on the profoundly understanding for the polluted water's hydrodynamic characteristics and the contamination's diffusion, transport characteristics. Polluted water usually flows into rivers and sea by the mode of jet. Systemically making the basic study of the jet's characteristics in the flowing ambient fluid not only proves the understanding on the turbulent flow, but also supplies more perfect academic base for the jet's application in the production, so it has important scientific value and factual significance.This paper makes more systemically study on the jet's characteristics in the flowing ambient fluid by the experiment and numerical simulation, including the jet's flow state, expansion rate, and the distribution of concentration. In the experiment the time-averaged and turbulent characteristics of the vertical round jet in wave environment is studied by the wave flume and the system of particle image velocimetry (PIV); in the numerical simulation based on Reynolds time-averaged equations the turbulent jet's 2D and 3D numerical modes are established by the stress-algebraic turbulent model and VOF method. Numerically simulate the plan jet and round jet in the flowing ambient environment, analyze the jet angle influence on the jet's characteristics, and makes the systemically study on the plan and round jet's characteristics in wave environment.Based the experimental results of the jet's velocity field this paper summarizes the rules of the wave period influence on the length of potential core, the distribution of vertical velocity on the cross-profiles, and the jet's expansion rate. By analyzing the jet's turbulent characteristics the process of the turbulent jet in wave environment is divided into three phases. Summarize the rules of the distribution of turbulent terms on the cross-profiles and the change of turbulent terms with the wave height, and indicate that the value of the jet's turbulent diffusion is about the 1/8-1/3 of the value of convection in wave environment, so the function of the diffusion can't be ignored. Based the numerical simulated results of the jet in the cross flow this paper summarizes the rules of the jet angle influence on the position of the vortex center, separation point and dilution. The concept of "area turbulent kinetic energy" is proposed and by using this concept the relationship between mixing intensity and jet angles is analyzed. The results show that 90 degree jet angle is the most favorite condition for jet water mixing with environment water.Based the numerical simulated results of the plan jet in wave environment this paper describes the characteristics of the instantaneous velocity and concentration field, and indicates that the progress of the contamination's spreading is divided into three phases. By analyzing the period-averaged velocity field of the plan jet in wave environment this paper divides the progress of the vertical period-averaged velocity falling on the axis of the spout into four phases, and summarizes the rules of the wave height and wave period influence on the length of potential core, the distribution of vertical velocity on the cross-profiles, and the plan jet's expansion rate. The factors of the wave influence on the characteristics of the jet include: the first one is the horizontal maximum velocity of wave particle; the second one is the oscillatory wave motion. Based on the two reasons it can be conclude that the horizontal radius of wave particle motion is the essential factor affecting the characteristics of vertical jet, and the horizontal radius of wave particle motion is larger, the effect on the characteristics of vertical jet is more remarkable.Based the numerical simulated results of the round jet in wave environment this paper describes the 3D characteristics of the instantaneous velocity and concentration field, and emphasizes the contrast between the instantaneous velocities, concentration fields in the two vertical plans through the axis of the spout. In addition the conclusion is obtained that the pairs of kidney vortex has the highest frequency in all the vortexes in the horizontal plan by analyzing the vortex and velocity fields in the different cases. Summarize the rules of the wave terms influence on the rate of the 3D jet expansion by analyzing the period-averaged velocity field of the round jet in wave environment, and emphasizes the contrast between the rules of the wave terms influence on the rate of the 3D round jet expansion and the 2D plan jet expansion.