| In the present dissertation, the flow and it's characteristics in an adjustable jet pump are investigated theoretically and numerically. The method for designing this kind of jet pump is also discussed. Firstly, the characteristic equation and the optimal section ratio equation of the adjustable ejector are derived on the basis of mass conservation and momentum conservation. The differences of the above-mentioned equations between the adjustable jet pump and the fixed ones. Then, the influences of some main fluid parameters on the characteristics of the interior flow are analyzed. It shows that the inject ratio can be increased significantly by increasing the pressure of the main fluid, the secondary fluid and the mixing fluid, and a similar result is also obtained by means of reducing the pressure ratio. The area ratio at the section of the nozzle outlet (ξ) is another important infector. The results show that the inject ratio curve became steeper when the value of ξis bigger, and then lead to the adjustable range of the operating parameters involved pressure are narrowed, which is bad for the adjusting performance of ejector. In this thesis, ξ<0.22 is suggested. A simple physical model and interior flow mathematic model has been developed according the characteristic of the structure and flow of the adjustable ejector. The interior flow of the ejector is simulated by means of PHOENICS, and the conclusions about velocity flow field, pressure distribution and inject ratio depends on the influence of some parameters are drawn. The effect of the structure of the probe on the performance of adjusting flow rate is discussed, an equator of quadratic surface of the probe is developed, As a result, the flow rate of the injector can be regulated linearly.
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