Entertainment co-efficient surface jet

Abstract

The thesis presents the results of an experimental study on the entrainment coefficient of a circular non-buoyant surface water jet discharging into quiescent ambient water. The thesis consists of seven chapters. Chapter I gives an introduction to the jet problem in general and entrainment phenomenon in particular. Attention is drawn in this chapter to the fact that thermally elevated wastewater effluents from power plants are usually discharged as surface jets and there is a need to know the value of entrainment coefficient of such jets. The present experimental study is considered to be a first step towards filling this information gap. A definition of entrainment coefficient is given in Chapter II. This is followed by a brief review of relevant literature. From the literature survey, it is brought out that there is no information on the value of the entrainment coefficient for the case of circular non-buoyant water jets issuing at the surface of quiescent ambient water. Chapter III gives details of the experimental arrangement of the jet issuing into the ambient water. The details of the manometer used to measure the velocity are also furnished in this chapter. The experimental data is analysed in Chapter IV to verify the similarity of velocity profiles in the lateral and vertical directions, beyond a certain longitudinal distance from the issue point of the jet. The similarity is shown to exist in both the directions. Empirical equations describing the non-dimensional velocity are proposed. The distributions which can be described by the sum of two exponential terms are found to be similar in form in both lateral and vertical directions. The ratio of the depth scale at various lateral distances to the depth scale at the jet axis is shown to be only a function of the ratio of the lateral distance to the lateral scale at the surface, in Chapter V. An empirical relationship is proposed. This empirical relationship is used in evaluating momentum of the flow at various sections and to show its conservation. Chapter VI deals with the computation for the entrainment coefficient. A constant value of 0.0145 is obtained in the range of jet velocities studied. This value is constant along the length of the jet and it is lower than the value for the case of a submerged non-buoyant jet, as one would expect. Chapter VII lists the conclusions of the study.