경사진 흡입관이 부착된 분사펌프의 유동특성

Abstract

A jet pump is a fluid delivery device which spouts fluid of high pressure from a driving pipe and absorbs fluid of high pressure whose pressure is increased through exchange of momentum with surrounding gas of low pressure. As it has no mechanical movement, failure is rarely found. It is extensively applied for various types of industries and construction such as heat engines, fluid mechanical power stations, air-conditioning duct, chemical and petroleum chemistry, food and environment industry in that it provides smooth operation in absorbing solid as well as fluid and gas. Jet pumps can be easily constructed and installed irregardless of size of systems, can be easily used at the places involved in fluid and have little need of maintenance, and its expense is reasonable. Therefore, this study aims at presenting basic data to apply the whole jet pumps that will be used for mechanical devices or constructional equipments as alternative devices of pumps or mechanical devices instead of simple compression or vacuuming devices. For the purpose, it presents optimalization design by analysing what can not be obtained through experiments to evaluate improved or new performance of the device, analyses general contents of flow by acquiring exact test data on specific interpretative areas using more advanced experimental techniques, and identifies flow characteristics of jet pumps by examining validity of experiments using computer hydrodynamics to demonstrate the experiment. (1) At 90°, the influence of turbulence viscosity was extended to the expanded tube through the absorption duct, which indicates that fluid absorption of the pump affected decreased flow quantity efficiency. (2) In respect to static pressure distribution, this study found that negative pressure occurred at rounded part of the branch duct . It is thought that when the fluid was absorbed from the absorption tube to the expanded duct, the points attached by eddy flow were found due to changed speed and its direction (3) At 45°, the static pressure distribution had negative value, and when it was found that eddy flow increased due to increased absorption speed, this study suggests that the condition of curvature design for absorption tube in respect to further speed conditions should be considered important. (4). When turbulence momentum energy increased, dissipation value also increased and energy loss was found. As such energy loss was involved in temporary thermal movement of molecules through transformation of internal energy, it was found that the dissipation was related to the equation of viscosity. To decrease the energy loss, this study suggests that we have to find a configuration of nozzle and optimal points from the points when energy value of turbulence movement increased. (5). It was found that there was a difference in speed between upper and lower parts of the expanded ducts. It was because the speed value of the place near to the wall had smaller value than the opposite due to absorption according to different angles of absorption duct, but the farther from the wall, the speed vector value returned to increased value, which contributed to increased flow quantity efficiency. That is, it was found that the width of recovery increased, as flow velocity of absorbed flow quantity increased. (6). The extinction of the full pressure distribution value was smaller due to absorption at y / Dh > 0.5 than that of the opposite, but the nearer to the wall and faster, negative pressure was generated. It was thought because the flow absorbed caused eddy flow by shearing force of the wall. As such case caused flow quantity efficiency to decrease, this study suggests that proper locations should be selected to realize nozzle configuration at the expanded tube after the driving engine duct, which will contribute to least flow quantity loss.