분사펌프의 수직 흡입관로와 구동관로의 위치변화에 대한 유동특성 연구

Abstract

ABSTRACT

A Study on the Flow Characteristics of Jet Pump by Vertical Suction Pipe and Position of Driving Pipe

Kim Noh-Hyeong Advisor : Prof. Lee Haeng-Nam, Ph.D. Department of Mechanical Engineering Graduate School of Chosun University

A jet pump is a fluid carrying device which spouts fluid of high pressure from a driving engine pipe and absorbs fluid of high pressure whose pressure is increased through exchange of momentum with surrounding gas of low pressure. It is applied for various types of industries such as heat engines, water power and thermal power plants, ducts for air conditioning, chemical and petroleum chemistry, food and environment industry in that it provides smooth operation in absorbing solid as well as fluid and gas. Vapor-vapor jet pump are widely used for absorption, mixing and dehydration in industrial fields and fluid-gas jet pumps have been considered most important for air conditioners to control a variety of harmful gases and to create pleasant environment of structures. Jet pumps can be easily constructed and installed regardless 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. This study is to identify floating characteristics of jet pumps, mean velocity, distribution of total pressure through CFD analysis. For the purpose, it changed the ends of driving pipe with diameter ratio of 1 : 1.9, 1 : 2.25 and 1 : 3.25 found optimal points of driving engine pipes in each diameter ratio and conducted the analysis through PIV experiment. The results are presented as follows: (1) As increase an entrance condition of velocity was fast and fluid efficiency suck in vertical suction pipe was higher. (2) When the ends of each driving pipe with diameter ratios of 1 : 1.9, 1 : 2.25 and 1 : 3.25 were placed in 1.133, 1.213 and 1.333, the largest effect of absorption was found, but the effect was not related to velocity change. (3) Flux efficiency decrease as diameter of driving pipe increases, and it increases as Reynolds number increases. (4) When the end of driving pipe was located in the center of the vertical suction pipe, average 11% of efficiency decreased compared to the case that it was placed at the optimal point. When it was extended over optimal point, mean 23% of efficiency deceased. As the driving pipe was longer, flow quantity efficiency was lower, and when the end of driving pipe was placed at optimal point, flow quantity efficiency was the best. (5) When suction occurs at vertical suction pipe, vortex that is formed at the joint of driving pipe with curvature and expanded pipe increases as velocity increases. (6) In measuring PIV, as Reynolds number increases because of influence of shearing force of wall, vortex of velocity vector is formed near the wall. (7) To increase suction efficiency, nozzle configuration should be realized at proper place of expanded pipe as a means to decrease dissipation of energy.