Characterization of Ejector Effect-Induced Flow Dynamics in Semi-Enclosed Engine Test Cells

A computational study with analytical validations was conducted to analyze flow relations surrounding the process of the ejector effect. The ejector effect is a phenomenon where a high velocity core mass flow exhausts from a nozzle into an exhaust duct or mixing chamber, entraining surrounding ambient fluid. Four main flow cases are presented to be investigated within the computational study, each of which systematically increases in complexity. The cases all have the same domain, with a colinear nozzle and exhaust duct. To increase complexity, boundary conditions are changed. Starting from a fully freestream condition, then changing the vertical boundaries to no-slip walls and finally changing the wall aft the exhaust duct to form the semi-enclosed testing cell. The intermediate tests are currently ongoing. Through computational analysis and analytical relation of the nozzle plumes, it is observed that the half-value width (vertical location of the plume where the velocity is half of the axial velocity) is an important parameter, as if the exhaust duct is set to be between the half width diameter and twice the half width diameter, the nozzle exhaust will be effectively ventilated from the testing cell.