Yang-Ji Lee

Effects of Fuel Injectors and Cavity Configurations on Supersonic Combustion

In this study, the effects of the diameter and quantity of fuel nozzles combined with various cavity-type flame holders for supersonic combustion were investigated empirically and numerically. Although increasing the quantity of fuel nozzles yields a greater fuel-to-air interface area, which results in a higher fuel–air mixing rate, smaller nozzle diameters yield a lower penetration depth, which results in a lower combustion performance at the top wall region. This study adopts the cavity shapes of fuel injectors from previous research studies to design new injector configurations with different sizes and quantities of fuel nozzles. The diameter and quantity of nozzles are determined to have the same equivalence ratio and momentum ratio as were used in previous research under a given fuel pressure. A comparison of results from the present tests with previous research shows that the plain cavity and zigzag cavity have distinct characteristics. Configurations using these cavity types were investigated via t...

Design Study of a Dual-Mode Ramjet Engine with Large Backward-Facing Step

Scaled model of a dual-mode ramjet engine with large backward-facing step, as a component of the rocket-based combined cycle engine, was designed. Design parameters were derived for this engine with the consideration of application for the rocket-based combined cycle engine. Design methodology was established for these design parameters. The design was partially verified through numerical study. Flow characteristics of the dual-mode ramjet engine with large backward-facing step was investigated experimentally. The design methodology for relevant design parameters established in this study was verified as feasible.

Combustion Test of a Mach 5 Scramjet Engine Model

Combustion tests were conducted for a hydrogen-fueled Mach 5 scramjet engine model using a blow-down facility. No fuel and two fuel flow rate cases were tested for two different model configurations. Time history of the wall static pressures inside the model and their time-averaged spatial distribution were used for the analysis of the flow and combustion characteristics. For shorter model, supersonic combustion was occurred for both of the fuel flow rate cases. For longer model, supersonic combustion was occurred for less fuel case, whereas thermal choking and subsonic combustion were occurred for more fuel case. Intake started even for this subsonic combustion case.

A Starting Characteristics Study of the Scramjet Engine Test Facility with a Mach 5.0 Nozzle

A Mach 5 nozzle and a diffuser of the Scramjet Engine Test Facility (SETF) were made for a hydrocarbon-fueled scramjet engine. SETF, attached with a diffuser guide, started with a model of 60% blockage, though the model engine could not start by over expansion of the facility nozzle. The model was moved into the nozzle to escape the shock generated from the nozzle exit, both SETF and the engine could start. The pitot rake experiments (blockage of 2.3%) were done for measuring the core flow in the test section. From the pitot experiments, the core flow was expanded by an under expansion. It means that the core flow in the test section was related with a model blockage. SETF and the engine with a blockage of 33% work normally. From a series of experiments, SETF started with a normal shock efficiency of 58%, regardless of a blockage ratio.