Eunju Jeong

Mixing and Penetration Studies of Transverse Jet into a Supersonic Crossflow

A non-reacting experimental study on a normal injection into a Mach 1.92 crossflow which flows over various geometries (flat plate, small cavity, large cavity) was carried out to investigate the effect of the momentum flux ratio (J). The aft ramp of the cavity advances the increase of the penetration height and the strong two-dimensional shock from recompression region mainly affects the shock structure and mixing layer at the downstream flow. As flow runs downsward, the transverse penetration height increases with increasing J (J = 0.9, 1.7, 3.4). However, above some critical ratio, jet penetration height growth with increasing J is not appeared in flow-field. Large scale cavity has a good mixing efficiency but it increases the drag loss in the combustor.

Numerical Study on Combustion Process of Model Scramjet Engine with a Backward Step

A numerical study was carried out to investigate the combustion phenomena in a model Scramjet engine, which had been experimentally studied at the University of Tokyo using a high-enthalpy supersonic wind tunnel. The main airflow was 2.0 in Mach number and the total temperature of hot flow was 1800K. Equivalence ratio was set to be rather higher value of 0.26 than that of experiment to investigate the effect of strong precombustion shock. The results showed that selfignition occurred at the rear bottom wall of the combustor and combined with the shear layer flame between fuel jet and main airflow. Then, precombustion shock was generated at the step location and reversely enhanced the mixing and combustion process behind the shock. Due to the high equivalence ratio, the precombustion shock moved upstream of the step compared with that of experiment.

Numerical Simulation of Hypervelocity Flow on Hemisphere in T2 Shock Tunnel

Numerical simulations are thoroughly carried out for the flows in the nozzle and the test section in the T2 shock tunnel facility. In order to solve the flow realistically, an unsteady, axisymmetric, and nonequilibrium flow solver is employed. The thermochemical states of the gas are described by a four-temperature model. Obtained temperatures are compared with the experimental data measured by Palma using a Planar Laser-Induced Fluorescence (PLIF) Imaging technique.

Numerical Simulation Study of Supersonic Combustion in Model Combustors

Air-fuel mixing and flame-holding are two important factors that have to be considered in the design of an injection system. Different injection strategies have been proposed with particular concern for rapid air-fuel mixing and flame-holding. Two representative injection techniques can be applied in a supersonic combustor. One of the simplest approaches is a transverse(normal) injection. The cavity flame holder, an integrated fuel injection/flameholding approach, has been proposed as a new concept for flame holding and air-fuel mixing in a supersonic combustor. This paper describes numerical efforts to characterize the flameholding and air-fuel mixing process of a model scramjet engine combustor, where hydrogen is injected into a supersonic cross flow and a cavity. The combustion phenomena in a model scramjet engine, which has been experimentally studied at University of Queensland and Australian National University using a free-piston shock tunnel, were observed around the separation region of the transverse injector upstream and the inside cavity. The results show that this flow separation generates recirculation regions which increase air-fuel mixing. Selfignition occurs in the separation-freestream and cavity-freestream interfaces.