• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2007.11a
• /
• pp.159-162
• /
• 2007

The characteristic of air-assist spray injected into subsonic crossflow were studied experimentally. External-mixing air assist injector of Orifice nozzle with L/d of 3 were tested with various air-liquid ratio. Shadowgraph photography was performed for spray visualization and trajectory of spray measurements. The detailed spray structure was characterized in terms of SMD, velocity, and volume flux, using PDPA. Experimental results indicate that penetration length was increased and spray distribution was accelerated by increasing air-liquid ratio.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.25 no.1
• /
• pp.29-41
• /
• 2021

The PID controller with fin angle and thrust as control input was designed based on the aerodynamic data of scramjet system. Flight simulation following a given trajectory which strike the target point after climb and cruise with constant dynamic pressure was conducted. After that, the required thrust for the climb and cruise was calculated and the required fuel flow rate for the hydrogen fuel dual mode scramjet combustor was analyzed. The combustor analysis of this study which conducted on integrated model of independently developed inlet, combustor, nozzles and external aerodynamic models, laying the foundation for the integrated design of the air breathing hypersonic system.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.8 no.1
• /
• pp.16-26
• /
• 2004

The objective of this study is to apply preconditioning to Wavier-Stokes equations with a turbulence model. The concept of a pseudo sonic speed was adopted. Roe's FDS was used for spatial discretization, LU-SGS scheme was used for time integration. In order to test the algorithms, the low speed flows around NACA airfoils and the flows through supersonic nozzle were calculated. The algorithm developed in the present study shows good performance in the calculations of low speed viscous flows and supersonics flows.

• Journal of computational fluids engineering
• /
• v.5 no.2
• /
• pp.47-54
• /
• 2000

A robust Navier-Stokes code has been developed to efficiently predict hypersonic flows in chemical nonequilibrium. The HLLE+ flux discretization scheme is used to improve accuracy and robustness of hypersonic flow analysis. An efficient LU approximate factorization method is also used to solve the flow equations and species continuity equations in fully coupled fashion to implicitly treat stiff source terms of chemical reactions. The HLLE+ scheme shows lower grid dependency for the wall heating rates than other schemes. The developed code has been used to compute chemical nonequilibrium air flow through expanding hypersonic nozzle and past two and three dimensional blunt-nosed bodies. The results are in good agreement with existing numerical and experimental results.

• Proceedings of the KSME Conference
• /
• 2003.11a
• /
• pp.986-991
• /
• 2003

A turbulent wake generated by a cylinder in nozzle contraction affects to the jet flow characteristics. In this study, a computational work to investigate the effect of the turbulent wake on two-dimensional subsonic jet was carried out with three different kinds of nozzle. Computations are applied to the two-dimensional unsteady, Navier-Stokes equations. Several kinds of turbulent models and wall functions are employed to validate the computational predictions. It was known that the wake flow enhanced the spread of the jet flow, compared with no wake flow condition. It was also found that the jet core is shortened by the wake flow developed from a control cylinder.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2004.10a
• /
• pp.62-67
• /
• 2004

This paper investigates the off-design performance of methane-fueled air turbo ramjet(ATR) engine in subsonic flight speed range. The ATR engine was modeled and simulated numerically. Each component was modeled to enable their off-design calculation. Compressor operating point was determined by flow matching with nozzle, and turbine by work matching. The ATR engine exhibited quite different off-design behavior compared to the conventional gas turbine engine.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.35 no.2
• /
• pp.153-160
• /
• 2011

The characteristics of supersonic coaxial/off-axis jet impingements on a slanted kerf surface were experimentally studied, to investigate the role of the assist gas that removes molten materials from cut zone formed by laser machining. In this parametric study, hundreds of high-resolution schlieren images were obtained for various gas pressures, distances between nozzle exit and kerf surface, kerf widths, and alignments of off-axis nozzle. It was noticed that simply increasing the assist gas pressure was not effective in eliminating the flow separation that occurs downstream of the kerf surface. However, it was also observed that by increasing the kerf width and utilizing off-axis nozzles, the separation of the assist gas on the kerf surface can be weakened. The effect of the distance between the nozzle exit and the kerf surface on the characteristics of separation occurring on the kerf surface was found to be lower in the case of supersonic nozzles than that in the case of sonic nozzles.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.41 no.10
• /
• pp.779-787
• /
• 2013

The effects of various nozzle configurations on infrared signature are investigated for the purpose of analysing the infrared signature level of aircraft propulsion system. A virtual subsonic aircraft is selected and then a circular convergent nozzle, which meets the mission requirements, is designed. Convergent nozzles of different configurations are designed with different geometric profiles. Using a compressible Navier-Stokes-Fourier CFD code, an analysis of thermal flow field and nozzle surface temperature distribution is conducted. From the information of plume flow field and nozzle surface temperature distribution, IR signature of plume and nozzle surface is calculated through the narrow-band model and the RadThermIR code. Finally, qualitative information for IR signature reduction is obtained through the analysis of the effects of various nozzle configurations on IR signature.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.5 no.1
• /
• pp.10-17
• /
• 2001

In this paper are presented main power and gasdynamic characteristics of hypersonic test cell of Research Test Center (RTC) of Central Institute of Aviation Motors (CIAM). The distributions of temperature and Mach number at the exit of the aerodynamic nozzle of test cell are received at simulation conditions of flight at Mf=6. Values of available pressure difference and throttling characteristics for various operational modes of test cell, including the loading of working section by Scramjet model without the heating of air at entrance to the aerodynamic nozzle and with the heating of air, are received too.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.36 no.8
• /
• pp.774-779
• /
• 2008

An experimental study on the micro-supersonic jet flow fields has been carried out. A sonic nozzle of 440 ${\mu}m$-exit diameter and a Laval nozzle of 800 ${\mu}m$ exit diameter with the nozzle exit Mach number 2.0 were fabricated by stretching a micro Pyrex glass tube for the present experiments. Schlieren flow visualization and Pitot pressure distribution of the jet flow field were obtained. Representative characteristics of the jet flow fields such as, supersonic length, jet core length, similarity of the velocity field, and jet spreading rates, have been observed. All the results were compared to previous observations of larger supersonic jets of higher Reynolds numbers, and it was found that overall characteristics of the micro supersonic jet are qualitatively similar as those of the higher Reynolds number jets, except the jet core length and the jet spreading rate.