• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.5
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• pp.19-28
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• 2017

Effects of cavitation and hydraulic flip in circular and elliptical nozzles on the flow characteristics have been studied. Spray tests were conducted using injectors with different ratios of an orifice length(L) to a diameter(d) and of a major axis diameter(a) to a minor axis diameter(b). With the increment of an injection pressure drop, discharge coefficients slightly decreased in cavitation flows, and those suddenly dropped and were almost constant in hydraulic flip flows. For elliptical nozzles with L/b > 8 and L/a < 8, discharge coefficients and flow patterns showed different results from those in previous circular nozzles. When a flow in the elliptical nozzle was under steady condition, as the liquid column went downstream from the nozzle, its spray angle a little decreased in the plane of a major axis and increased in the plane of a minor axis.

• Journal of the Korean Society of Propulsion Engineers
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• v.3 no.3
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• pp.31-39
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• 1999

In this paper, numerical experiment is attempted to analyze and compare the combustion efficiency of the burning sprays due to OFO, FOF triplet / FOOF split doublet injectors. Preconditioned Wavier-Stokes equation system with low Reynolds number $\kappa$-$\varepsilon$ model for turbulence closure, is LU-SGS time-integrated. Spray processes are modeled by DSF analysis with experimentally determined injection characteristics. n-heptane/air global reaction model approximates the combustion for simplicity, and the influence of turbulence on the chemical reaction is included using eddy dissipation model. The results showed the FOF triplet injector of highest combustion efficiency, whereas the OFO type of poet performance. It was also observed that the droplet mean diameter and the average gas temperature due to the mixing efficiency, are the representative parameters for the performance design of combustion.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.544-549
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• 2017

This paper aims to examine the effect of rotational fluid motion about the efficiency of the gas - liquid ejector, which is a core unit in a ship equilibrium water treatment system. The ejector is a device for injecting ozone into ship equilibrium by the negative pressure generated by exchange of momentum between water and ozone. The existing ejector ejects the driving fluid with a simple form. In this paper, however, a rotation induction device is applied to the driving nozzle so that the driving fluid can be rotated and injected. To investigate the flow characteristics by the rotational movement of the driving fluid, CFD was used. The pressure and flow rate of the driving fluid, the negative pressure and suction flow rate of the suction fluid in the suction part, and the discharge pressure were predicted. On the basis of the results, the efficiency of the ejector using the rotation induction system was 22.25%, which was about 1.7% better than that of the existing ejector. Finally, to verify the feasibility of the CFD, an experiment was conducted on the ejector using the rotation induction device and the results were similar to those of the CFD.

• Journal of the Korean Society of Propulsion Engineers
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• v.8 no.2
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• pp.10-17
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• 2004

The results of the combustion performance tests of gas generator which supplies hot gas into the turbine of turbo-pump for liquid rocket engine and uses LOx and kerosene as propellant are described. The gas generator consists of a injector head with F-O-F impinging injector, a water cooled combustion chamber, a gas torch igniter, a turbulence ring and an instrument ring. The effect of turbulence ring and combustion chamber length on performance of gas generator are investigated. The ignition and combustion at design point are stable and the pressure and gas temperature at gas generator exit meets the target. The turbulence ring installed at middle of chamber effectively mixes hot gas with cold gas and the effect of residence time of hot gas in gas generator on combustion efficiency is small. Test results show that the main parameter controlling the gas temperature at gas generator exit is overall O/F ratio.

• Journal of the Korean Society of Propulsion Engineers
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• v.9 no.4
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• pp.48-54
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• 2005

An experimental study was carried out to investigate the effect of film cooling in the lab-scale liquid rocket engine using liquid oxygen(LOx) and Jet A-1(Jet engine fuel) as propellants. Film coolants(Jet A-1 and water) was injected through the film cooling injector. The outside wall temperature of the combustor and film cooled length were determined for chamber pressure, mixture ratio, and the different geometries(injection angle) with the percent film coolant flow rate. The loss of characteristic velocity was determined for the case of film cooling with water and Jet A-1. As chamber pressure increased, the outside wall temperature increased in the nozzle but unchanged over the 9 percent film coolant flow rate for the combustion chamber used in this study. Characteristic velocity wasn't affected with the mixture ratio over the 9 percent film coolant flow rate.

• Fire Science and Engineering
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• v.31 no.4
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• pp.59-64
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• 2017

In the present experimental study, the liquid pool fire extinguishment performance of twin-fluid nozzle was preliminarily examined. For the liquid pool fire, the ethanol of 1200 ml (volume) was prepared, and two kinds of air flow rate conditions (40 l/min and 70 l/min) were tested at the constant water flow rate condition of 632 ml/min. In the present experimental ranges, the fire extinguishment experiments were carried out using the twin-fluid nozzle and its spray characteristics (i.e., SMD (Sauter Mean Diameter) and flow distribution) were investigated. As a result, at the higher air flow rate, the liquid pool fire was extinguished quickly and successfully, which was discussed using the visualization and spray characteristics of twin-fluid nozzle. In addition, through the comparison with some of previous results, it was found that potentially, the twin-fluid nozzle can extinguish the liquid pool fire under the smaller water flow rate condition, as compared with the single-fluid nozzle.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.4
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• pp.81-88
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• 2013

It was designed and tested at the design point that an oxidizer rich preburner for a staged combustion liquid rocket engine propelled by kerosene and LOx. The oxidizer rich preburner was designed as some of LOx injected from the mixing head was burned with kerosene and the rest of LOx injected from injection holes in the regenerative cooling chamber was vaporized by combustion gas. The preburner is operated at OF ratio of 60 and combustion pressure of 20 MPa. The Preburner has a honey-comb type mixing head with simplex swirl injectors, a turbulence ring improving combustion stability and uniformity of product gas temperature distribution, and a nozzle simulating the duct. With the combustion test results at the design point, the oxidizer rich preburner showed high combustion stability and uniformity of product gas temperature distribution.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.1
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• pp.17-25
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• 2017

An experimental study was performed for the combustion-field visualization of the burner which burns the liquid hydrocarbon fuel atomized by an ultrasonic oscillator. Configurations of the flame and temperature gradient were caught by both high-speed camera and thermo-graphic camera, and those images were analyzed in detail through a post-processing. In addition, the fuel consumption was measured using the balance during the combustion reaction. As a result, the consumption of atomized fuel increased with the increasing flow-rate of carrier-gas, but any correlation between the air/fuel ratio and carrier-gas flow-rate was not found at the low flow-rate condition. Also, the combustion-field grew and reaction-temperature rose due to the strengthening of combustion reaction with the increasing flow-rate of carrier-gas and power consumption of ultrasonic oscillator.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.6
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• pp.28-38
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• 2019

To investigate the relation between flame structure and combustion dynamic characteristics in bi-swirl coaxial injectors for a liquid rocket engine, combustion experiments were performed using gaseous methane and gaseous oxygen. CH* radicals and pressure fluctuations were simultaneously measured by changing the injector geometries such as recess length/orifice diameter and the flow conditions such as equivalence ratio/oxidizer mass flow rate. As the injector geometries affected the velocities and mixing of the propellants, the change in flame structures was observed. From a result of the frequency analysis, it was confirmed that combustion dynamic characteristics varied according to the injector geometry/flow condition and combustion instabilities could occur under specific recess length/flow conditions.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.1
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• pp.36-44
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• 2012

Multi-injector rocket engine using high-concentrated hydrogen peroxide and kerosene was designed and manufactured. Design requirements of a rocket engine were determined and main geometrical parameters of rocket engine were determined on the basis of fundament. Six coaxial swirl injectors were mounted on the multi-injector engine. Flow analysis in the hydrogen peroxide manifold was performed to minimize stagnation and recirculation zones. Finally, the optimized hydrogen peroxide manifold was manufactured and cold flow test was carried out to confirm mass flow rate per uni-element, spray pattern and atomization characteristics. The results of cold flow test showed that the mixing head design process was successful and enough to use as a essential database for the development of a full-scale engine.