• Journal of computational fluids engineering
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• v.16 no.3
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• pp.1-7
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• 2011

As a preliminary design study to achieve target aerodynamic performance, this work was conducted on an original nozzle with 9 flutes in order to design a fluted nozzle with 12 flutes. The thrust and rolling moment of the nozzle with 12 flutes were analyzed using a CFD code according to the depth and rotation angle of the flutes. Based on this, a fluted nozzle with 12 flutes was optimized to yield the same thrust as that of the original nozzle with 9 flutes. The response surface method was applied for shape optimization of the fluted nozzle and design variables were selected to determine the depth angle and rotation angle of the flutes. An optimized shape that led to a thrust as strong as that of the original nozzle was obtained.

• Journal of ILASS-Korea
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• v.17 no.3
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• pp.140-145
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• 2012

Recent common-rail injector of a diesel engine needs more smaller nozzle hole to meet the stringent emission regulation. But, small nozzle hole diameter can cause nozzle coking which is occurred due to the deposits of post-combustion products. Nozzle coking has a negative effect on the performance of fuel injector because it obstructs the fuel flow inside a nozzle hole. In this study DFSS (Design for six sigma) method was applied to find the effect of nozzle design parameter on nozzle coking. Total 9 injector samples were chosen and tested at diesel engine. The results show that nozzle hole diameter and K-factor have more effect on nozzle coking than A-mass and hole length. Large hole diameter and A-mass, small hole length and K-factor give more positive performance on nozzle coking in these experimental conditions. But, a performance about nozzle coking and exhaust gas emission shows the opposite tendency. Further study is needed to find the relation between nozzle coking and emission characteristic for the optimization of injector nozzle design.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.61-65
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• 2011

In this paper, the nozzle design with asymmetric configuration using the optimal method is used in order to improve the under- and over-expansion problem of the flow at the supersonic turbine nozzle. For the design of nozzle contour, 8 design variables are selected and the total-to-static efficiency from the nozzle inlet to the wake outlet is considered as the objective function to be maximized. The Fluent6.3 and the iSIGHT-FD program are used for calculation of nozzle flow and design optimization respectively. RBF(Radial Basis Function) method is chosen for approximate optimization algorithm. It is shown that the static efficiency of improved nozzle design increases 1.35% and loss coefficient decreases 19.85% as compared to baseline design.

• Journal of computational fluids engineering
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• v.2 no.1
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• pp.66-72
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• 1997

Optimum nozzle design exploiting the method of characteristic(M.O.C) has been in application as an efficient design methodology targeting a less weighted and short expansion nozzle. This paper treats the optimum nozzle design and the analysis of the inviscid compressible flow inside. Based on traditional Rao's method, the optimum nozzle design is coded with minor modifications for the identification of the control surface across which the mass flux should be conserved. Internal flow field is simulated numerically by M.O.C and implicit/explicit Taylor-Galerkin finite element method(F.E.M) with the aid of adaptive remeshing to capture the shock wave, hence improve the accuracy. Designed and calculated flow fields due to the separate analyses show that the mass flux predicted by optimum nozzle design with M.O.C is not conserved across the control surface and the sonic line should be located upstream of the nozzle throat. Rao's optimum nozzle design methodology exaggerates the momentum thrust and tends to overemphasize the engine performance loss.

• Journal of the Semiconductor & Display Technology
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• v.21 no.2
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• pp.38-44
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• 2022

Plasma density in semiconductor fabrication equipment becomes higher to achieve the improved the throughput of the process, but the increase of surface corrosion of the ceramic coated chamber wall has been observed by the increased plasma density. Plasma chamber wall coating with aerosol deposition prefer to be firm and uniform to prevent the potential creation of particle inside the chamber from the deformation of the coating materials, and the aerosol discharge nozzle is a good control factor for the deposited coating condition. In this paper, we investigated the design of the nozzle of the aerosol deposition to form a high-quality coating film. Computational fluid dynamics (CFD) study was employed to minimize boundary layer effect and shock wave. The degree of expansion, and design of simulation approach was applied to found out the relationship between the divergence angle and nozzle length as the key parameter for the nozzle design. We found that the trade-off tendency between divergence angle and nozzle length through simulation and quantitative analysis, and present the direction of nozzle design that can improve the uniformity of chamber wall coating.

• International Journal of Aeronautical and Space Sciences
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• v.7 no.1
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• pp.27-42
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• 2006

A method to design the contour and conception of a plug nozzle of arbitrary shape, but specified exit flow conditions is presented. Severals shapes can be obtained for exit Mach number by changing the specific heats ratio. The characteristics of the nozzle in terms of length, weight and pressure force exerted on the wall are compared to the Minimum Length Nozzle and found to be better. Our field of study is limited to the supersonic mode to not to have the dissociation of the molecules. The design method is based on the use of the Prandtl Meyer function of a perfect gas. The flow is not axial at the throat, which may be advantageous for many propulsion applications. The performance benefits of the plug nozzle compared to the Minimum Length Nozzle are also presented.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.05a
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• pp.335-338
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• 2010

A recent study for tracing the profiles of supersonic axisymmetric Minimum Length Nozzle with uniform and parallel flow at the exit section, the stagnation temperature is taken into account. The aim of this work is to add optimization algorithm to the supersonic nozzle design in order to get the optimum nozzle shape. The comparisons of the nozzle contours based on the method of characteristics are presented. The specific heats and their ratio vary with the stagnation temperature when this temperature of a perfect gas increases. An application is made for air in a supersonic nozzle.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.7
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• pp.97-104
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• 2021

LASOX is a cutting technology used to dismantle nuclear power plants. The core component of the laser-assisted oxygen hybrid cutting process is the supersonic nozzle. To design optimized supersonic nozzles, an experimental design was established and computational fluid dynamics was used to analyze the supersonic nozzles. The main factors affecting the supersonic nozzle performance were identified using Minitab. Further, the correlations and interactions between the main factors of the supersonic nozzle design were analyzed. The fluid analysis results were examined for the major factors and standardized response variables as well as main effects to ensure suitability of the supersonic nozzle design for the laser-assisted oxygen cutting process.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.3
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• pp.41-47
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• 2013

This study was carried out to improve the design of fuel injection nozzle for marine medium speed diesel engine. For this purpose, fuel injection nozzle was modeled and simulated using CATIA V5R19 and FLUENT & MSC Nastran. Analyses of flow and heat transfer, respectively, were performed to find the optimal design of fuel injection nozzle. As the results, big pressure drop, which may lead to cavitation damage, was occurred at inlet of fuel injection hole with diameter 0.3mm. Furthermore, it was confirmed that the increase of mean temperature of fuel injection nozzle was almost a half in comparison with that of fuel injection nozzle tip.

• Journal of ILASS-Korea
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• v.23 no.4
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• pp.205-211
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• 2018

Y-jet nozzle has various advantages over other twin-fluid nozzles and are used in industrial boilers. However, it costs large energy consumption because of assisted air and its design is complex. The Y-jet nozzle is consisted of a liquid and gas port and a mixing chamber. The diameter of the port and the length of the mixing chamber greatly affect spray and atomization characteristics, therefore, they are the most important factors in nozzle design. In this study, The experimental setup is consisted of a laboratory scale spray system. The characteristics of the Y-jet nozzle according to the design parameters were observed. As a result, it was found that the length of the mixing chamber did not have effect on the flow rate and the choking condition. The droplet size was measured using a Malvern type measuring device. In addition, measurements were conducted in the front and the right directions of the nozzles. Based on the results, the SMD View Ratio is defined. It is the asymmetrical design characteristics of the Y-jet nozzle.