• Title/Summary/Keyword: Impinging Land

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The Effect of Impinging Land Size on Diesel Spray Behavior in OSKA Type Combustion Chamber (OSKA형 연소실에서 충돌면크기변화가 디젤분무거동에 미치는 영향)

  • 임덕경;박권하
    • Transactions of the Korean Society of Automotive Engineers
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    • v.9 no.4
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    • pp.18-26
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    • 2001
  • OSKA engine was developed to remove the dense core of injection sprays. The engine uses impinging spray on a small pip, which spray after impinging is broken into smaller drops and disperses into fee space in chamber. In this paper the pip size is analyzed to give more dispersion of spray and fuel vapor. The gas phase is modelled by the Eulerian continuum conservation equations of mass, momentum, energy and fuel vapour fraction. The liquid phase is modelled following the discrete droplet model approach in Lagrangian form, and the droplet wall interaction is modelled as a function of the velocity normal to impaction lands. The droplet distributions, vapor fractions and gas flows are analyzed for various injection pressure cases. Numerical results indicate that the land diameter of 5.6mm has the best performance of spray dynamics and vaporization in the test sizes.

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Numerical Analysis of Geometric Effects on Spray Characteristics in Small Direct-injection Diesel Engines (소형디젤기관 내 충돌부의 기구학적 조건에 대한 분무특성의 수치적 해석)

  • 류성목;차건종;김덕줄;박권하
    • Transactions of the Korean Society of Automotive Engineers
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    • v.7 no.5
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    • pp.55-65
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    • 1999
  • Many researches have been investigating small direct-injection diesel engines using the spray impacting on walls. Those systems have one or more raised pips to break-up the fuel and spread it widely toward a desired direction in a combustion chamber. In this study, the sizes and heights of the pips are determined by using a computational fluid dynamics code employing non-orthogonal grid systems. In order to find out the suitable pip-shape to a small chamber, the spray behaviors, occupied spary volumes and averaged droplets sizes are calculated with the variation of shape of the pip, such as, size and heights and inclined degree. The desired shape of the impinging land is proposed for the design of combustion system in small diesel engines.

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A Study on Signal Parameters Estimation via Nonlinear Minimization

  • Jeong, Jung-Sik
    • Journal of Navigation and Port Research
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    • v.28 no.4
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    • pp.305-309
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    • 2004
  • The problem for parameters estimation of the received signals impinging on array sensors has long been of great research Interest in a great variety of applications, such as radar, sonar, and land mobile communications systems. Conventional subspace-based algorithms, such as MUSIC and ESPRIT, require an extensive computation of inverse matrix and eigen-decomposition In this paper, we propose a new parameters estimation algorithm via nonlinear minimization, which is simplified computationally and estimates signal parameters simultaneously.

A compensation method for the scaling effects in the simulation of a downburst-generated wind-wave field

  • Haiwei Xu;Tong Zheng;Yong Chen;Wenjuan Lou;Guohui Shen
    • Wind and Structures
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    • v.38 no.4
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    • pp.261-275
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    • 2024
  • Before performing an experimental study on the downburst-generated wave, it is necessary to examine the scale effects and corresponding corrections or compensations. Analysis of similarity is conducted to conclude the non-dimensional force ratios that account for the dynamic similarity in the interaction of downburst with wave between the prototype and the scale model, along with the corresponding scale factors. The fractional volume of fluid (VOF) method in association with the impinging jet model is employed to explore the characteristics of the downburst-generated wave numerically, and the validity of the proposed scaling method is verified. The study shows that the location of the maximum radial wind velocity in a downburst-wave field is a little higher than that identified in a downburst over the land, which might be attributed to the presence of the wave which changes the roughness of the underlying surface of the downburst. The impinging airflow would generate a concavity in the free surface of the water around the stagnation point of the downburst, with a diameter of about two times the jet diameter (Djet). The maximum wave height appears at the location of 1.5Djet from the stagnation point. Reynolds number has an insignificant influence on the scale effects, in accordance with the numerical investigation of the 30 scale models with the Reynolds number varying from 3.85 × 104 to 7.30 × 109. The ratio of the inertial force of air to the gravitational force of water, which is denoted by G, is found to be the most significant factor that would affect the interaction of downburst with wave. For the correction or compensation of the scale effects, fitting curves for the measures of the downburst-wave field (e.g., wind profile, significant wave height), along with the corresponding equations, are presented as a function of the parameter G.

Signal Parameters Estimation in Array Sensors via Nonlinear Minimization. (비선형 최소화 방법을 이용한 수신신호의 파라미터 추정알고리즘에 관한 연구)

  • Jeong, Jung-Sik;Park, Sung-Hyeon;Kim, Chul-Seung;Ahn, Young-sup
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • 2004.04a
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    • pp.305-309
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    • 2004
  • The problem for parameters estimation of the received signals impinging on array sensors has long been of great research interest in a great variety of applications, such as radar, sonar, and land mobile communications systems. Conventional subspace-based algorithms, such as MUSIC and ESPRIT, require an extensive computation of inverse matrix and eigen-decomposition. In this paper, we propose a new parameters estimation algorithm via nonlinear minimization, which is simplified computationally and estimates signal parameters simultaneously.

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