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Computational study of flow separation in truncated ideal contour nozzles under high-altitude conditions

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International Journal of Fluid Engineering

International Journal of Fluid Engineering 2024年第1期 21-30页

作者： Ijas Muhammed V V Shamsia Banu N abhilash suryan Vincent Lijo David Simurda Heuy Dong Kim College of Engineering Trivandrum Government Engineering College Thrissur Faculty of Mechanical Engineering Technical University of Liberec Andong National University

Flow separation in rocket nozzles has been studied mostly under sea-level conditions, which fail to take into account changes in ambient density and ambient pressure during the flight of a rocket. In the present study, numerical analysis is conducted of flow characteristics within a truncated ideal contour(TIC) nozzle to investigate the influence of ambient density and pressure on flow separation. Six different altitudes from a typical flight are considered, from a very low altitude to a high altitude. The flow is analyzed by varying the nozzle pressure ratios corresponding to these altitudes. Both cold flow and hot flow simulations are conducted. The locations of separation positions at various altitude conditions are accurately captured and are found to be in good agreement with experimental results. The results of the study establish that for a given nozzle pressure ratio, the flow separation point is shifted upstream with increasing altitude. This clearly points to a dependence of separation position on the altitude of operation for TIC rocket nozzles.

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Computational Study of Performance Characteristics for Truncated Conical Aerospike Nozzles

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Journal of Thermal Science 2017年第6期26卷 483-489页

作者： Prasanth P Nair abhilash suryan Heuy Dong Kim Department of Mechanical Engineering College of Engineering Trivandrum Department of Mechanical Engineering Andong National University

Aerospike nozzles are advanced rocket nozzles that can maintain its aerodynamic efficiency over a wide range of altitudes. It belongs to class of altitude compensating nozzles. A vehicle with an aerospike nozzle uses less fuel at low altitudes due to its altitude adaptability, where most missions have the greatest need for thrust. Aerospike nozzles are better suited to Single Stage to Orbit （SSTO） missions compared to conventional nozzles. In the cur- rent study, the flow through 20% and 40% aerospike nozzle is analyzed in detail using computational fluid dy- namics technique. Steady state analysis with implicit formulation is carried out. Reynolds averaged Navier-Stokes equations are solved with the Spalart-AUmaras turbulence model. The results are compared with experimental results from previous work. The transition from open wake to closed wake happens in lower Nozzle Pressure Ratio for 20% as compared to 40% aerospike nozzle.

关键词： aerospike nozzle plug nozzle advanced rocket nozzles thrust coefficient base pressure.

Experimental Study on the Inlet Fogging System Using Two-Fluid Nozzles

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Journal of Thermal Science 2010年第2期19卷 132-135页

作者： abhilash suryan Dong Sun Kim Heuy Dong Kim School of Mechanical Engineering Andong National University FMTRC Daejoo Machinery Co.

Large-capacity compressors in industrial plants and the compressors in gas turbine engines consume a considerable amount of power. The compression work is a strong fimction of the ambient air temperature. This increase in compression work presents a significant problem to utilities, generators and power producers when electric demands are high during the hot months. In many petrochemical process industries and gas turbine engines, the in- crease in compression work curtails plant output, demanding more electric power to drive the system. One way to counter this problem is to directly cool the inlet air. Inlet fogging is a popular means of cooling the inlet air to air compressors. In the present study, experiments have been performed to investigate the suitability of two-fluid nozzle for inlet fogging. Compressed air is used as the driving working gas for two-fluid nozzle and water at am- bient conditions is dragged into the high-speed air jet, thus enabling the entrained water to be atomized in a very short distance from the exit of the two-fluid nozzle. The air supply pressure is varied between 2.0 and 5.0 bar and the water flow rate entrained is measured. The flow visualization and temperature and relative humidity measurements are carried out to specify the fogging characteristics of the two-fluid nozzle.

关键词： Evaporative Cooling Inlet Fogging Energy Savings Two-fluid Nozzles

Mass Flow Prediction of the Coriolis Meter using C^0 Continuous Beam Elements

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Journal of Thermal Science 2015年第4期24卷 398-402页

作者： Binulal B R Akash Rajan abhilash suryan R Jayaraj Kochupillai Heuy Dong Kim Research Scholar Department of Mechanical EngineeringCollege of Engineering Trivandrum Department of Mechanical Engineering College of Engineering Adoor Department of Mechanical Engineering College of Engineering Trivandrum Department of Mechanical Engineering Andong National University

A three node C^0 continuous isoparametric beam element is formulated to model the curved pipe conveying fluid in three dimensional *** equations of motion for the combined structure and fluid domain including added mass effect,Coriolis effect,centrifugal effect and the effect of pressure on the walls of pipe have been developed by *** equation is converted to finite element formulation using Galerkin technique and is validated with the results available from literature.

关键词： Coriolis mass flow meter Timoshenko beams finite element formulation Coriolis effect

Computational study on flow through truncated conical plug nozzle with base bleed

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Propulsion and Power Research 2019年第2期8卷 108-120页

作者： Prasanth P.Nair abhilash suryan Heuy Dong Kim Department of Mechanical Engineering College of Engineering TrivandrumTrivandrum 695016India Department of Mechanical Engineering Andong National UniversityAndong 760749Republic of Korea

Conical plug nozzle and truncated conical plug nozzle are advanced rocket nozzles suitable for use as altitude compensating *** this study flow through the conical plug and truncated conical plug nozzles are numerically simulated to first validate with experimental data and then to compare the performance when a base bleed is *** numerical analysis has considered two-dimensional axisymmetric ***-averaged NavierStokes equations are solved with two equation shear stress transport k-ω turbulence *** the validation of the plug nozzle,flow features and wall pressure along the length of the nozzle is taken for different nozzle pressure *** the validation of truncated plug nozzle,flow features and base pressures at various nozzle pressure ratios are *** base bleed is taken as 2%of the inlet mass flow *** comparison of results shows that the introduction of base bleed helps to compensate for the loss of thrust due to conical plug nozzle truncation.

关键词： Plug nozzle Aerospike nozzle Advanced rocket nozzle Reynolds-averaged Navier-Stokes(RANS) Base pressure Coefficient of thrust Base bleed Secondary flow

Computational Study on the Influence of Number of Threads on the Perfor-mance of Single Screw Pump at High Angular Velocities

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Journal of Thermal Science 2017年第1期26卷 54-59页

作者： Jaison Philip abhilash suryan T.V Sanand P Unnikrishnan Nair S. Sivakumar Department of Mechanical Engineering College of Engineering Trivandrum Kerala India 695016 Turbo Pump Division LPSC Valiamala Trivandrum Kerala. Department of Mechanical Engineering Rajadhani Institute Engineering & Technology Trivandrum Kerala India

Fluid flow in a screw pump which rotates at very high angular velocity is numerically analyzed. In the present study, fluid flow in screw pumps under high Reynolds number, of the order of 105, is considered. Screw pump has two major elements, a plain shroud which is a stationary element and a rotating hub with helical grooves contained within the shroud. In this paper, three variants of hubs with different number of thread starts numbering six, eight and twelve in combination with a plain shroud is studied. Each of the three possible combinations are analyzed on the basis of pressure rise developed, efficiency and shaft power. It was seen that pressure rise, efficiency and shaft power increases as the number of threads increases in the range of mass flow rates studied.

关键词： Screw pump, Turbulent flow, Angular velocity

Numerical Simulation of Duct Flow with Fog Droplets

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Journal of Thermal Science 2010年第6期19卷 533-539页

作者： abhilash suryan J. K. Lee D. S. Kim H. D. Kim Department of Mechanical Engineering Andong National University FMTRC Daejoo Machinery Co.

Evaporative cooling is a widely used air cooling technique. In this method, evaporation of a liquid in the surrounding air cools the air in contact with it. In the current investigation, numerical simulations are carded out to visualize the evaporation and dynamics of tiny water droplets of different diameters in a long air duct. The effect of initial droplet size on the temperature and relative humidity distribution of the air stream in the duct is investigated. Three different initial conditions of air are considered to verify the influence of ambient conditions. Droplet spray patterns are also analyzed to identify the suitable locations for the spray nozzles within the duct. The resuits obtained are displayed in a series of plots to provide a clear understanding of the evaporative cooling process as well as the droplet dynamics within the ducts.

关键词： Evaporative cooling Fog droplet Two-phase flow Relative humidity

Computational Study on Aerodynamic and Thermal Characteristics of a Hot Jet in Parallel Flow

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Open Journal of Fluid Dynamics 2017年第3期7卷 348-358页

作者： Merlin C. Das Meribeni L. Jungio N. Haritha abhilash suryan Heuy Dong Kim Department of Mechanical Engineering College of Engineering Trivandrum Kerala India Department of Mechanical Engineering Andong National University Andong Korea

The study of the migration characteristics of turbulent jets has become relevant as they are used in a variety of engineering devices and are encountered in combustion, chemical processes, and processes involving cooling, mixing, and drying. In several applications, especially in the case of hot streaks in gas turbines, the knowledge of mixing phenomena becomes crucial from a design perspective. The purpose of this study is to look into the characteristics of a round hot jet in a parallel air flow. A jet of hot air injected through a nozzle into a flow of cold air has been considered. Numerical simulations were carried out with different hot jet temperatures and two different Reynold’s numbers, thus aiming at understanding the effect of initial conditions on the mixing of the jet. The temperature profiles were studied at different sections downstream of the nozzle. The results are presented in non-dimensional form.

关键词： Turbulent Jet Parallel Flow Reynold’s Number Temperature Profiles

Albumin use in cirrhosis:a nephrology viewpoint on key considerations and cautionary notes

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Hepatobiliary Surgery and Nutrition 2024年第3期13卷 536-539页

作者： abhilash Koratala Amir Kazory Division of Nephrology Department of MedicineMedical College of WisconsinMilwaukeeWIUSA Division of Nephrology Hypertension and Renal TransplantationUniversity of FloridaGainesvilleFLUSA

The constant need to reduce the variability of clinical practice and to improve the quality of care of the patients and their outcomes have led to the increasing emphasis on evidence-based *** there is a paucity of robust data on a specific topic or there are conflicting conclusions from available studies,clinical practice recommendations may prove helpful to fill the gap and assist with clinical *** are a variety of such recommendations,such as consensus statements,practice guidelines,and position statements,each with a specific set of methodology and *** statements are comprehensive documents meant to elucidate,justify,and recommend a particular approach to a clinical *** papers often present a detailed understanding of the issues in question,discuss the pros and cons of the available options,and provide the rationale for the position that is set *** other forms of clinical practice consensus,position statements innately provide information on the level of evidence and the strength of what the panel of experts agrees *** are several consensus group methods by which these statements can be *** is a systematic process to create and measure consensus,which is particularly well suited where input is required from a large number of geographically dispersed experts.

关键词： Cirrhosis hepatorenal albumin point-of-care ultrasound(POCUS) ultrasound