로켓노즐에서 발생하는 횡력변동에 관한 연구

Suryakant Nagdewe,이종성(Jongsung Lee),김희동(Heuydong Kim) 한국추진공학회 2009 한국추진공학회 학술대회논문집 Vol.2009 No.5

Investigation of the lateral force fluctuations in an axisymmetric overexpanded compressed truncated perfect (CTP) nozzle for the shutdown transient is presented. These nozzles experience side-loads during start-up and shut-down operations, because of the flow separation at nozzle walls. Two types of flow separations such as free shock separation (FSS) and restricted shock separation (RSS) shock structure occur. A two-dimensional unsteady numerical simulation has been carried out over an axisymmetric CTP nozzle to simulate the lateral force fluctuations in nozzle during shutdown process. Reynolds Averaged Navier-Stokes equations are numerically solved using a fully implicit finite volume scheme. Governing equations are solved by coupled implicit scheme. Two equation k-ω SST turbulence model is selected. Unsteady pressure is measured at four locations along the nozzle wall. Present pressure variation compared well with the experimental data. During shutdown transient, separation pattern varies from FSS to RSS and finally returns to FSS. Several pressure peaks are observed during the RSS separation pattern. These pressure peaks generate lateral force or side loads in rocket nozzle.

A Computational Study on the Unsteady Lateral Loads in a Rocket Nozzle

Suryakant Nagdewe,Heuy Dong Kim 한국추진공학회 2008 한국추진공학회 학술대회논문집 Vol.2008 No.5

Highly over-expanded nozzle of the rocket engines will be excited by non-axial forces due to flow separation at sea level operations. Since rocket engines are designed to produce axial thrust to power the vehicle, non-axial static and/or dynamic forces are not desirable. Several engine failures were attributed to the side loads. Present work investigate the unsteady flow in an over-expanded rocket nozzle in order to estimate side load during a shutdown/starting. Numerical computations has been carried out with density based solver on multi-block structured grid. Present solver is explicit in time and unsteady time step is calculated using dual time step approach. AUSMDV is considered as a numerical scheme for the flux calculations. One equation Spalart-Allmaras turbulence model is selected. Results presented here is for two nozzle pressure ratio i.e. 100 and 20. At 100 NPR, restricted shock separation (RSS) pattern is observed while, 20 NPR shows free shock separation (FSS) pattern. Side load is observed during the transition of separation pattern at different NPR.

A Computational Study on the Unsteady Lateral Loads in a Rocket Nozzle

Suryakant Nagdewe,Heuydong Kim 한국추진공학회 2008 한국추진공학회 학술대회논문집 Vol.2008 No.11

A numerical study of the unsteady flow in an over-expanded thrust optimized contour and compressed truncated perfect rocket nozzle is carried out in present paper. These rocket nozzles are subject to flow separation in transient phase at engine start-up and/or engine shut-down. The separation flow structures at different pressure ratios are observed. The start-up process exhibits two different shock structures such as FSS (Free Shock Separation) and RSS (Restricted Shock Separation). For a range of pressure ratios, hysteresis phenomenon occurs between these two separation patterns. A three-dimension compressible Navier-Stokes solver is used for the present study. One equation Spalart-Allmaras turbulence model is selected. The computed nozzle wall pressures show a good agreement with the experimental measurements. Present results have shown that present code can be used for the analysis of the transient flows in nozzle.

극초음속 유동의 열전달 예측에 관한 수치해석적 연구

Suryakant Nagdewe,김희동(H. D. Kim) 한국추진공학회 2007 한국추진공학회 학술대회논문집 Vol.2007 No.11

Functional and Radiological Outcomes of Anterior Decompression and Posterior Stabilization via Posterior Transpedicular Approach in Thoracic and Thoracolumbar Pott's Disease: A Retrospective Study

Suryakant Singh,Hitesh Dawar,Kalidutta Das,Bibhudendu Mohapatra,Somya Prasad 대한척추외과학회 2017 Asian Spine Journal Vol.11 No.4

Study Design: This is a retrospective study. Purpose: To determine the efficacy and safety of a posterior transpedicular approach with regard to functional and radiological outcomes in people with thoracic and thoracolumbar spinal tuberculosis. Overview of Literature: Spinal tuberculosis can cause serious morbidity, including permanent neurological deficits and severe deformities. Medical treatment or a combination of medical and surgical strategies can control the disease in most patients, thereby decreasing morbidity incidence. A debate always existed regarding whether to achieve both decompression and stabilization via a combined anterior and posterior approach or a single posterior approach exists. Methods: The study was conducted at the Indian Spinal injuries Centre and included all patients with thoracic and thoracolumbar Pott's disease who were operated via a Posterior transpedicular approach. Data regarding 60 patients were analyzed with respect to the average operation time, preoperative and postoperative, 6 months and final follow-up American Spinal Injury Association (ASIA) grading, bony fusion, implant loosening, implant failure, preoperative, postoperative, 6 months and final follow-up kyphotic angles, a loss of kyphotic correction, Oswestry disability index (ODI) score, and visual analog scale (VAS) score. Data were analyzed using either a paired t -test or a Wilcoxon Signed Rank test. Results: The mean operation time was 260±30 minutes. Fifty-five patients presented with evidence of successful bony fusion within a mean period of 6±1.5 months. Preoperative dorsal and lumbar angles were significantly larger than postoperative angles, which were smaller than final follow-up angles. The mean kyphotic correction achieved was 12.11±14.8, with a mean decrease of 5.97 and 19.1 in VAS and ODI scores, respectively. Conclusions: Anterior decompression and posterior stabilization via a posterior transpedicular approach are safe and effective procedures, with less intraoperative surgical duration and significant improvements in clinical and functional status.

A Computational Study of Hypersonic Flows Using Energy Relaxation Method

Suryakant Nagdewe,H. D. Kim,G. R. Shevare 대한기계학회 2008 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.22 No.6

Reasonable analysis of hypersonic flows requires a thstrong shock waves or high pressure and temperature states in the flow field. The energy relaxation method (ERM) has been used to model such a non-equilibrium effect which is generally expressed as a hyperbolic system of equations with a stiff relaxation source term. Relaxation time that is multiplied with source terms is responsible for non-equilibrium in the system. In the present study, a numerical analysis has been carried out with varying values of relaxa-tion time for several hypersonic flows with AUSM (advection upstream splitting method) as a numerical scheme. Vi-laxation time reduces to zero, the solution marches toward equilibrium, while it shows non-equilibrium effects, as the relaxation time increases. The present computations predicted the experiment results of hypersonic flows with good accuracy. The work carried out suggests that the present energy relaxation method can be robust for analysis of hyper-sonic flows.

Nickel Nanoparticles: An Ecofriendly and Reusable Catalyst for the Synthesis of 3,4-Dihydropyrimidine-2(1H)-ones via Biginelli Reaction

Suryakant B. Sapka,Kiran F. Shelke,Bapurao B. Shingate,Murlidhar S. Shingare 대한화학회 2010 Bulletin of the Korean Chemical Society Vol.31 No.2

Nickel nanoparticles (Ni NPs) appeared to exhibit the catalytic activity in one-pot cyclocondensation reaction for the preparation of 3,4-dihydropyrimidine-2(1H)-ones via Biginelli reaction from aromatic/heteroaromatic/aliphatic aldehydes, urea/thiourea and ethyl acetoacetate under microwave irradiation has been described. The UV absorbance spectra showed metallic Ni characteristics and appreciate with the particle size determined by Transmission electron microscopy (TEM). After reaction course the Ni NPs can be re-covered and reused without any apparent loss of activity.

1-Butyl-3-Methyl Imidazolium Hydrogen Sulphate Promoted One-Pot Three-Component Synthesis of Amidoalkyl Naphthols

Suryakant B. Sapkal,Kiran F. Shelke,Balaji R. Madje,Bapurao B. Shingate,Murlidhar S. Shingare 대한화학회 2009 Bulletin of the Korean Chemical Society Vol.30 No.12

An efficient and easy method for one-pot three-component synthesis of amidoalkyl naphthols by the condensation of aromatic/heteroaromatic/aliphatic aldehydes, 2-naphthol and amides or urea under thermal condition at 60 °C in the presence of acidic ionic liquid 1-butyl-3-methylimidazolium hydrogen sulphate ([bmim]HSO4) has been described.

EFFECT OF RELAXATION TIME ON COMPUTATIONAL PREDICTION OF HYPERSONIC FLOWS

Suryakant Nagdewe,G. R. Shevare,H. D. Kim 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.10

Reasonable analysis of hypersonic flows requires a thermodynamic non-equilibrium model to properly simulate strong shock waves or high pressure and temperature states in the flow field. Energy Relaxation Method (ERM) has been used to model such a non-equilibrium effect which is generally expressed as a hyperbolic system of equations with a stiff relaxation source term. Relaxation time which is multiplied with source term is responsible for non-equilibrium in the system. In the present study, a numerical analysis has been carried out with varying values of relaxation time for several hypersonic flows with AUSM (Advection Upstream Splitting Method) as a numerical scheme. The results obtained showed that, as the relaxation time tends to zero, the solution marches toward equilibrium, while it shows nonequilibrium effects, as the relaxation time increases. The present computations predicted the experiment results of hypersonic flows with good accuracy.

Unsteady Simulation of the Separated Flow in Rocket Nozzle

Suryakant Nagdewe,이종성(Jong-Sung Lee),김희동(Heuy-Dong Kim) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5

Investigation of the separated flow in an axisymmetric overexpanded compressed truncated perfect (CTP) nozzle for the shutdown transient is presented. These nozzles experience side-loads during start-up and shutdown operations, because of the flow separation at nozzle walls. Two types of flow separations such as free shock separation (FSS) and restricted shock separation (RSS) shock structure occur. A two-dimensional unsteady numerical simulation has been carried out over an axisymmetric CTP nozzle to simulate the flow separation in nozzle during shutdown process. Reynolds Averaged Navier-Stokes equations are numerically solved using a fully implicit finite volume scheme. Governing equations are solved by coupled implicit scheme. Two equation k-ω SST turbulence model is selected. Unsteady pressure is measured at four locations along the nozzle wall. Present pressure variation compared well with the experimental data. During shutdown transient, separation pattern varies from FSS to RSS and finally returns to FSS. Pressure peaks are observed during the RSS separation pattern, at the reattachment point.