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Sidewall influence of varying free stream Mach number in ramp induced shock wave boundary layer interactions

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Theoretical & Applied Mechanics Letters 2024年第4期14卷 298-305页

作者： Raja Mangalagiri satya p.Jammy Department of Mechanical Engineering SRM University APAndhra Pradesh 522502India

This study investigates the three-dimensional(3D)effects introduced by the end walls for an aspect ratio of1 in ramp-induced shock wave boundary layer *** simulations are performed using a symmetry boundary condition in the spanwise direction at free-stream Mach numbers in *** simulations are performed using an in-house compressible supersonic solver“Open SBLIFVM”.Two free stream Mach numbers 2.5,and3 are used in the current work,and the simulated results are compared with the aspect ratio 1 simulations by Mangalagiri and *** inflow is initialized with a similarity solution;its Reynolds number based on the boundary layer thickness is adjusted such that the Reynolds number at the start of the ramp is kept at 3×10^(5)for all *** the results,it is evident that the introduction of sidewalls resulted in a shorter centerline separation length when compared with the two-dimensional(2D)*** contradicts the results at Mach 2 by Mangalgiri and Jammy where the vortex observed at Mach 2 in the central separation region disappeared with increasing free-stream Mach ***,the topology of interaction shifted from owl-like separation of the second kind to the first kind when the freestream Mach number increased from2 to *** can be concluded that the interaction topology is crucial to the increase or decrease of the central separation length when compared to 2D simulations.

关键词： Shock boundary layer interaction Separation Compressible boundary layers GpGpU simulations RSWBLI

performance and Emission Characteristics of a CRDI Diesel Engine Fuelled by SiO_(2) Nanoparticle-Waste Fat Biodiesel Blends

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China petroleum processing & petrochemical Technology 2024年第1期26卷 56-66页

作者： babu Aurtherson p Dinesh babu Munuswamy Ravikumar Jayabal Yuvarajan Devarajan Department of Mechanical Engineering Mahat Amma Institute of Engineering and TechnologyPudukkottaiTamil NaduIndia Department of Mechanical Engineering Rajalakshmi Institute of TechnologyChennaiTamil NaduIndia Department of Thermal Engineering Saveetha School of EngineeringSaveetha Institute of Medical and Technical SciencesChennaiTamil NaduIndia

This study investigates the use of waste fat biodiesel(WFB)from the leather industry as a substitute for diesel ***,it examines the diesel engine performance of WFB,a blend of WFB and diesel(B50),and different blends of WFB and silicon dioxide(SiO_(2))nanoparticles(B50SiO_(2)40,B50SiO_(2)80,and B50SiO_(2)120μg/g).The results indicate that the B50SiO_(2)120 blend increases brake thermal efficiency by 10.03%compared to pure biodiesel but falls 1.93%short of neat ***,the B50SiO_(2)120 mixture reduces smoke,hydrocarbon,and carbon monoxide emissions by 31.87%,34.14%,and 43.97%respectively,compared to ***,the B50SiO_(2)120 blend shows a 4.91%increase in nitrogen oxide emissions compared to diesel.

关键词： waste fat transesterification biodiesel silicon dioxide emission

Effect of Heat Sink and Cooling Mediums on Ferrite Austenite Ratio and Distortion in Laser Welding of Duplex Stainless Steel 2205

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Chinese Journal of Mechanical Engineering 2019年第3期32卷 209-217页

作者： p.Dinesh babu p.Gouthaman p.Marimuthu School of Mechanical Engineering SASTRA Deemed UniversityThanjavur 613401TamilnaduIndia Management Development Centre Ashok LeylandMookandapalliHosurTamilnaduIndia

In order to control the ferrite and austenite percentage in duplex stainless steel welding, many researchers try to change the laser welding parameters and cooling medium, but ignore to study the influence of heat sink effect on weld strength. In this work, the effect of aluminium heat sink and varying cooling medium on the laser welding of duplex stainless steel (DSS) 2205 is studied. The 2 mm thick DSS sheets welded with pulsed Nd: YAG laser welding machine by varying the cooling medium (air and oil) and an aluminium plate used as a heat sink. The welded specimens tested for tensile strength, micro-hardness, distortion, microstructure and radiography analysis. The faster cooling rate in the oil quenching process enhances the ferrite percentage compared with air-cooled samples. But the faster cooling rate in oil quenching leads to more distortion and using aluminium as a heat sink influenced positively the distortion to a small extent. The lower cooling rate in air quenching leads to a higher tensile strength of the welded specimen. The objective of this work is to analyse experimentally the effect of cooling medium and heat sink in the mechanical and metallurgical properties of laser welded duplex stainless steel.

关键词： Laser welding Duplex stainless steels Heatsink Cooling medium Distortion Tensile strength Radiography test

Effect of Gravity on Collective Excitations of a Quasi Two-Dimensional Bose Einstein Condensate in an Anharmonic Trap

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Communications in Theoretical physics 2011年第10期56卷 669-671页

作者： p.D.Anoop Ramesh babu Thayyullathil Department of physics Cochin University of Science and TechnologyCochin 682022KeralaIndia

Abstract Using variational method, the wave function of a quasi two-dimensional Bose-Einstein Condensate in an anharmonic trap is analyzed and the influence of gravity on the eollective excitations is studied. It is f... 详细信息

关键词： Bose-Einstein condensation variational method collective excitations

Effects of variable permeability and radiation absorption on magnetohydrodynamic(MHD)mixed convective flow in a vertical wavy channel with traveling thermal waves

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propulsion and power Research 2015年第3期4卷 150-160页

作者： p.V.satya Narayana Fluid Dynamics Division SASVIT UniversityVellore-632014T.NIndia

An analysis has been carried out to study the effects of radiation absorption and firstorder chemical reaction on unsteady mixed convective flow of a viscous incompressible electrically conducting fluid through a porous medium of variable permeability between two long vertical non conducting wavy channels in the presence of heat *** unsteadiness in the flow is due to traveling thermal wave imposed on the *** governing equations are solved subject to the relevant boundary conditions with the assumption that the solution consists of a mean part and a perturbed *** zeroth-order,the first order and the total solution of the problem are numerically evaluated and displayed graphically for pertinent *** model finds applications in studying fixed-bed catalytic reactors and packed bed heat exchangers.

关键词： Magnetohydrodynamic(MHD) Chemical reaction Traveling thermal waves Radiation absorption Variable permeability

Characterization and Effect of Using Mahua Oil Biodiesel as Fuel in Compression Ignition Engine

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Journal of Thermal Science 2009年第4期18卷 382-384页

作者： N.Kapilan T.p.Ashok babu R.p.Reddy Department of Mechanical Engineering NITKSurathkal

There is an increasing interest in India, to search for suitable alternative fuels that are environment friendly. Thisled to the choice of Mahua Oil (MO) as one of the main alternative fuels to diesel. In this investigation, MahuaOil Biodiesel (MOB) and its blend with diesel were used as fuel in a single cylinder, direct injection and compressionignition engine. The MOB was prepared from MO by transesterification using methanol and potassiumhydroxide. The fuel properties of MOB are close to the diesel and confirm to the ASTM standards. From the enginetest analysis, it was observed that the MOB, B5 and B20 blend results in lower CO, HC and smoke emissionsas compared to diesel. But the B5 and B20 blends results in higher efficiency as compared to MOB. HenceMOB or blends of MOB and diesel (B5 or B20) can be used as a substitute for diesel in diesel engines used intransportation as well as in the agriculture sector.

关键词： Alternative fuel mahua oil biodiesel engine performance

photon condensation： A new paradigm for Bose-Einstein condensation

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Frontiers of physics 2016年第5期11卷 103-110页

作者： Renju Rajan p. Ramesh babu K. Senthilnathan Department of physics School of Advanced Sciences VIT University Vellore Tamil Nadu 632015 India

Bose-Einstein condensation is a state of matter known to be responsible for peculiar properties exhibited by superfluid Helium-4 and superconductors. Bose-Einstein condensate （BEC） in its pure form is realizable with alkali atoms under ultra-cold temperatures. In this paper, we review the experimental scheme that demonstrates the atomic Bose-Einstein condensate. We also elaborate on the theoretical framework for atomic Bose-Einstein condensation, which includes statistical mechan- ics and the Gross-pitaevskii equation. As an extension, we discuss Bose-Einstein condensation of photons realized in a fluorescent dye filled optical microcavity. We analyze this phenomenon based on the generalized planck＇s law in statistical mechanics. Further, a comparison is made between photon condensateand laser. We describe how photon condensate may be a possible alternative for lasers since it does not require an energy consuming population inversion process.

关键词： Bose-Einstein condensation photon condensation magneto-optical trap Gross-pitaevskii equation planck's radiation law

Experimental studies of water hammer in propellant feed system of reaction control system

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propulsion and power Research 2018年第1期7卷 52-59页

作者： Avanish Kumar p.satya prasad M.Raghavendra Rao Defence Research&Development Laboratory HyderabadTelangana 500058India

Water hammer pressure transient produces large dynamic forces which can damage the pipes and other assemblies in the feed line of a reaction control system(RCS).It has led to the failure of pressure transducers monitoring the manifold pressure in the feed line of ***,water hammer studies have been carried out to understand its effect in feed *** system has been simplified to develop a mathematical model and experiments have been carried out at extensive *** mathematical model was developed considering pipe of uniform c/s and moving liquid-gas *** experimental studies have been done using water as working medium instead of actual *** studies showed that rate of pressurization have a very critical role on the water hammer *** studies have been also carried out to study the effect of density,friction and initial liquid column length on water hammer amplitude.

关键词： Water hammer Reaction control system(RCS) propellant feed system Experimental study Testing

Characteristic Study of the Boundary Layer parameters over the Arabian Sea and the Bay of Bengal Using the QuikSCAT Dataset

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Advances in Atmospheric Sciences 2007年第4期24卷 631-643页

作者： V.HAMZA C.A.babu T.p.SABIN Department of Atmospheric Sciences Cochin University of Science and TechnologyCochin-682 016India

The marine atmospheric boundary layer （MABL） plays a vital role in the transport of momentum and heat from the surface of the ocean into the atmosphere. A detailed study on the MABL characteristics was carried out using high-resolution surface-wind data as measured by the QuikSCAT （Quick scatterometer） satellite. Spatial variations in the surface wind, frictional velocity, roughness parameter and drag coefficient for the different seasons were studied. The surface wind was strong during the southwest monsoon season due to the modulation induced by the Low Level Jetstream. The drag coefficient was larger during this season, due to the strong winds and was lower during the winter months. The spatial variations in the frictional velocity over the seas was small during the post-monsoon season （-0.2 m s^-1）. The maximum spatial variation in the frictional velocity was found over the south Arabian Sea （0.3 to 0.5 m s^-1） during the southwest monsoon period, followed by the pre-monsoon over the Bay of Bengal （0.1 to 0.25 m s^-1）. The mean wind-stress curl during the winter was positive over the equatorial region, with a maximum value of 1.5×10^-7 N m^-3, but on either side of the equatorial belt, a negative wind-stress curl dominated. The area average of the frictional velocity and drag coefficient over the Arabian Sea and Bay of Bengal were also studied. The values of frictional velocity shows a variability that is similar to the intraseasonal oscillation （ISO） and this was confirmed via wavelet analysis. In the case of the drag coefficient, the prominent oscillations were ISO and quasi-biweekly mode （QBM）. The interrelationship between the drag coefficient and the frictional velocity with wind speed in both the Arabian Sea and the Bay of Bengal was also studied.

关键词： boundary layer characteristics drag coefficient frictional velocity roughness length QuikSCAT wind