检索结果-南通市图书馆

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

Computational Study of performance Characteristics for Truncated Conical Aerospike Nozzles

在线全文

学校读者我要写书评

暂无评论

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.

Influence of quenching medium on the dendrite morphology,hardness,and tribological behaviour of cast Cu-Ni-Sn spinodal alloy for defence application

在线全文

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2023年第12期30卷 83-100页

作者： Bipin Sankar Karthik V Shankar Vamu Sunil Hemanth Kashyap S Nikhil nair Adarsh A.nair Abhinav p M Department of Mechanical Engineering Amrita Vishwa VidyapeethamAmritapuriIndia

Cu-Ni-Sn spinodal alloys(Spinodal bronze)are potential materials with robust applications in components associated with defence applications like bearings,propellers,bushes,and shafts of heavily loaded aircraft,off-road vehicles,and *** paper presents a comparative study using water,Brine solution,and SAE 40 oil as the quenching media in regular bronze(Cu-6Sn)and spinodal bronze(Cu-9Ni-6Sn)*** analysis was conducted by optical microscopy,transmission electron microscopy(TEM),and X-ray diffraction technique(XRD)on bronze and spinodal bronze samples immersed in the three different quenching media to understand the grain size and hardness values *** analysis was performed to analyze the effect of quenching media on the wear aspects of bronze and spinodal bronze *** hardness value of the brine-aged spinodal bronze samples was as high as 320 Hv,and the grain size was very low in the range of 60μm.A quantitative comparison between brine-aged regular bronze and brine-aged spinodal bronze showed that the hardness(Hv)was almost 80%higher for brine-aged spinodal ***,the grain size was approximately 30%finer for spinodal bronze when compared with regular *** the load was increased in spinodal bronze samples,there was an initial dip in wear rate followed by a marginal *** was a steady increase in friction coefficient with a rise in load for brine-aged regular bronze and spinodal bronze *** results indicate that brine solution is the most effective quenching medium for cast Cu-Ni-Sn spinodal alloys.

关键词： Quenching Water Brine SAE 40 oil Grain size Hardness Wear rate Spinodal decomposition CuSn Spinodal alloy CuNiSn

Influence of Unbalance on Classification Accuracy of Tyre pressure Monitoring System Using Vibration Signals

在线全文

学校读者我要写书评

暂无评论

Structural Durability & Health Monitoring 2021年第3期15卷 261-279页

作者： p.S.Anoop pranav nair V.Sugumaran School of Mechanical Engineering Vellore Institute of TechnologyChennai CampusChennai600127India School of Electrical Engineering Vellore Institute of TechnologyChennai CampusChennai600127India

Tyre pressure Monitoring Systems(TpMS)are installed in automobiles to monitor the pressure of the *** pressure is an important parameter for the comfort of the travelers and the safety of the *** methods have been researched and reported for *** them,vibration-based indirect TpMS using machine learning techniques are the recent *** literature reported the results for a perfectly balanced ***,if there is a small unbalance,which is very common in automobile wheels,‘What will be the effect on the classification accuracy?’is the question on *** paper attempts to study the effect of unbalance of the wheel on the classification accuracy of an indirect TpMS *** tyres filled with air are considered with different pressure values to represent puncture,normal,under pressure and overpressure *** vibration signals of each condition were acquired and processed using machine learning *** procedure is carried out with perfectly balanced wheels and known unbalanced *** results are compared and presented.

关键词： Tyre pressure monitoring system wheel unbalance random committee classifier machine learning

Collapse of charge ordering in Bi_(0.5)Sr_(0.5)MnO_3 by cation disorder: a magnetic and structural investigation

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Rare Earths 2008年第2期26卷 237-240页

作者： S. Savitha pillai Rajasekhar Madugundo Santhosh. p. Nagappan nair Low Temperature physics Laboratory Department of Physics Indian Institute of Technology Madras Chennai -600036 Defence Metallurgical Research Labora- tory

The structure, transport, and magnetic properties of ***0.5MnO3 （LBSMO）（x=0.1 and 0.4） were studied through X-ray diffraction, magnetization, and electron spin resonance （ESR） measurements. The structural analysis showed that the LBSMO crystallized in an orthorhombic perovskite structure with pbnm space group for x=-0.1 and Imma space group for x=0.4 and the highly polarizable 6s^2 lone pair of Bi^3＋ was the ttming factor for the structural variations. Magnetic studies revealed that the replacement of Bi ions by La ions resulted in the collapse high temperature charge ordering state of BSMO and it order Ferro Magnetically （FM） with Tc around 355 and 330 K for x=0.1 and 0.4, respectively. Both ESR, temperature and field dependant magnetization suggested that there was a coexistence of FM and the paramagnetic phases well below Tc and the FM and CO-AFM phases below 250 K of LBSMO.

关键词： charge ordering (CO) colossal magneto resistance (CMR) rare earths

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

在线全文

学校读者我要写书评

暂无评论

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

Analytical modeling of AlInSb/InSb MOS gate HEMT structure with improved performance

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Modeling, Simulation, and Scientific Computing 2016年第3期7卷 386-394页

作者： T.D.Subash T.Gnanasekaran p.Deepthi nair Department of ECE K.N.S.K.College of Engineering Nagercoil TamilnaduIndia Department of IT R.M.K.College of Engineering and Technology Chennai TamilnaduIndia Department of ECE Annai Vailankanni College of Engineering Kanyakumari TamilnaduIndia

The performance of AlInSb/InSb heterostructure with various parameters is considered with T-Cad *** the heterojunctions are having more advantageous properties that is a real support for so many application such as solar cells,semiconductor cells and *** properties of semiconductors are discussed here with various parameters that are depending up on the performance of accurate device[pardeshi H.,pati S.K.,Raj G.,Mohankumar N.,Sarkar C.K.,***.33(12):124001-1–124001-7,2012].The maximum drain current density is achieved with improving the density of two-dimensional electron gas(2DEG)and with high *** electron mobility transistor(HEMT)structure is used with the different combinations of layers which have different *** such as electron mobility,bandgap,dielectric constant,etc.,are considered differently for each layer[Zhang A.,Zhang L.,Tang Z.,IEEE *** Devices 61(3):755–761,2014].The high electron mobility electrons are now widely used in so many *** proposed work of AlInSb/InSb heterostructure implements the same process which will be a promise for future research works.

关键词： Heterostructure 2DEG HEMT bandgap

Influence of cryogenic treatment on the wear characteristics of 100Cr6 bearing steel

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2014年第1期21卷 46-51页

作者： R.Sri Siva D.Mohan Lal p.Kesavan nair M.Arockia Jaswin Department of Mechanical Engineering College of Engineering GuindyAnna University Department of Metallurgical and Material Engineering Indian Institute of Technology Madras Department of Mechanical Engineering Aksheyaa College of Engineering

A series of reciprocating wear tests were performed on the deep cryogenically treated and conventionally heat-treated samples of 100Cr6 bearing steel to study the wear resistance. The worn surfaces as well as the wear debris were analyzed by scanning electron microscopy. The improvement in wear resistance of the deep cryogenically treated samples ranges from 49% to 52%. This significant improvement in wear resistance can be attributed to finer carbide precipitation in the tempered martensitie matrix and the transformation of retained aus- tenite into martensite. X-ray diffraction analysis shows that the volume fraction of retained austenite in the conventionally heat-treated samples is 14% and that of the deep cryogenically treated samples is only 3%.

关键词： bearing steel cryogenic treatment wear resistance carbides martensite

Identification of slot discharges in rotating machine insulation system using variable frequency pD measurement

在线全文

学校读者我要写书评

暂无评论

High Voltage 2018年第3期3卷 179-186页

作者： Ramesh p.nair Sumangala B.Vishwanath Nageshwar B.Rao Cables and Diagnostics Division Central Power Research InstituteBengaluruIndia Dr.Ambedkar Institute of Technology BengaluruIndia

Slot discharge studies are very important from the insulation diagnosis *** in practice,testing of rotating machines with power frequency requires sources which are quite bulky and *** if the diagnosis is carried out at lower frequencies(portant to know whether the study at low frequencies can be considered equivalent to study at power ***,in this study,a slot discharge phenomenon occurring in a rotating machine insulation system was investigated experimentally at different frequencies(50,10,1 and 0.1 Hz).Slot discharges are known to have a distinct phase resolved partial discharge pattern for power frequency(50/60 Hz)*** distinct patterns are useful in identifying the presence of slot discharge activity in rotating *** discharges were created on a 6.6 kV mica-epoxy stator coil and the slot discharge characteristics measured at different frequencies are *** discharge measurements were repeated by varying the air gap between the insulation surface and grounded steel *** changes in slot discharge characteristics due to the increase in air gap were found similar at all *** comparison suggests that the identification of slot discharge is also possible from the partial discharge(pD)measurement at low frequencies.

关键词： steel rotating insulation

photoanode Activity of ZnO Nanotube Based Dye-Sensitized Solar Cells

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2011年第11期27卷 961-966页

作者： R. Ranjusha p. Lekha K.R.V. Subramanian V. nair Shantikumar A. Balakrishnan Nano Solar Division Amrita Center for Nanosciences

Vertical ZnO nanotube （ZNT） arrays were synthesized onto an indium doped tin oxide （ITO） glass substrate by a simple electrochemical deposition technique followed by a selective etching process. Scanning electron microscopy （SEM） showed formation of well-faceted hexagonal ZNT arrays spreading uniformly over a large area. X-ray diffraction （XRD） of ZNT layer showed substantially higher intensity for the （0002） diffraction peak, indicating that the ZnO crystallites were well aligned with their c-axis. profilometer measurements of the ZNT layer showed an average thickness of -7 μm. Diameter size distribution （DSD） analysis showed that ZNTs exhibited a narrow diameter size distribution in the range of 65-120 nm and centered at -75 nm. The photoluminescence （pL） spectrum measurement showed violet and blue luminescence peaks that were centered at 410 and 480 nm, respectively, indicating the presence of internal defects. Ultra-violet （UV） spectroscopy showed major absorbance peak at ,-348 nm, exhibiting an increase in energy gap value of 3.4 eV. By employing the formed ZNTs as the photo-anode for a dye-sensitized solar cell （DSSC）, a full-sun conversion efficiency of 1.01% was achieved with a fill factor of 54%. Quantum efficiency studies showed the maximum of incident photon-to-electron conversion efficiency in a visible region located at 590-550 nm range.

关键词： ZnO nanotubes Indium doped tin oxide (ITO) glass photoluminescence spectra Electrochemical deposition Quantum efficiency