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Tank H.K.,Indian Space Research Organisation
Proceedings of the Indian National Science Academy | Year: 2012

This letter presents some new expressions for gravity without the big G and proposes their possible wave-theoreticalexplanation. This attempt leads to some insight that: (i) We need the proportionality-constant G because we measure masses and distances in our arbitrarily-chosen units of Kg. and Meters; whereas nature has her own units; if we measure masses in the units of 'total-mass of the universe' M0 and measure distances in the units of 'radius-of-the-universe' R0 then there is no need for any proportionality-constant. However, large uncertainties in the M0 and R0 limit the general application of this relation presently, (ii) The strength of gravity would be different if the total-mass of the universe were different. Then this conclusion is explained with the help of wave-theory, (iii) These new expressions lead to an insight that Planck'slength, Planck-mass and Planck's unit of time are geometric-mean-values of astrophysical quantities like: total-mass of the universe and the smallest-possible-mass hH 0/c2. (iv) There is a law followed by various systems-of-matter, like: the electron, the proton, the nucleus-of-atom, the globular-clusters, the spiral-galaxies, the galactic-clusters and the whole universe; that their ratio Mass/Radius2 remains constant. This law seems to be more fundamental man the fundamentalforces because it is obeyed irrespective of the case, whether the system is bound by strong-force, electric-force, or gravitational-force. Source


Muppa S.K.,National Atmospheric Research Laboratory | Anandan V.K.,Indian Space Research Organisation | Kesarkar K.A.,National Atmospheric Research Laboratory | Rao S.B.,Sri Venkateswara University | Reddy P.N.,Sri Venkateswara University
Atmospheric Research | Year: 2012

Characteristics of sea breeze circulations over a tropical Indian station have been studied, based on one year of observations, by Doppler Sound Detection and Ranging (SODAR) system at National Atmospheric Research Laboratory, Gadanki (13.5°N, 79.2°E), India. The effect of sea breeze circulations on the dynamics of low level flow patterns in atmospheric boundary layer over complex terrain in tropics is investigated. The study reveals that a sea-breeze front develops well along the eastern coastal plain of southern peninsular India and propagates over inland up to the distance about 80. km. It is found that the sea-breeze signal is well recognized during the months of February, March and April due to the presence of tropical easterlies. In these three months, SODAR observations indicate a late afternoon intensification of sea-breeze flow in the height range 0.2-0.6. km during 1400 and 2000 local time (LT). The decrease in temperature of 2°C and increase in relative humidity of 20% at surface level are observed on a sea breeze day as compared to a non-sea breeze day. Sea-breeze inland propagation is absent for the rest of the months due to the opposing meso-flow direction. ERA-Interim reanalysis U-velocity data over south-Asia grid also corroborates the deep-inland penetrations of sea breeze circulations over this site. © 2011 Elsevier B.V. Source


Shravan Kumar M.,National Atmospheric Research Laboratory | Anandan V.K.,Indian Space Research Organisation | Narayana Rao T.,National Atmospheric Research Laboratory | Narasimha Reddy P.,Sri Venkateswara University
Journal of Applied Meteorology and Climatology | Year: 2012

Two years of Doppler sodar measurements are used to study the time-height structure of the nocturnal boundary layer (NBL), its seasonal variation, and the characteristics of different types of NBL. A total of 220 clear-sky nights during which the inversion layer is clearly visible on a sodar echogram are examined. The NBL depth estimated with sodar data using a wind maxima criterion matches reasonably well with radiosonde-based NBL depth estimates. The NBL exhibits clear seasonal variation with greater depths during the monsoon season. Shallow NBLs are generally observed in winter. The evolution of NBL height shows two distinctly different patterns (called type 1 and type 2), particularly in the second half of the night. Type 1 NBL depth is nearly constant and the wind speed in this type is generally weak and steady throughout the night, while type 2 is characterized by moderate to strong winds with considerable variations in NBL height. The local circulation generated by the complex topography is clearly seen in type 1 throughout the night, whereas it is seen only in the first half of the night in type 2. Type 1NBLs seemto bemore prevalent overGadanki, India, with nearly 61% of total nights showing type 1 characteristics. Furthermore, type 1 NBL shows large seasonal variability with themajority of type 1 cases in winter. The type 2 cases aremostly observed inmonsoon (~60%) followed by summer (39%). The surface meteorological parameters during type 1 and type 2 cases are examined. Differences between type 1 and type 2 NBL patterns are discussed in relation to the surface forcing. © 2012 American Meteorological Society. Source


Shine S.R.,Indian Institute of Space Science and Technology | Sunil Kumar S.,Liquid Propulsion Systems Center | Suresh B.N.,Indian Space Research Organisation
Heat and Mass Transfer/Waerme- und Stoffuebertragung | Year: 2012

An experimental investigation is conducted to bring out the effects of coolant injector configuration on film cooling effectiveness, film cooled length and film uniformity associated with gaseous and liquid coolants. A series of measurements are performed using hot air as the core gas and gaseous nitrogen and water as the film coolants in a cylindrical test section simulating a thrust chamber. Straight and compound angle injection at two different configurations of 30°-10° and 45°-10° are investigated for the gaseous coolant. Tangential injection at 30° and compound angle injection at 30°-10° are examined for the liquid coolant. The analysis is based on measurements of the film-cooling effectiveness and film uniformity downstream of the injection location at different blowing ratios. Measured results showed that compound angle configuration leads to lower far-field effectiveness and shorter film length compared to tangential injection in the case of liquid film cooling. For similar injector configurations, effectiveness along the stream wise direction showed flat characteristics initially for the liquid coolant, while it was continuously dropping for the gaseous coolant. For liquid coolant, deviations in temperature around the circumference are very low near the injection point, but increases to higher values for regions away from the coolant injection locations. The study brings out the existance of an optimum gaseous film coolant injector configuration for which the effectiveness is maximum. © Springer-Verlag 2011. Source


Shine S.R.,Indian Institute of Space Science and Technology | Kumar S.S.,Liquid Propulsion Systems Center | Suresh B.N.,Indian Space Research Organisation
Energy Conversion and Management | Year: 2013

The flow field associated with cylindrical coolant jets inclined in tangential and azimuthal direction employed inside a circular pipe has been studied. Numerical results are compared with in-house experimental data for a row of circumferential film cooling holes with two distinct geometric configurations. Results provide insight into the film cooling performance and the heat transfer characteristics associated with this type of film-cooling jets. Secondary flow recirculation zones are found near the jet exit in the regimes close to the wall and the center. Its occurrence and length is found to be controlled by the geometric configuration of the coolant hole. This secondary flow structure and the jet impingement on the wall are found responsible for developing a maximum local Nusselt number downstream of coolant injection. Reverse heat transfer regimes are noted for conjugate walls with higher thermal conductivity. The spreading of the coolant around the circumference is mainly due to the asymmetric vorticity levels present at the jet exit plane. Higher tangential orientation of the coolant jet with the mainstream has resulted in lower injectant concentration near the test section wall and lower effectiveness throughout the test section. The results indicate that through the use of optimal coolant injector configurations, reduction in coolant requirement can be achieved. © 2013 Elsevier Ltd. All rights reserved. Source

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