Mandal G.,National Physical Laboratory India |
Gopan C.K.,Fluid Control Research Institute
21st Conference on Measurement of Force, Mass and Torque Together with HARDMEKO 2010 and 2nd Meeting on Vibration Measurement, IMEKO TC3, TC5 and TC22 Conferences | Year: 2010
The National Physical Laboratory, India (NPLI) is the custodian of National Prototype of the Kilogram (NPK) No. 57, which was provided by the International Bureau of Weights and Measures (BIPM), Paris, France in 1958 after its first calibration in 1955. The NPK has been recalibrated three times (1985, 1992 & 2002) so far at the BIPM. All NPL working standards (Multiples & sub-multiples of 1 kg) range from 1 mg to 20 kg are re-established using new value of NPK through four Transfer Standards of 1 kg (two made of Stainless steel and two made of Nickel-Chromium alloy) according to defined periodicity. The calibration of multiples of 1 kg is carried out using a fully automatic mass comparator with maximum capacity of 64 kg and resolution of 0,1 mg. Using this mass comparator, we have improved our calibration and measurement capabilities (CMCs) from 0,6 mg to 0,2 mg (k=2) in 2 kg, from 1,5 mg to 0,3 mg (k=2) in 5 kg, from 3 mg to 0,5 mg (k=2) in 10 kg and from 6 mg to 1,0 mg (k=2) in 20 kg. The details of measurement technique and results of multiples of 1 kg are discussed in this paper.
Sreekala S.K.,Fluid Control Research Institute |
Thirumalini S.,Amrita University
International Journal of Multiphysics | Year: 2016
Noise pollution will soon become the third greatest menace to the human environment after air and water pollution. Since noise is a by-product of energy conversion, there will be increasing noise as the demand for energy for transportation, power, food, and chemicals increases. In the field of control equipment, noise produced by valves has become a focal point of attention. In this paper aerodynamic noise evaluation of a globe valve was carried out using a three dimensional Computational Fluid Dynamic technique(CFD). The results obtained from numerical analysis are compared with the experimental measurements and are found to be in good agreement. Reduction in sound pressure level was achieved by doubling the number of flow passages in the cage at full open condition and at the same operating conditions. Hence sound attenuation is established by changing the cage configuration with no change in total area of flow passage in the cage.
Suresh M.,Indian Institute of Technology Madras |
Vasa N.J.,Indian Institute of Technology Madras |
Agarwal V.,Indian Institute of Technology Bombay |
Chandapillai J.,Fluid Control Research Institute
Sensors and Actuators, B: Chemical | Year: 2014
A high-field Asymmetric Waveform Ion Mobility Spectrometry (FA-IMS) with ultra-violet (UV) photo-ionization source is proposed and demonstrated for measurement of trace amounts of volatile organic compound (VOC) gases. Experimental studies performed with the sensor using a high frequency asymmetrical waveform differential field for detection of acetone, hexane and acetone-hexane mixture in trace concentrations are discussed. The detection limit as estimated for a signal-to-noise ratio of 3 is of the order of 100 ppb for acetone and hexane. Experimental studies clearly show that selective sensing of a gas in a mixture of gases is also possible by appropriate value for the compensation voltage. Numerical Simulation is also performed using two-dimensional fluid-flow equations to estimate the motion of ions in an electric field. The study also demonstrated influence of parameters such as flow velocity, duty-ratio, on compensation voltage for detection of trace VOC gases with asymmetrical high-frequency electric field. Results based on theoretical study are in agreement with the experimental studies. © 2014 Elsevier B.V.
Velusamy K.,Indira Gandhi Center for Atomic Research |
Chellapandi P.,Indira Gandhi Center for Atomic Research |
Jebaraj C.,Anna University |
Mascomani R.,Fluid Control Research Institute
Nuclear Engineering and Design | Year: 2013
Computational fluid dynamics (CFD) investigations of flow and pressure distributions in the primary sodium header of fast reactor have been carried out. The focus of the study is to quantify the magnitude of swirl superimposed on main flow and assess its influence on pressure loss in the header and flow mal-distribution among the primary pipes. From compact layout considerations, a spherical shape has been chosen for the header. The static pressure loss coefficient for the basic 'header-primary pipe' assembly without any internals is determined to be 7.2. With suitable internal baffles and a central cone this value is reduced to 1.22. The loss coefficients predicted by CFD studies have been validated by conducting experiments on 1:3 scale air models. Following this, an integrated CFD study of header coupled with sodium pump including impeller and diffuser has been carried out. It is seen that the diffuser induces a strong swirl in the fluid entering the header. Due to this swirl, the total pressure loss coefficient in the header-pipe assembly increases by a factor of two, when compared to that without the swirl. The swirl also leads to flow mal-distribution among the two primary pipes to the extent of ±9% from the mean value. This flow mal-distribution is an important input for safety analysis of the reactor for the event of 'one primary pipe rupture'. © 2012 Elsevier B.V.
Chandapillai J.,Fluid Control Research Institute |
Sudheer K.P.,Indian Institute of Technology Madras |
Saseendran S.,Fluid Control Research Institute
Water Resources Management | Year: 2012
Water shortage is experienced in different parts of the world in different magnitude. In certain countries, water deficit is a regular phenomenon and in some other countries it happens for a short duration, due to failure of any component in the system. Shortage of water at source can be best tackled by distributing the available water equally among the consumers. This paper deals with the design of water distribution network capable of equitable supply during shortage in addition to the satisfactory performance under non-deficit condition. Performance of a typical water distribution network, with shortage of water at source is illustrated in detail. Head dependent outflow analysis with extended period simulation, is used to determine the actual supply from each node to consumers. Relationship between duration of supply and volume available at source as well as supply from each node are established for understanding the behaviour of network under low supply situation. A term "inequity" which is the maximum difference in supply demand ratio among different consumers is presented. This is based on the actual performance of the network instead of surrogate measures, generally used for reliability. It is illustrated that the maximum "inequity" in supply in a network during the entire duration of supply can be estimated with single analysis. Design of a water distribution network, duly considering equity in addition to the cost minimization and minimum head requirement is presented. Genetic Algorithm is used for solving this multi objective problem. The solution technique is illustrated using two benchmark problems, namely two loop network and Hanoi network. Results show that considerable improvement in equitable supply can be achieved with additional investment on pipes above the least cost solution. Hence it is better to design networks duly considering deficit condition for better reliability. It is also illustrated that it will be difficult to improve equity beyond a limit for a given network, through selection of different pipe diameters. © 2011 Springer Science+Business Media B.V.