Showing papers by "S.V. Prabhu published in 2017"
TL;DR: In this article, the effect of overlap ratio and aspect ratio on the performance of a Savonius turbine for hydrodynamic application is studied. And the influence of endplates is studied to establish the significance of their presence on rotor performance.
Abstract: Summary
A strong contender for the utilization of the hydropower sources is Savonius turbine because of its good starting characteristics and simplicity in fabrication. The aim of the present work is to study the effect of overlap ratio and aspect ratio on the performance of a Savonius turbine for hydrodynamic application. The findings would be useful to decide design parameters of a Savonius hydrokinetic turbine. This study is conducted in three open channels namely small laboratory channel with depth of water 270 mm, large laboratory channel with depth of water 480 mm and a real life irrigation canal with depth of water 900 mm. Influence of endplates is studied to establish the significance of their presence on rotor performance. Maximum coefficient of power is observed for an overlap ratio of around 0.11 for Savonius turbines with aspect ratio less than 0.6. For a given overlap ratio, the increasing trend of the coefficient of power is observed with the increase in the aspect ratio. However, for aspect ratios greater than 1.8, the coefficient of power becomes nearly stagnant. Copyright © 2016 John Wiley & Sons, Ltd.
91 citations
TL;DR: In this article, the experimental investigations are carried out to study the hydrodynamic performance of three bladed Darrieus turbine with NACA0015, NACA 0018 and NACA4415 blades for different solidities.
47 citations
TL;DR: In this article, the influence of curvature on local boiling heat transfer coefficient and two-phase pressure drop in helically coiled tubes with water as the working medium was investigated. But, very little information is available on the influence on flow boiling system.
27 citations
TL;DR: In this article, an experimental investigation is conducted to study the local heat transfer distribution on a flat surface normally impinged by a swirling air jet, where twisted tapes of twist ratios equal to 2, 3.2, 4.5 and 7.5 are inserted in a circular tube to generate swirling effect.
23 citations
TL;DR: In this paper, an attempt is made to thermally characterise the methane-air premixed impinging flame jets of a multi-port gas burner employing air jet cooling technique.
21 citations
TL;DR: The separation bubble is found to be both bi-stable and symmetric for lower slit widths and the interaction of the separation bubble with the outer vortices is seen to affect the strength of the primary/outer vortex.
Abstract: Visualization experiments for flow around a cylinder with parallel slit placed inside a circular pipe are carried out with water as the working medium. Two different color dyes are employed to visualize the complex vortex formation mechanism behind the bluff bodies. The objective of this study is to explore the potential of cylinder with parallel slit as an improved vortex generator for various practical applications. Wake parameters, such as Strouhal Number, wake width, and vortex formation length, are calculated from the recorded images. Three different slit widths with non-dimensional separation ratio of 0.1, 0.2, and 0.4 are chosen to study the effect on the vortex formation mechanism and the corresponding wake parameters. The Reynolds number range covered in this study is Re
D
= 200–2300. Symmetric vortex formation from the outer surface is observed for lower slit widths, whereas for high slit widths, both in-phase and anti-phase shedding are observed. A separation bubble from each of the inner surface is formed which detaches from the bluff body to form a vortex at higher Reynolds numbers. The separation bubble is found to be both bi-stable and symmetric for lower slit widths. The interaction of the separation bubble with the outer vortices is seen to affect the strength of the primary/outer vortex. The slit width is seen to be an important parameter in determining the strength of the vortices. At higher slit width, the configuration behaves like a dual bluff body and strong crisscross vortex shedding is observed. Such novel kind of vortex formation mechanism can be utilized to improve the performance of numerous practical applications, such as flowmeters, heat exchangers, etc.
19 citations
TL;DR: In this paper, the authors investigated the behavior of wall heat transfer coefficient with randomized packing of uniformly sized spheres in packed beds and compared the results with different insert configurations and found that packed beds are effective.
16 citations
TL;DR: In this article, the authors measured the heat transfer and pressure drop in flow boiling with refrigerant R123 as the working medium and compared the available correlations with the increase of quality of quality.
16 citations
TL;DR: In this article, a refined methodology was developed to determine the spatial and temporal variation in the flame emissivity of pool fires, based on the calculation of flame transmissivity using an infrared camera with reference to electrically heated thin metal strips.
16 citations
TL;DR: In this paper, the authors presented a study on flow boiling crisis in helical coils at low pressure with water as working medium and collated the correlations of critical heat flux in Helical coils.
15 citations
TL;DR: In this paper, the influence of impinging underexpanded jets on local heat transfer is studied for nozzle pressure ratio (NPR) ranging from 2.4 to 5.1.
TL;DR: In this paper, an optimized contraction cone is introduced upstream to the vortex shedder to enhance the strength of the shed vortices and to suppress upstream flow distortion effects to improve the turndown ratio and flow distortion sensitivity.
TL;DR: In this article, a flow regime map is developed based on Reynolds number and Froude number to understand the parametric dependence responsible for fluid flow transitions in a partially filled rotating smooth pipe.
TL;DR: In this paper, the authors performed experiments with horizontal stainless steel calorimeters engulfed in pool fires and found that the heat transfer to the calorimeter was characterized by the heat flux.
Abstract: Characterization of heat transfer to calorimeters engulfed in pool fires is extremely important. To estimate the heat flux to the calorimeters, experiments are performed with horizontal stainless s...
TL;DR: In this paper, the influence of nozzle profile on heat transfer for underexpanded impinging jets was explored and it was observed that plate shock and pressure distribution over the plate have significant influence on the local heat transfer.
Abstract: Experimental study is carried out to explore the influence of nozzle profile on heat transfer for underexpanded impinging jets. Circular and elliptical orifices are used to generate underexpanded jets for underexpantion ratio ranging from 1.25 to 2.67. The supply pressure maintained in the present study ranges from 2.36 to 5.08 times the ambient pressure.
IR thermal imaging camera is used to measure surface temperature of thin foil at different nozzle to plate distances. Shadowgraph and pressure distribution are used to understand the flow structure and distribution of circular and elliptical nozzle. It is observed that plate shock and pressure distribution over the plate have significant influence on the local heat transfer. The performance of the circular orifice is far better at lower z/d. The axis switching is observed for an elliptical orifice. Correlation for local heat transfer predicts Nusselt number comparable within 15 % of experimental results.
TL;DR: In this paper, the effect of the mixture equivalence ratio on the heat transfer characteristics of impinging premixed methane-air flame jets of tube burners equipped with twisted tape inserts was investigated.
TL;DR: In this paper, the effect of water spray on the containment vessel pressure and the iodine scrubbing in a scaled down facility is investigated for the containment spray system of Indian pressurized heavy water reactors.
TL;DR: In this article, the authors explored the effect of upstream disturbances like a single 90°bend, double 90° bends (in plane and out of plane) on the performance of wafer cone flowmeters with same beta ratio ( β ) of 0.77 but different half cone angles ( α ) of 30° and 45°.