No abstract

Water is a prime source to all living beings, but for humans it is even more because of its usage to extract power. The idea behind the water turbine is derived from the parental species of wind turbine. The operating fluid properties like density, specific weight of water draw out differences between the two turbine kinds. The objective of the present work is to experimentally investigate the performance of a two bladed Savonius water turbine with an aspect ratio of 1.21 at low water velocity conditions viz. 0.3 m/s, 0.65 m/s and 0.9 m/s. The variation of torque and power with the considered water velocities has been studied. Also a performance study has been conducted with the aid of Computational Fluid Dynamics (CFD) using Ansys 14.0. A detailed study on the flow characteristics has been done that elaborates the factors like torque variation at different angles of rotation of the turbine, revealing high torque generation at 270° position. Also the effect of tip speed ratio (TSR) on performance (Cp) has been studied and found that maximum Cp of 0.343 is obtained for water velocity of 0.65 m/s with a TSR of 0.643. The results obtained through CFD are in agreement with the experimental results.

Purpose The heat transfer within a heat exchanger is highly influenced by geometry of the components especially those with hollow structures like tubes. This paper aims to intend toward the study of efficient and optimized heat transfer in the bends of superheater tubes, with different curvature ratio at constant Reynolds Number. Design/methodology/approach The effect of changing curvature ratio on enthalpy of the fluid passing through the superheater tubes for multi-pass system has been studied with the aid of computational fluid dynamics (CFD) using ANSYS 14.0. Initially a superheater tube with two pass system has been examined with different curvature ratios of 1.425, 1.56, 1.71, 1.85 and 1.99. An industry specified curvature ratio of 1.71 with two pass is investigated, and a comparative assessment has been carried out. This is intended toward obtaining an optimized radius of curvature of the bend for enhancement of heat transfer. Findings The results obtained from software simulation revealed that the curvature ratio of 1.85 provides maximum heat transfer to the fluid flowing through the tube with two pass. This result has been found to be consistent with higher number of passes as well. The effect of secondary flow in bends of curvature has also been illustrated in the present work. Research limitations/implications The study of heat transfer in thermodynamic systems is a never-ending process and has to be continued for the upliftment of power plant performances. This study has been conducted on steady flow behavior of the fluid which may be upgraded by carrying out the same in transient mode. The impact of different curvature ratios on some important parameters such as heat transfer coefficients will certainly upgrade the value of research. Originality/value This computational study provided comprehensive information on fluid flow behavior and its effect on heat transfer in bends of curvature of superheater tubes inside the boiler. It also provides information on optimized bend of curvature for efficient heat transfer process.

Wind turbine has gained a keen interest in the field of research but its low efficiency due to low working fluid density triggers the need for upgradation. However, this technology will get a boost if the factor of low density fluid is eradicated. This paper is intended towards the study of performance of the same design of Savonius wind turbine when operated in high density water. The density of water is approximately 1000 times more than air. In the present study, the performance of a two bladed Savonius wind turbine and a Savonius water turbine have been analyzed both experimentally and with the aid of Computational Fluid Dynamics (CFD) using Ansys 19.0, keeping the maximum power content (Pmax) of the fluid-stream constant. Coefficient of power (Cp) is one of the deciding factors for superiority of the turbines one over the other. For the study, three cases of power contents viz. 0.61 W, 6.2 W and 16.45 W have been considered. The results obtained suggest that the Savonius water turbine with the highest Cp value of 0.343 is dominant over Savonius wind turbine. The effects of tip speed ratio and Non-dimensional factor (γ) on performance of both the turbine kinds have also been studied.

<div class="section abstract"><div class="htmlview paragraph">Wheel Loaders are heavy equipment machines which are used in construction fields. The main structure of a wheel Loader has a front and a rear bogie, connected through articulating pin joints. The wheel loaders have two axles viz. front and rear axles carrying its Front and Rear bogies. The front axle carrying front frame is fixed and articulates clockwise and anticlockwise about rear frame. However, to reduce the spillage of material carried in bucket while travelling in uneven terrains, the rear axle is designed to oscillate along the roll direction of vehicle movement. The rear axle is connected to rear frame with bearing hub called axle oscillation hub having separate shaft arrangement with tapered roller bearings (TRB). When machine operates in uneven terrain, the oscillating rear axle hits the rear frame structure which induces an impact load on vehicle structure. Mass and speed of the vehicle play a critical role in loader stability and safety. Apart from these, the impact force caused due to the rear axle hitting the vehicle frame influences the durability of the structural components. This paper explains the study on predicting the relationship between machine operating mass, vehicle speed and axle hitting loads. The study also focuses on determining the steps for selecting both structural and stopper components based on prediction of impact loads induced on wheel loaders during rear axle oscillation.</div></div>