Conference Proceedings

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Author: search.filters.author.Janardhanan, Sheeja

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    Optimization of a hydro kinetic power generator using genetic algorithm
    (Spingerlink, 2021-12-27) Viswanath, Anjana; Chandran, Vidya; Janardhanan, Sheeja
    The paper discusses the optimization of a renewable energy harvester which converts kinetic energy of slow moving currents into electricity. The metaheuristic method of genetic algorithm is adopted to optimize the process parameters of the Hydro Vortex Power Generator (HVPG). The study is conducted in a three folded manner. The device was optimized for the range of Reynolds number 0.3 × 105 < Re < 2.5 × 105 based on equations derived analytically from vibration theory and then using an empirical equation derived from experimental data for two regimes of flow (250 < Re < 3.8 × 104 and 0.3 × 105 < Re < 2.5 × 105. Empirical optimization model is observed to predict the maximum amplitude of oscillation with in a realistic range with the theoretical model showing a three time over prediction. A comparison with experimental results suggests that the effect of added mass on the amplitude of oscillation is of enhanced damping and hence a more realistic prediction is obtained from empirical model optimization. The most significant result from this analysis is that the empirical model predicts maximum amplitude at lowest value of mass ratio (m*), whereas the theoretical model predicts it at the highest value.
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    Numerical study on domain independency for prediction of vortex shedding parameters of a circular cylinder
    (Spingerlink, 2022-04-29) Chandran, Vidya; Janardhanan, Sheeja; Sekar, M.
    The catastrophes of history make vortex-induced vibration an extensively studied area. The response predictions of offshore and sub-sea structures have gained importance off-late ever since these have been widely used by the petroleum industry. Most of the studies have confined to the comprehension of wake characteristics and the estimation of hydrodynamic loading and shedding parameters of stationary cylinders. Computational fluid dynamics has evolved as one of the effective tools in prediction of response characteristics under vortex shedding and many researchers have studied various aspects of computations that are crucial with reasonable degree of accuracy. This paper addresses the effect of the geometrical shape of fluid domain that encompasses a marine riser during simulations. Four different shapes are analyzed using Reynolds Averaged Navier–Stokes Equation-based commercial solver, ANSYS®. All four domains have the same number of elements, mesh density, and flow Reynolds number (Re). Hydrodynamic force coefficients and frequency of shedding in each case were estimated and compared with previously published numerical and experimental results. It is observed that circular domain is the most efficient in predicting both loading and shedding characteristics with less than 10% deviation as against the theoretical results. Elliptical and square domains failed to capture the vortex shedding phenomenon. The study reveals a significant characteristic of numerical simulations on the modeling and meshing of both near-wall and wake regions.
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    Estimation of stability derivatives due to translational motion of various LTA vehicles using CFD
    (Spingerlink, 2022-11-29) Sasidharan, Anoop; Velamati, Ratna Kishore; Janardhanan, Sheeja; Oruganti, Venkata Ramana Murthy; Mohammad, Akram
    In this paper, the aerodynamic model parameters (stability derivatives) of the aerostat are investigated based on a CFD-based approach. The stability derivatives due to the translational motion of the aerostat are considered for the analysis in this paper. The extraction of the stability derivatives involves the simulation of the oscillations of the aerostat along the vertical direction (heave motion) and axial direction (surge motion). A forced sinusoidal oscillation is used for the simulation of the aerostat, and one stable period of oscillation is taken for the derivatives extraction. Four different aerostats are considered for the current study with four different angles of attack. Zhiyuan aerostat, HAA aerostat, NPL aerostat and GNVR aerostat are the aerostats considered for this study. The stability derivative results obtained for the four aerostats are analysed and compared with respect to their geometrical features. The dynamic stability derivatives of the Zhiyuan aerostat suggest its superiority among the four aerostats considered.
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    Aerodynamic analysis of deployable wing arrangement for space shuttle
    (Spingerlink, 2022-11-19) Chandran, Vidya; Rajendran, Poornima; Gopakumar, Shabu; Arun Kumar, K. S.; Nikhilraj, C. A.; Janardhanan, Sheeja
    The study space for morphing wings is astonishingly wide and provides ample scope for enhancements up against fixed wings. Morphing-wing research has accumulated considerable recognition in the aerospace community over the last decade, and a folding wing is a promising approach that can improve aircraft proficiency over multiple varieties of missions which conclusively enhance the capability of the space shuttle. In this paper, the conventional shape of the wings is being refashioned to serve the requirements for maintaining the flight and also for navigation. The idea was sparked by the traditional Japanese fan and has a hinged mechanism similar to that of the fan. This work introduces a novel concept for retractable dynamic wings on a space shuttle. Modeling of the spacecraft with modified wings is done in SOLIDWORKS. The aerodynamic analysis is performed using the computational fluid dynamics (CFD) method with ANSYS FLUENT® (2020 R1) as the solver. The aerodynamic force coefficients are estimated for five different specific deployment phases, viz., zeroth (0°), one quarter (7.5°), half (15°), three-quarter (22.5°), and full (30°) phases. The result reveals that the coefficient of drag drops and the coefficient of lift rises from the primary phase to the final phase providing promising inputs into the idea of retractable wings.