Faculty Publications

Now showing 1 - 2 of 2

Computational analysis of unsteady flow in turbine part of turbocharger
(Springer Heidelberg, 2017) Rao, H.K.S.; Raviteja, S.; Kumar, G.N.
Turbocharging technique is widely employed in internal combustion engines to improve the performance and to reduce the exhaust emissions. Flow analysis through the turbocharger has been a guiding method to optimize the turbocharger design. Usually, the turbocharger turbine is analyzed at steady states. But in practical scenario the turbine operates with unsteady flow due to the reciprocating motion of exhaust port and creates unsteady environment in the turbine. In order to increase turbine efficiencies and effective engine turbocharger matching, proper understanding of unsteady flow physics within the turbine is essential. Currently the turbine and compressors maps are obtained by using 1D code which includes extrapolation techniques. These methods neglect heat transfer and windage effects, hence resulting in lower aerodynamic efficiencies. Three dimensional analysis could lead to a better estimation of the flow field, helping the designer to build a high efficiency turbocharger. The present article concentrates on investigating unsteady flow field in the turbine part of a turbocharger. The necessary unsteady conditions at turbine inlet were obtained using commercially available one dimensional engine simulation software AVL Boost. A turbocharged twin cylinder CRDI diesel engine test rig was modelled within the workspace. The exhaust mass flow rate, pressure and temperature were recorded as a function of crank angle. These results were used as the boundary condition for the 3D analysis of the turbine. ANSYS CFX tools were used to solve the unsteady case. The turbine geometry was generated using ANSYS bladegen. The model selected for analysis is k-? turbulence Model. The pulsating performance, effect of secondary flows and entropy generation are discussed in the paper. © Springer India 2017.
Performance analysis of a semi-active suspension system using coupled CFD-FEA based non-parametric modeling of low capacity shear mode monotube MR damper
(SAGE Publications Ltd, 2019) Gurubasavaraju, G.; Kumar, H.; Mahalingam, A.
In this work, an approach for formulation of a non-parametric-based polynomial representative model of magnetorheological damper through coupled computational fluid dynamics and finite element analysis is presented. Using this, the performance of a quarter car suspension subjected to random road excitation is estimated. Initially, prepared MR fluid is characterized to obtain a relationship between the field-dependent shear stress and magnetic flux density. The amount of magnetic flux induced in the shear gap of magnetorheological damper is computed using finite element analysis. The computed magnetic field is used in the computational fluid dynamic analysis to calculate the maximum force induced under specified frequency, displacement and applied current using ANSYS CFX software. Experiments have been conducted to verify the credibility of the results obtained from computational analysis, and a comparative study has been made. From the comparison, it was found that a good agreement exists between experimental and computed results. Furthermore, the influence of fluid flow gap length and frequency on the induced force of the damper is investigated using the computational methods (finite element analysis and computational fluid dynamic) for various values. This proposed approach would serve in the preliminary design for estimation of magnetorheological damper dynamic performance in semi-active suspensions computationally prior to experimental analysis. © IMechE 2018.

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