• S Sarkar

      Articles written in Sadhana

    • Finite element analysis of misaligned rotors on oil-film bearings

      S Sarkar A Nandi S Neogy J K Dutt T K Kundra

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      The present work deals with a two-step nonlinear finite element analysis for misaligned multi-disk rotors on short oil-film bearings of various types (cylindrical, pocket, symmetrical three-lobed, unsymmetrical three-lobed). As a first step, the conventional parallel, angular and combined parallel and angular misalignments are modelled using Lagrange multipliers. The static equilibrium position of the journal within the bearing is determined using an iterative nonlinear static finite element analysis. The present work proposes a method for computing the displacement-dependent stiffness terms from the experimental static loaddisplacement data. Finally, the orbit of the rotor around the static equilibrium is determined using a time-integration scheme.

    • Experimental investigation of separated shear layer from a leading edge subjected to various angles of attack with tail flap deflections

      K Anand S Sarkar

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      Shear layer development over a thick flat plate with a semi-circular leading edge is investigated for a range of angles of attack under different pressure gradients for a Reynolds number of 2.44×105 (based on chord and free-stream velocity). The characteristics of the separated shear layer are very well documented through a combination of surface pressure measurement and smoke flow visualization. The instability of the separated layer occurs because of enhanced receptivity of perturbations leading to the development of significant unsteadiness and three-dimensional motions in the second-half of the bubble. The onset of separation, transition and the point of reattachment are identified for varying angles of attack and pressure gradients imposed by tail flap deflections. The data concerning bubble length, laminar portion and reattachment points agree well with the literature.

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