K. Narayanasamy

Bio: K. Narayanasamy is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Axial piston pump & Radial piston pump. The author has an hindex of 2, co-authored 2 publications receiving 29 citations.

On the efficiency of the axial piston motor considering piston form deviations

Abstract: Axial piston motors rely on a close fit of piston to bore to minimise leakage past the piston due to axial pressure drop. Machining imperfections in the cylinder bore and the piston change the clearance between them, affecting the performance of the motor. The effect of machining imperfections like out-of-roundness and taper in the piston on the mechanical and volumetric efficiency of the motor, in the speed range where the viscous friction is dominant, are studied. Experiments to measure torque and leakage flow are conducted on a fixed displacement swash plate type axial piston hydraulic motor and results are presented.

Piston eccentricity and friction force measurement in a hydraulic cylinder in dynamic conditions considering the form deviations on a piston

Abstract: Geometrical imperfections on pistons cause an asymmetric pressure distribution in the clearance between the piston and cylinder bore. Due to this, the piston attains different eccentricity positions during a stroke. The eccentricity of the piston affects the performance of the cylinder by influencing the frictional and leakage aspects. A compact mechatronic test rig is designed and fabricated to measure the piston eccentricity and friction in a dynamic condition. Pistons of defined geometric profiles such as elliptic and three-lobe are fabricated using a machining center. These pistons have been introduced into the test rig. The eccentricity and dynamic friction tests are conducted at various operating conditions and the results are presented and analysed.

Homogenous charge compression ignition and barrel engines

Abstract: A homogenous charge compression ignition barrel engine includes an engine housing with a first and second end. An elongated power shaft is longitudinally disposed in the engine housing and defines a longitudinal axis of the engine. A plurality of cylinders surround the longitudinal axis with each cylinder having a closed end and an open end. Each cylinder has a central axis. The open ends of the cylinders are each generally directed toward the first end of the housing. An intake system is operable to introduce a combustible mixture of air and fuel into each of the cylinders. A track is disposed between the first end of the housing and the open ends of the cylinders such that a portion of the track is disposed generally in alignment with the central axis of each of the cylinders. The track has a cam surface that longitudinally undulates with respect to the open ends of the cylinders. A portion of the cam surface is disposed generally in alignment with the central axis of each of the cylinders. The track and the cylinders are rotatable with respect to each other such that the undulating cam surface moves with respect to the open ends of the cylinders. A piston is moveably disposed in each of the cylinders such that a combustion chamber is defined between the piston and the closed end of the cylinder. Each piston is in mechanical communication with the cam surface of the track such that as the cylinders and the track move with respect to each other, the pistons reciprocate within the cylinders. Each cylinder is operable to compress a combustible mixture until the mixture auto ignites, without the introduction of a spark.

The effect of piston grooves performance in an axial piston pumps via CFD analysis

Abstract: In the design of high pressure piston pumps/motors, some manufacturers use pistons which have grooves being cut along the piston length, while others do not use grooves at all. The present paper clarifies the effect of grooves cut along the pistons surface via studding the effect of the number of grooves and their location over the piston surface. Piston force, torque, leakage, areas where cavitation might appear and piston stability, will be, in the present paper and for a set of piston/grooves configurations, carefully evaluated. A finite volume based Reynolds equation model has been formulated for the piston–cylinder clearance which considers the piston eccentricity and the relative tangential movement between piston and barrel. Different grooves configurations have been evaluated in search of finding minimum leakage, minimum appearance of cavitation and maximum restoring torque. Design instructions to optimize the piston behavior are also given, therefore the information and methodology presented in the present paper, is expected to be used as a designing tool for future machines. The piston/cylinder leakage is considered as laminar under all working conditions. The Fluid used is hydraulic oil ISO 32.

Investigation of the gap flow in displacement machines considering elastohydrodynamic effect

Abstract: The design of individual lubricating gaps with their bearing and sealing function mainly determines the loss behaviour, life time, reliability and achievable technical parameters of displacement machines. The gap flow conditions are influenced by the operating parameters, the gap macro geometry, the surface quality and by the chosen surface material. Therefore the determination of the time dependent gap height requires very complex simulation models considering the motion of moveable parts, the interaction between machine parts, the dependency on design and operating parameters and the energy dissipation within the gaps as well as changes of the gap height caused by the flexibility of the applied surface material. This paper introduces a new method for complex gap flow simulation of connected and self-adjusting gaps of axial piston machines, where the model for the piston/cylinder pair was extended to consider elastohydrodynamic effects. The simulation model has been verified with the help of friction force measurements on the piston/cylinder assembly.

Single-ended barrel engine with double-ended, double roller pistons

Abstract: An internal combustion barrel engine includes an engine housing with a first and second end An elongated power shaft is longitudinally disposed in the engine housing and defines a longitudinal axis A combustion cylinder and a guide cylinder are spaced apart and disposed on a common cylinder axis that is generally parallel to the central axis The cylinders each have an inner end and an outer end, with the inner ends being closer to each other The outer end of the combustion cylinder is closed An intake system is operable to introduce a mixture of air and/or fuel into the combustion cylinder A track is supported between the inner ends of the cylinders and has an undulating cam surface The track is moveable such that the portion of the cam surface most directly between the cylinders undulates toward and away from the inner end of the combustion cylinder A double-ended piston includes a combustion end disposed in the combustion cylinder so as to define a combustion chamber between the combustion end and the closed end of the combustion cylinder A guide end is disposed in the guide cylinder A midportion extends between the combustion end and the guide end and is in mechanical communication with the guide surface of the track A variable compression ratio device is operable to move the track axially towards and away from the inner end of the combustion cylinder so as to adjust the compression ratio Combustion occurs only in the combustion cylinder and does not occur in the guide cylinder

Numerical and experimental investigation on torque characteristics of seawater hydraulic axial piston motor for underwater tool system

Abstract: Seawater hydraulic axial piston motor is an important and elemental component in underwater tool system. The torque characteristics for a swash-plate-type seawater hydraulic axial piston motor is investigated, and an integrated torque model for the motor with symmetrical pre-compression angles has been developed, which consists of a torque sub-model and a dynamic pressure sub-model. Numerical simulations have been carried out to examine the effects of (a) pre-compression angle, (b) relief-groove obliquity, (c) motor speed, (d) piston chamber dead volume, (e) friction on the dynamic pressure and the output torque characteristics. The results indicate that the pre-compression angle, the friction coefficient, and the clearance between cylinder bore/piston have significant impact on the torque characteristics. The test verification has been undertaken with a five piston water hydraulic motor. This research contributes to the mechanism of output-torque fluctuation in a swash-plate-type seawater hydraulic axial piston motor, as well as the investigation of the torque transition phenomenon owing to the pre-compression angle. The research has laid the foundation for the development and improvement of the seawater hydraulic axial piston motor in underwater tool system.