Applied Mechanics and Materials Vols. 592-594

Abstract: In this work, the pneumatic transport of coarse grain particles (alumina) through a horizontal pipe is considered. Corresponding flow of the mixture is assumed as a two-phase one-dimensional flow. The present work considers a air mass balance model. A MATLAB program is developed to update the governing equations. Since a good agreement is observed between the present prediction and the result available in the literature, the model is used for further investigation. The variation of pressure drop, velocity and mass flow rate along the length of pipe for both low and high volume flow rate is predicted. It is observed that the pneumatic transport of the alumina particles is permitted up to a limiting length of the pipe due to a huge pressure drop in the pipe at very high velocity. Corresponding limiting length of the pipe with different mixture velocities is predicted.

Abstract: Inspired by the propulsion of organisms in a viscous fluid, we develop a two-dimensional computational model to study the propulsive and fluid dynamic features of an organism modeled as an elastic filament in viscous fluid using immersed boundary (IB) finite volume method. The elastic filament is modeled using discrete number of IB points. The elastic forces are computed based on an elastic energy function. The Navier-Stokes equations governing the fluid flow are solved on a staggered Cartesian grid system using the fractional step based finite volume method. The computational model is validated by comparing the numerical simulation results pertinent to the swimming of an infinite with that of the existing analytical results. The interplay of propulsive and fluiddynamic features of the organism in the viscous fluid is well captured using the developed model.

Abstract: In this article, an attempt was made to investigate the contact mechanics phenomenon of the reciprocating hydraulic U-seal by measuring friction forces at various pressures and velocities. The inlet fluctuating pressure and the rod speed was simultaneously performed at the peak pressures of 10, 20 and 30MPa and the rod speeds of, 0.12, 0.3 and 0.5 m/s. The distribution of the contact pressure at the seal/rod interface was calculated along the contact surface at pressures of 10, 20 and 30MPa using FE model. Friction measurement of reciprocating seals by experimental results demonstrated that the velocity of the rod and seal pressure influences the seal performance considerably. Furthermore, the numerical analysis undertaken to determine the contact pressure to compute friction force was in good agreement with the experimental results.

Abstract: The ELAC 1 (ELliptical Aerodynamic Configuration 1) is basically Hypersonic space vehicle and first stage of TSTO (Two Stage To Orbit) destined to fly up to altitude of 35 Km with M_∞=7 (Free stream Mach No.). In this paper, the comparison between the experimental data available at RWTH, Aachen and Polyhedral Unstructured Navier-Stokes solver simulations are made. The different AOA (Angles of attack) 0̊, 6̊ and 10̊ are considered with R_e = 3.6×10⁶ for the supersonic flow simulations. The various coefficients such as Aerodynamic coefficients, Pressure coefficients are compared with the wind tunnel data and the physics of the flow field is investigated.

Abstract: Air intake is a crucial component for supersonic and hypersonic air breathing propulsion devices. The intake must provide the required mass flow rate of air with minimal loss of stagnation pressure. A major difficulty in the stable operation of an intake is associated with shock wave boundary layer interaction (SBLI). This causes boundary layer separation and adverse pressure gradients which lead to total pressure loss, flow unsteadiness and flow distortion in the intake system. Passive control devices such as micro-ramp, thick-vanes provide better boundary layer control and reduce parasitic drag. The proposed study aims to perform CFD analysis of micro-ramp for hypersonic flows and validate the results with the available experimental data. Two micro ramp models namely MR80 and MR40 are considered for this study. Results obtained show the presence of micro ramp successfully delayed the flow separation and helped to suppress SBLI.

Abstract: This paper is concerned with the double-sided lid-driven cavity simulation of two-dimensional lattice kinetic scheme on the uniform lattice arrangement based on the standard lattice Boltzmann method. The double-sided lid-driven cavity problem has multiple steady solutions for some aspect ratios. However, for the double-sided square cavity no multiplicity of solutions has been observed for both the parallel and antiparallel motion of the walls. To validate this new lattice kinetic scheme, the numerical simulations of the double-sided square driven cavity flow at Reynolds numbers from 10 to 1000 are carried out. The Reynolds number effect on the flow structure is clearly manifested by the streamline patterns and velocity profiles. It is concluded that the present study in double-sided lid-driven cavity produces results that are in excellent conformity with earlier conventional numerical observations.

Abstract: Flow past a smooth circular cylinder at high Reynolds number (Re=3.6 x 10⁶) which covers the upper-transition regime has been investigated numerically by using Open source Field Operation and Manipulation (OpenFOAM) package. OpenFOAM is a free, open source Computational Fluid Dynamics (CFD) software package. The numerical model has been set up as two dimensional (2D), transient, incompressible and turbulent flow. A standard high Reynolds number k-ε turbulence model is included to evaluate the turbulence. The objective of the present work is to set up the case using pimpleFoam solver which is an Unsteady Reynolds Averaged Simulations (URANS) model and to evaluate the model for its conformance with available literature and experiments. The results obtained are compared with experimental and numerical data.

Abstract: The design, fabrication and calibration details of a miniature four hole probe for three-dimensional boundary layer measurements are presented in this paper. The probe has a nominal measuring area of 1 mm² and has a nominal dimension of 0.4 mm in the boundary layer direction thus minimizing pressure and velocity gradient errors and wall vicinity errors. The probe is calibrated in an open jet calibration tunnel at a velocity of 50 m/s in the yaw and pitch angle range of + 40^O at 5^O interval. The calibration coefficients are defined, calculated and presented. The sensitivity of the calibration coefficients is also calculated and presented.

Abstract: Directional control valves start, stop or change the direction of flow in compressed air applications. To understand the different applications of compressed air and how valves are used, one must first have knowledge of the kinds and types of valves used by industries. This paper studies local valve control of the electro-hydraulic system. The slow response of hydraulic control valve usually becomes the hold-up of whole system performance. Although fast valves (e.g. high-bandwidth servo-valves) are available, they are far more expensive than slow valves (e.g. proportional directional control valves). To improve the performance of proportional directional control valves, three different types of controllers are synthesized. Firstly, based on the pole zero cancellation technique, an open loop compensator is designed which requires the accurate valve dynamic model information; Secondly, a full state feedback adaptive robust controller (ARC) is synthesized, which effectively takes into account the effect of parametric uncertainties and uncertain nonlinearities such as friction force and flow force. Finally, an output feedback ARC controller is synthesized to address the problem of un measurable states. Keywords: valve, hydraulic device, Simulink.

Abstract: Nanotechnology offers enormous potential for discovering new fundamental science, for creating new materials with unique and important properties, and for developing new technology. Nanotechnology deals with particles and system with dimensions of approximately 1 to 100 nanometers. Some aspects of nanomanufacturing technology facilities like nanofabrication, nanometrology requires extremely stable environment with very stringent limits of ground vibration. The ground vibrations induced due to road and rail traffic can affect the nanotechnology research activities, due to disturbances caused by the road and rail traffic induced ground vibrations on the nanotechnology processes and the measurements. The paper presents the study of road traffic and metro train induced ground vibration for establishment of nanomanufacturing technology facilities at CMTI. The road traffic and the metro train induced ground vibration were monitored inside the CMTI campus at surface level to identify the magnitude of ground vibration. The road traffic and the metro train induced ground vibrations are compared in comparison with the CMTI Nanotechnology Lab specifications. The metro train induced ground vibration levels are more in comparison to the road traffic induced ground vibration. The metro train induced ground vibration level exceeds the CMTI Nanotechnology Laboratory ground vibration specifications.