| || Numerical Simulations of Flow in a 3-D Supersonic Intake at High Mach Numbers
Author : Sivakumar, R.;Babu, V.
Source : Defence Science Journal ; Vol:56(4) ; 2006 ; pp 465-476
Subject : 629.7 Aeronautics
Keywords : Numerical simulations;Mass flow rate;Flow distortion;Bowshock;Cowl shock;owl lip
Abstract : Numerical simulations of the compressible, 3-D non reacting flow in the engine inlet section of a concept hypersonic air-breathing vehicle are presented. These simulations have been carried out using FLUENT. For all the results reported, the mesh has been refined to achieve areaaveraged wall y+ about 105. Mass flow rate through the intake and stagnation pressure recovery are used to compare the performance at various angles of attack. The calculations are able to predict the mode of air-intake operation (critical and subcritical) for different angles of attack. Flow distortion at the intake for various angles of attack is also calculated and discussed. The numerical results are validated by simulating the flow through a 2-D mixed compression hypersonic intake model and comparing with the experimental data.
| || Impact Analysis of Concrete Structural Components
Author : Murthy, A. Rama Chandra;Palani, G.S.;Iyer, Nagesh R.
Source : Defence Science Journal ; Vol:60(3) ; 2010 ; pp 307-319
Subject : 62 Engineering;Defence Science Journal
Keywords : Concrete structures;reinforced concrete;concrete material models;finite element analysis;impact loading;numerical simulations;impact analysis;compact behaviour
Abstract : This paper presents an overview on the concrete structural components subjected to impact loading. The review includes empirical formulae, analytical models, and numerical simulations. Various empirical formulae on penetration depth, perforation, and scabbing limits as well as their ranges of application have been provided. It has been observed that the information available on the validation of these models is limited. There is wider scope to study the performance of well known empirical formulae. Penetration resistance function play an important role in any analytical model. It has been observed that the major limitation is rigid projectile assumption. There is scope to develop new/improved analytical models to represent projectile characteristics. The numerical simulation of concrete structural components subjected to impact loads is a complex phenomenon. From the review, it is observed that employing appropriate material model for concrete, equation-of-state, contact algorithm and definition of yield surface plays significant role in the accurate simulation of concrete structural components. There is ample scope to develop improved methodologies in terms of development of material models and contact algorithms, which can be employed in nonlinear explicit finite element analysis of concrete structural components subjected to impact loading.