Library

2573 match your search

The objective of the present work is to investigate numerically the 3D flow within diesel injector-like geometry using a cavitation model implemented in a commercial CFD code. A comprehensive study of various numerical parameters is performed which can subsequently be used to simulate cavitation under realistic diesel engine conditions.Numerical predictions were performed on a throttle channel at different operating conditions, with and without cavitation , and compared to available experimental measurements. Overall , it was found that the cavitation model was able to predict the onset of...
A RANS based computational fluid dynamics method incorporating the free-surface Volume of Fluid (VOF) multiphase flow has been employed to compute the resistance forces of two idealized seatrain concepts for fixed flotation as well as for two degrees of freedom (DOF) independent motion of each unit. The motion of each unit is analyzed using Dynamic Fluid Body Interaction (DFBI) morphing mesh technique. Seatrain, a series of hulls connected with rigid (except for pitch and heave) links is a potentially valuable concept for the Army Sealift, the Marine Corps as well as a broad spectrum of...
Unstructured grid generators are becoming more popular among engineers, due to the significant amount of time that can be saved by using them. They provide a great flexibility in the treatment of any kind of geometry, with minimal interaction from the user. However, it is important that the user selects an appropriate cell shape from the list of available cell topologies supported by the simulation tool. This important choice depends on a combination of flow physics, available computational resources and the complexity of the geometry. Applying a proper mesh configuration to CFD simulations...
In this study a semi-reduced reaction scheme developed previously was used to derive a 26 step reduced mechanism, using the sensitivity approach and the steady state approximation (QSS) with Chemkin code. This 26 step model has been implemented in a CFD combustion code (STAR-CD/Kinetics) to study combustion process in homogeneous charge compression ignition (HCCI) engines. The first results obtained have confirmed the very rapid combustion phase and fast heat release with completely homogeneous mixtures, for a wide range of operating conditions. This numerical approach has been used first to...
The objective of the present investigations was to identify the fundamental aerodynamic issues of residential wind-power systems based on rooftop wind panels with horizontal rotors. Numerical investigations were performed for (a) a single high efficiency wind turbine placed in a cross flow, (b) a model roof-top placed in a cross flow, and finally, after the identification of the optimum roof-top location for placing the wind turbine, (c) simulations of the roof-top panel with multiple horizontal rotors. Numerical results are presented for two cases of wind turbine blades being aligned or at...
Minimum fluidization velocity is one of the most important properties to characterize a bed, differentiating between a packed bed and a fluidized bed. Numerical simulation for 4 different ratios of initial bed heights (H) to base diameter (D), were performed; viz. 0.5, 1, 2 and 3. Glass beads of density 2600kg/m3 and with an average diameter of 550μm were used for all the simulations. Simulations were performed using the commercial CFD software, STAR-CCM+. The minimum fluidization velocity was identified by measuring pressure drop across the entire domain. The predicted minimum fluidization...
The commercial CFD code STAR-CD v4.02 is used as a numerical simulation tool for flows in the supercritical water-cooled nuclear reactor (SCWR). The basic heat transfer element in the reactor core can be considered as round rods and rod bundles. Reactors with vertical or horizontal flow in the core can be found. In vertically oriented core, symmetric characters of flow and heat transfer can be found and two-dimensional analyses are often performed. However, in horizontally oriented core the flow and heat transfer are fully three-dimensional due to the buoyancy effect. In this paper,...
This paper investigates a mean reaction rate closure for turbulent reacting flows called the Direct Quadrature Method of Moments using the Interaction by Exchange with the Mean micromixing model (DQMoM-IEM). The method was first introduced for reacting flows by Fox (Computational Models for Turbulent Reacting Flows, Cambridge University Press, 2003). We present a systematic study that considers several important new aspects of the method. In particular we introduce a new analytic expression for the DQMoM-IEM source terms. We present a rigourous numerical investigation and discuss problems of...
The diameter effect on the heat transfer of supercritical water (SCW) flows in horizontal round tubes has been studied using computational fluid dynamics (CFD) technique. The numerical simulations are carried out by the STAR-CD solver combined with the user developed subroutines that control the numerical calculation procedures. Through the tests it is found that the discretization scheme using CD, LUD or MARS will not affect the accuracy of the numerical simulations. Through the diameter effect studies, it is found that the heat transfer of supercritical water flows in the horizontal round...
The present paper deals with noise produced by an orifice placed in a circular duct. Such noise is mainly generated by the orifice itself and by the unsteady flow and turbulence in the orifice wake. The main objective of the present work is to develop a numerical prediction tool for the acoustic energy level produced by the orifice placed in a ducted flow. The model is based on the solution of the Navier-Stokes equations, for the compressible turbulent flow, inside the duct and in the near-region outside the duct termination, and on the Ffowcs Williams-Hawkings surface method for the...

Pages