turbulence flow

One of the powerful tools for fire investigation is Computational Fluid Dynamics, which has the capability to predict all influential parameters in fire, such as temperature, velocity, pressure, toxic species, and radiation. However, this method requires validation to assess the accuracy of the results. This can be achieved by simulating and comparing the results with experimental data to evaluate the numerical accuracy and examine the validity of the governing models used in the simulation. In this study, the temperature conditions, velocity, and combustion species were investigated and analyzed in the geometry of the fire compartment, by comparing the results of two software, FDS and OpenFOAM. It was observed that both software have similar validation results, although OpenFOAM performs slightly better than FDS. For instance, the temperature and CO2 species results in OpenFOAM have a relative error of 22.4 and 16%, while FDS have a relative error of 24 and 31%.

In this paper, the inviscid and viscous ultrasonic flow field of a steam turbine blade with Denton method is investigated. The novelty of this paper is, improving Denton's finite volume method by adding the turbulence viscous term on 2-D modeling. This is an area that better understanding can lead to improved design. The unsteady Navier - Stokes equations govern the overall behavior of compressible viscous flow and treated by the time marching scheme. For simulation in FORTRAN is used the finite volume method for discrete and Baldwin - Lomax model for the effects of turbulence in viscous flow. Independency of the number of grid points are obtained. Pressure distribution has been validated with experimental data and on the shock zone show good correlation and reduction of numerical errors with experimental data.

The present study focuses on the flow around a horizontal axis wind turbine. Large Eddy Simulation has been employed in order to study the flow at different rotational speeds. Anisotropic residual stress tensor is driven by The Smagorinsky model. Three simulations were performed at different tip speed ratio of 3, 6 and 10. The acquired results are in good agreement with presented experimental data in literatures. It is also revealed that development of the wake is decreased when downstream velocity is increased along the horizontal line at different downstream distance of wind turbine. In addition, velocity defect behind the wind turbine is increased when tip speed ratio increases but the recovery of wake is happened faster. At rotational speed equals 6, minimum velocity is 54% of the initial velocity and maximum efficiency is 67% at the lateral section of wind tunnel where the tip of blade is located, while they are 26% and 68% respectively when rotational speed is 10. Turbulence intensity is increased by increasing Tip Speed Ratio while separated vortices from the blade are disappeared later. The effect of separated vortices from the blades of wind turbine are not seen when rotational speed is 3, while they are revealed at rotational speed of 6 and 10. As a result, it can be concluded that the effect of separated vortices are augmented when rotational speed is increased.