Use Of Computational Fluid Dynamics Methods Research Articles

Optymalizacja procesu projektowego stałych urządzeń gaśniczych gazowych za pomocą metod numerycznych CFD

Computational fluid dynamics (CFD) is a modern tool used in engineering practice that can be used to optimize the design of fixed gaseous extinguishing systems (FGE-systems). The paper presents selected possibilities of practical application of numerical methods for evaluation of individual FGE-systems design parameters. The main feature of CFD modeling is the ability to obtain gas concentration distributions, flow directions of fire extinguishing mixture in a protected room and spatial distribution of air temperature, which is an important cognitive value of this method. The results show the potential for practical use of CFD methods in the modeling of extinguishing gas protection of real properties.

CFD simulation of hemispherical domes: structural flexibility and interference factors

The computational fluid dynamics (CFD) method is widely used today for determining the wind action on structures. Along with the CFD method the wind tunnel experiments are also employed to achieve this purpose. The cost and effort required for a wind tunnel test, however, is much higher than that of the CFD method; therefore, it is beneficial to extend and validate the use of CFD method to various classes and types of structures. This paper firstly compares the results of CFD method with the results of three series of wind tunnel tests available in the literature. Then, numerically the effect of structural flexibility and the neighbourhood of the objects on the wind pressure distribution coefficients are studied. Two and three half spheres are arranged sequentially and transversally. According to the CFD analysis, at a clear distance greater than 2.5 times the diameter of the (obstructing) dome, the wind dynamic interference effects on the reference hemisphere are diminished.

Analysis of a swimmer's hand and arm in steady flow conditions using computational fluid dynamics

Propulsive forces generated by swimmers’ hands and arms have, to date, been determined strictly through experimental testing. As an alternative to these complex and costly experiments, the present research has applied the numerical technique of computational fluid dynamics (CFD) to calculate the steady flow around a swimmer's hand and arm at various angles of attack. Force coefficients computed for the hand and arm compared well with steady-state coefficients determined experimentally. The simulations showed significant boundary layer separation from the arm and hand, suggesting that Bernoulli's equation should not be used to mathematically describe the lift generated by a swimmer. Additionally, “2D” lift was shown to be inaccurate for the arm at all angles of attack and for the hand near angles of attack of 90°. Such simulations serve to validate the chosen CFD techniques, and are an important first step towards the use of CFD methods for determining swimming hydrodynamic forces in more complex unsteady flow conditions.

Calibration of CFD Methods for High Mach Number Aeroengine Flowfields

The design and analysis of scramjet engines relies heavily on the use of Computational Fluid Dynamics (CFD) methods due to the lack of experimental facilities and engineering analysis techniques for high Mach number, high-temperature flows. This emphasis on CFD requires that the methods be calibrated through comparison with existing experimental data to determine their level of capability and range of applicability. At General Dynamics’ Fort Worth Division a level of confidence has been established in the use of CFD methods for scramjet flowfields. These methods include a Beam-Warming-based Unsteady Navier-Stokes (UNS) solver, a Beam-Warming-based Parabolized Navier-Stokes (PNS) solver, and a MacCormack-based PNS solver. Specifically, comparisons between CFD flowfields and experimental data for a blunt cone at Mach 10.6, an inlet at Mach 7.4, a combustor at Mach 2.4, and an axisymmetric plug nozzle at Mach 3.2 have been made. These calibrations show good overall agreement for wall pressures, integrated forces, and pressure, Mach number, and chemical species profiles. Examination of the disparities between the CFD and experimental results focuses concern on the treatment of boundary layer turbulence and finite rate chemistry. As a result, further developmental tasks are suggested, which, when complete, will further enhance the applicability of the subject CFD methods.