Author: Breno M. Castro
Publisher:
ISBN: 9781423526001
Category :
Languages : en
Pages : 149
Book Description
A numerical investigation of unsteady wind tunnel and ground interference effects is carried out in the time domain to study the transonic flutter characteristics of the NLR 7301 section inside a wind tunnel and the thrust generation characteristics of a NACA 0014 airfoil plunging near a ground plane. A parallelized, multi-block, deforming grid, unsteady flow-solver is coupled with a two-degree-of-freedom structural model. For the transonic flutter problem, two types of porous-wall boundary-conditions are implemented and tested for the boundaries representing the tunnel walls. The type of porous boundary condition is found to influence significantly both steady and unsteady solutions. Results show that the free-flight flutter behavior may differ significantly from the behavior found in a porous wind tunnel because of the strong dependence on the tunnel porosity parameter and the proximity of the walls. An analysis of the trailing edge boundary condition is performed for the airfoil in ground effect. The computations show that this boundary condition influences the solution only when non-linearities are present in the flow-field, although parameters averaged through a cycle of oscillation are not affected significantly. The same behavior is observed for the influence of the turbulence model on the fully-turbulent, unsteady computations. However, the best agreement with low Reynolds number, experimental data is obtained when the flow is assumed laminar and no turbulence model is applied.
Multi-Block Parallel Navier-Stokes Simulation of Unsteady Wind Tunnel and Ground Interference Effects
Author: Breno M. Castro
Publisher:
ISBN: 9781423526001
Category :
Languages : en
Pages : 149
Book Description
A numerical investigation of unsteady wind tunnel and ground interference effects is carried out in the time domain to study the transonic flutter characteristics of the NLR 7301 section inside a wind tunnel and the thrust generation characteristics of a NACA 0014 airfoil plunging near a ground plane. A parallelized, multi-block, deforming grid, unsteady flow-solver is coupled with a two-degree-of-freedom structural model. For the transonic flutter problem, two types of porous-wall boundary-conditions are implemented and tested for the boundaries representing the tunnel walls. The type of porous boundary condition is found to influence significantly both steady and unsteady solutions. Results show that the free-flight flutter behavior may differ significantly from the behavior found in a porous wind tunnel because of the strong dependence on the tunnel porosity parameter and the proximity of the walls. An analysis of the trailing edge boundary condition is performed for the airfoil in ground effect. The computations show that this boundary condition influences the solution only when non-linearities are present in the flow-field, although parameters averaged through a cycle of oscillation are not affected significantly. The same behavior is observed for the influence of the turbulence model on the fully-turbulent, unsteady computations. However, the best agreement with low Reynolds number, experimental data is obtained when the flow is assumed laminar and no turbulence model is applied.
Publisher:
ISBN: 9781423526001
Category :
Languages : en
Pages : 149
Book Description
A numerical investigation of unsteady wind tunnel and ground interference effects is carried out in the time domain to study the transonic flutter characteristics of the NLR 7301 section inside a wind tunnel and the thrust generation characteristics of a NACA 0014 airfoil plunging near a ground plane. A parallelized, multi-block, deforming grid, unsteady flow-solver is coupled with a two-degree-of-freedom structural model. For the transonic flutter problem, two types of porous-wall boundary-conditions are implemented and tested for the boundaries representing the tunnel walls. The type of porous boundary condition is found to influence significantly both steady and unsteady solutions. Results show that the free-flight flutter behavior may differ significantly from the behavior found in a porous wind tunnel because of the strong dependence on the tunnel porosity parameter and the proximity of the walls. An analysis of the trailing edge boundary condition is performed for the airfoil in ground effect. The computations show that this boundary condition influences the solution only when non-linearities are present in the flow-field, although parameters averaged through a cycle of oscillation are not affected significantly. The same behavior is observed for the influence of the turbulence model on the fully-turbulent, unsteady computations. However, the best agreement with low Reynolds number, experimental data is obtained when the flow is assumed laminar and no turbulence model is applied.
Bio-mechanisms of Swimming and Flying
Author: N. Kato
Publisher: Springer Science & Business Media
ISBN: 4431539514
Category : Science
Languages : en
Pages : 218
Book Description
Tens of thousands of different animal species live on this planet, having survived for millions of years through adaptation and evolution, which has given them a vast variety of structures and functions. Biomechanical studies of animals swimming and flying can aid understanding of the mechanisms that enable them to move effectively and efficiently in fluids . Based on such understandings and analyses, we can aim to develop environmentally friendly machines that emulate these natu ral movements. The Earth Summit in Rio de Janeiro in 1992 agreed major treaties on biological diversity, addressing the comb ined issues of environmental protection and fair and equitable economic development. With regard to coastal environments, increasing biological diversity has begun to play an important role in reestablishing stable and sustainable ecosystems. This approach has begun to influence research into the behavior of aquatic species, as an understanding of the history of an individual aquatic species is indispensable in constructing an environmental assessment mod el that includes the physical, chemical, and biological effects of that species . From an engineering viewpoint, studying nature's biological diversity is an opportunity to reconsider mechanical systems that were systematically constructed in the wake of the Industrial Revolution. We have been accumulating knowledge of the sys tems inherent in biological creatures and using that knowledge to create new, envi ronmentally friendly technologies.
Publisher: Springer Science & Business Media
ISBN: 4431539514
Category : Science
Languages : en
Pages : 218
Book Description
Tens of thousands of different animal species live on this planet, having survived for millions of years through adaptation and evolution, which has given them a vast variety of structures and functions. Biomechanical studies of animals swimming and flying can aid understanding of the mechanisms that enable them to move effectively and efficiently in fluids . Based on such understandings and analyses, we can aim to develop environmentally friendly machines that emulate these natu ral movements. The Earth Summit in Rio de Janeiro in 1992 agreed major treaties on biological diversity, addressing the comb ined issues of environmental protection and fair and equitable economic development. With regard to coastal environments, increasing biological diversity has begun to play an important role in reestablishing stable and sustainable ecosystems. This approach has begun to influence research into the behavior of aquatic species, as an understanding of the history of an individual aquatic species is indispensable in constructing an environmental assessment mod el that includes the physical, chemical, and biological effects of that species . From an engineering viewpoint, studying nature's biological diversity is an opportunity to reconsider mechanical systems that were systematically constructed in the wake of the Industrial Revolution. We have been accumulating knowledge of the sys tems inherent in biological creatures and using that knowledge to create new, envi ronmentally friendly technologies.