Download or read book A Computational Fluid Dynamics Study on the Aerodynamic Performance of Ram air Parachutes written by Angelo A. Fonseca Pazmiño and published by . This book was released on 2018 with total page 258 pages. Available in PDF, EPUB and Kindle. Book excerpt: The modeling of the ram-air parachute presents challenges in the prediction of the inflight geometry, as there is a strong interaction between the flow field and parachute structure. This thesis presents the development of a CAD design and CFD methodology to the simulation of ram-air parachutes in steady-state conditions. Starting from a 2D rib drawing, methods were developed to approximate the 3D geometry and efficiently model the parachute as a rigid and impermeable body. The use of distortions was implemented on a 2D, pseudo-2D, and 3D model to enhance their behavior during a real flight. The SST turbulence model was chosen for the modeling of these designs because of its suitability to predict flow separation and reattachment from adverse pressure gradients. The high complexity of the 3D model is handled using appropriate boundary conditions and cleaning geometric tools within the CFD software. Visualization of the fluid flow parameters such as lift and drag coefficients at different angles of attack allow to evaluate aerodynamic performance at the specified flight conditions and provide clear trends for best model shapes. The computational results were compared to other experimental and numerical studies.
Download or read book Finite Element Computation of the Dynamics of Large Ram Air Parachutes written by and published by . This book was released on 1999 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This research is aimed at simulation of the aerodynamics/dynamics of large parafoils. Parallel computation methods for 3D simulation of the dynamics and fluid dynamics of a parafoil, with prescribed, time-dependent shape changes were studied. The mathematical model was based on the time-dependent, 3D Navier-Stokes equations governing the incompressible flow around the parafoil, and Newton's law of motion governing the dynamics of the parafoil, with the aerodynamic forces acting on the parafoil, calculated from the flow field. The computational methods developed for these 3D simulations include a stabilized space-time finite element formulation to accommodate for the shape changes, special mesh generation and mesh moving strategies developed for this purpose, iterative solution techniques for the large, coupled nonlinear equation systems involved, and parallel implementation of all these methods on scalable computing systems.
Download or read book Parallel Three Dimensional Computation of Fluid Dynamics and Fluid Structure Interactions of Ram Air Parachutes written by National Aeronautics and Space Adm Nasa and published by . This book was released on 2018-10-18 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is a final report as far as our work at University of Minnesota is concerned. The report describes our research progress and accomplishments in development of high performance computing methods and tools for 3D finite element computation of aerodynamic characteristics and fluid-structure interactions (FSI) arising in airdrop systems, namely ram-air parachutes and round parachutes. This class of simulations involves complex geometries, flexible structural components, deforming fluid domains, and unsteady flow patterns. The key components of our simulation toolkit are a stabilized finite element flow solver, a nonlinear structural dynamics solver, an automatic mesh moving scheme, and an interface between the fluid and structural solvers; all of these have been developed within a parallel message-passing paradigm. Tezduyar, Tayfun E. Johnson Space Center NAG9-919...
Download or read book A Computational Model that Couples Aerodynamic and Structural Dynamic Behavior of Parachutes During the Opening Process written by Keith R. Stein and published by . This book was released on 1993 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: In parachute research, the canopy inflation process in the least understood and most complex to model. Unfortunately, it is during the opening process that the canopy often experiences the largest deformations and loadings. The complexity of modelling the opening process stems from the coupling between the structural dynamics of the canopy, lines and payload with the aerodynamics of the surrounding fluid medium. The addition of a computational capability to model the coupled opening behavior would greatly assist in the understanding of the canopy inflation process.
Download or read book An Assessment of Productive Computational Fluid Dynamics for Aerodynamic Design written by Milton E. Vaughn and published by . This book was released on 2008 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The U.S. Army Aviation and Missile Research, Development, and Engineering Center (AMRDEC) has been applying a Government-developed, productivity-oriented, Computational Fluid Dynamics (CFD) methodology to the aerodynamic design of Army missiles. This methodology, dubbed Enter Tunnel Analysis (ETA), uses a robust Euler solver and automated grid generation software to drastically reduce the time required to set up and execute flow field computations. ETA is described and applied to two hypervelocity missile configurations; one using a bent nose for aerodynamic control and the other using traditional canards. Comparisons are made with wind tunnel data to assess ETA's ability to produce meaningful results for use by aerodynamic designers."--Report documentation page.
Download or read book Computational Aerodynamic Modeling of Aerospace Vehicles written by Mehdi Ghoreyshi and published by MDPI. This book was released on 2019-03-08 with total page 294 pages. Available in PDF, EPUB and Kindle. Book excerpt: Currently, the use of computational fluid dynamics (CFD) solutions is considered as the state-of-the-art in the modeling of unsteady nonlinear flow physics and offers an early and improved understanding of air vehicle aerodynamics and stability and control characteristics. This Special Issue covers recent computational efforts on simulation of aerospace vehicles including fighter aircraft, rotorcraft, propeller driven vehicles, unmanned vehicle, projectiles, and air drop configurations. The complex flow physics of these configurations pose significant challenges in CFD modeling. Some of these challenges include prediction of vortical flows and shock waves, rapid maneuvering aircraft with fast moving control surfaces, and interactions between propellers and wing, fluid and structure, boundary layer and shock waves. Additional topic of interest in this Special Issue is the use of CFD tools in aircraft design and flight mechanics. The problem with these applications is the computational cost involved, particularly if this is viewed as a brute-force calculation of vehicle’s aerodynamics through its flight envelope. To make progress in routinely using of CFD in aircraft design, methods based on sampling, model updating and system identification should be considered.
Download or read book Computational Fluid Dynamics in Aeropropulsion written by Wing Ng and published by . This book was released on 1995 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt: Contains 19 papers given at the November 1995 symposium held in San Francisco, California. Topics include aeroelastic analysis of ducted rotors; prediction of the effect of diffuser width on the diffusion process in a radial vaneless diffuser; a solution adaptive unstructured mesh method for cascade flow calculations; low-speed turbine computation by pressure- correction and time marching methods; numerical investigation of the unstart phenomenon in an axisymmetric supersonic inlet; and CFD modeling of a gas turbine combustor air swirler effect. Indexed by author only. Annotation copyright by Book News, Inc., Portland, OR
Download or read book The Performance and Design of Ram air Gliding Parachutes written by J. S. Lingard and published by . This book was released on 1981 with total page 50 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Available literature on ram-air parachutes generally describe either experimental studies or the development of specific systems. Little fundamental analysis has been attempted. This Report reviews current knowledge and, where appropriate, formulates a theoretical basis for ram-air parachute design. Theoretical analysis fo inflation is found to be intractable due to the complication of reefing devices. A theoretical model for glide performance is developed from wing theory. Predictions compare favourably with experiment. Improvements in aerodynamic efficiency with increasing aspect ratio are largely negated by increased line drag. Optimum aspect ratio and line length and the potential for glide performance improvement are discussed. The effects of lift/draf ratio, wing laoding, control deflection, and wind, on rate of descent an dhorizontal velocity are demonstrated. Glide and control effectiveness are strongly influenced by rigging. A dynamic stability model is presented. Longitudinal control, flare and gust response are investigated. Stability is shown to increase with increasing altitutde, store mass and line length."--Summary, page 1.
Download or read book Computational Fluid Dynamics Modeling of Parachute Clusters written by and published by . This book was released on 1997 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: A computational tool that models the terminal descent characteristics of a single or a cluster of parachutes is a technology that is needed by parachute designers and engineers. As part of a technology program annex (TPA), a joint effort between the U.S. Army Natick Research, Development, and Engineering Center (RRDEC) and the U.S. Army Research Laboratory (ARL) to develop this computational tool is now under way. As a first effort, attempts are being made to analyze both two-dimensional (2- D) and three-dimensional (3-D) flow fields around a parachute using a coupling procedure in which the fluid dynamics are coupled to 2-D and 3-D structural dynamic (SD) codes. This effort uses computational fluid dynamic (CFD) codes to calculate a pressure field, which is then used as an input load for the SD code. Specifically, this report presents the methods and results of the flow field plus the structural characteristics of a single axisymmetric parachute and a 3-D gore configuration for the terminal descent velocity. Computed results have been obtained using the payload weight and unstretched constructed geometry of the canopies as input. Significant progress has been made in determining the terminal descent flow field along with the terminal shape of the parachute. A discussion of the fluid and structural dynamics codes, coupling procedure, and the associated technical difficulties is presented. Examples of the codes' current capabilities are shown.
Download or read book Technical Evaluation Report on the Fluid Dynamics Panel Symposium on Computational Methods For Aerodynamic Design Inverse and Optimization written by North Atlantic Treaty Organization. Advisory Group for Aerospace Research and Development and published by . This book was released on 1989 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Computational Fluid Dynamics Modeling of Parachute Clusters written by and published by . This book was released on 1997 with total page 33 pages. Available in PDF, EPUB and Kindle. Book excerpt: A computational tool that models the terminal descent characteristics of a single or a cluster of parachutes is a technology that is needed by parachute designers and engineers. As part of a technology program annex (TPA), a joint effort between the U.S. Army Natick Research, Development, and Engineering Center (RRDEC) and the U.S. Army Research Laboratory (ARL) to develop this computational tool is now under way. As a first effort, attempts are being made to analyze both two-dimensional (2- D) and three-dimensional (3-D) flow fields around a parachute using a coupling procedure in which the fluid dynamics are coupled to 2-D and 3-D structural dynamic (SD) codes. This effort uses computational fluid dynamic (CFD) codes to calculate a pressure field, which is then used as an input load for the SD code. Specifically, this report presents the methods and results of the flow field plus the structural characteristics of a single axisymmetric parachute and a 3-D gore configuration for the terminal descent velocity. Computed results have been obtained using the payload weight and unstretched constructed geometry of the canopies as input. Significant progress has been made in determining the terminal descent flow field along with the terminal shape of the parachute. A discussion of the fluid and structural dynamics codes, coupling procedure, and the associated technical difficulties is presented. Examples of the codes' current capabilities are shown.
Download or read book Computation of Flow Over a Full scale Ram air Parachute Canopy written by Ali Eslambolchi and published by . This book was released on 2012 with total page 97 pages. Available in PDF, EPUB and Kindle. Book excerpt: The steady, incompressible Navier-Stokes equations along with the equation Spalart-Allmaras, turbulence model were solved using a finite-volume flow solver, ANSYS Fluent, to simulate the full three-dimensional viscous flow field around a full-scale, rigid, MC-4 canopy model to compute the aerodynamic forces and moments on the canopy. For the zero side slip angle case the surprising aspect of the flow is the non-uniform low velocity regions below the canopy that correspond to the separation bubbles, also a thick boundary layer follows all the way to the trailing edge. The lift coefficient increases linearly with the angle of attack up to 12o with the lift curve slope of 0.0302 (per deg) and zero lift angle of attack of -4.3o. The lowest drag coefficient occurs at an angle of attack range of 0o to 2o. The largest lift-to-drag ratio is achieved at 10o angle of attack. For the non-zero side slip angle case the side force coefficient decreases not quite linearly with the side slip angle; this linear shape is more visible until 10o side slip angle with the side force curve slope of -0.0048 (per deg) and zero side force angle of 0.15o. Lift coefficient changes are very small with side slip angle. But, the drag coefficient is strongly dependent on the side slip angle; for 20o side slip angle drag coefficient is 1.4 times the value for zero side slip angle. The pitching moment coefficient increases with side slip angle; for 20o side slip angle this increase is about 48% compared to zero side slip. The rolling moment coefficient increases nearly linearly until 10o side slip angle, but after that the curve is not close to linear; the rolling moment coefficient for 20o side slip angle is 5.7 times the value for 5o side slip angle. The yawing moment coefficient increases linearly with side slip angle; the yawing moment coefficient for 20o side slip angle is 3.6 times value for 5o side slip angle. For the middle range of angle of attacks, the values of lift and drag coefficients are fairly close for the three-dimensional results and the extension of results from a previous two-dimensional study. Although the loads from a 2D study could not be used to accurately predict the loads on a full-scale 3D canopy and result in some error, they still can provide acceptable assumptions for engineering purposes as a much faster and cheaper method.
Download or read book Parachute Inflation written by Keith R. Stein and published by . This book was released on 1994 with total page 83 pages. Available in PDF, EPUB and Kindle. Book excerpt: In parachute research, canopy inflation is the least understood and most complex process to model. Unfortunately, it is during the opening process that the canopy experiences the largest deformations and loadings. The complexity of modeling the opening process stems from the coupling between the structural dynamics of the canopy, lines plus payload and the aerodynamics of the surrounding fluid medium. The addition of a computational capability to model the coupled opening behavior would greatly assist in understanding the canopy inflation process. Ongoing research at the U.S. Army Natick Research, Development and Engineering Center (Natick) focuses on this coupled problem. The solution to this problem will assist in the development of future U.S. Army airdrop systems, which include the capability of deploying at low altitudes and high speeds. This report describes research at Natick that currently involves coupling a computational fluid dynamics (CFD) code to a mass spring damper (MSD) parachute structural code. The model is described and results are presented.
Download or read book Les M thodes de Calcul Pour la Conception A rodynamique m thodes Inverses Et L optimization written by P. A. Henne and published by . This book was released on 1990 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Perspective of Computational Fluid Dynamics written by and published by . This book was released on 1986 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Parachute Inflation A Problem in Aeroelasticity written by and published by . This book was released on 1994 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt: In parachute research, canopy inflation is the least understood and most complex process to model. Unfortunately, it is during the opening process that the canopy experiences the largest deformations and loadings. The complexity of modeling the opening process stems from the coupling between the structural dynamics of the canopy, lines plus payload and the aerodynamics of the surrounding fluid medium. The addition of a computational capability to model the coupled opening behavior would greatly assist in understanding the canopy inflation process. Ongoing research at the U.S. Army Natick Research, Development and Engineering Center (Natick) focuses on this coupled problem. The solution to this problem will assist in the development of future U.S. Army airdrop systems, which include the capability of deploying at low altitudes and high speeds. This report describes research at Natick that currently involves coupling a computational fluid dynamics (CFD) code to a mass spring damper (MSD) parachute structural code. The model is described and results are presented.
Download or read book Computational Fluid Dynamics Based Enhanced Indicial Aerodynamic Models written by Jayanarayanan Sitaraman and published by . This book was released on 2000 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt:
