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Tayfun E Tezduyar - One of the best experts on this subject based on the ideXlab platform.
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computational methods for Parachute fluid structure interactions
Archives of Computational Methods in Engineering, 2012Co-Authors: Kenji Takizawa, Tayfun E TezduyarAbstract:The computational challenges posed by fluid–structure interaction (FSI) modeling of Parachutes include the lightness of the Parachute canopy compared to the air masses involved in the Parachute dynamics, in the case of “ringsail” Parachutes the geometric complexities created by the construction of the canopy from “rings” and “sails” with hundreds of ring “gaps” and sail “slits”, and in the case of Parachute clusters the contact between the Parachutes. The Team for Advanced Flow Simulation and Modeling (Open image in new window) has successfully addressed these computational challenges with the Stabilized Space–Time FSI (SSTFSI) technique, which was developed and improved over the years by the Open image in new window and serves as the core numerical technology, and a number of special techniques developed in conjunction with the SSTFSI technique. The quasi-direct and direct coupling techniques developed by the Open image in new window, which are applicable to cases with incompatible fluid and structure meshes at the interface, yield more robust algorithms for FSI computations where the structure is light and therefore more sensitive to the variations in the fluid dynamics forces. The special technique used in dealing with the geometric complexities of the rings and sails is the Homogenized Modeling of Geometric Porosity, which was developed and improved in recent years by the Open image in new window. The Surface-Edge-Node Contact Tracking (SENCT) technique was introduced by the Open image in new window as a contact algorithm where the objective is to prevent the structural surfaces from coming closer than a minimum distance in an FSI computation. The recently-introduced conservative version of the SENCT technique is more robust and is now an essential technology in the Parachute cluster computations carried out by the Open image in new window. We provide an overview of the core and special techniques developed by the Open image in new window, present single-Parachute FSI computations carried out for design-parameter studies, and report FSI computation and dynamical analysis of two-Parachute clusters.
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fluid structure interaction modeling of spacecraft Parachutes for simulation based design
Journal of Applied Mechanics, 2012Co-Authors: Kenji Takizawa, Timothy Spielman, Creighton Moorman, Tayfun E TezduyarAbstract:Even though computer modeling of spacecraft Parachutes involves a number of numerical challenges, advanced techniques developed in recent years for fluid– structure interaction (FSI) modeling in general and for Parachute FSI modeling specifically have made simulationbased design studies possible. In this paper we focus on such studies for a single main Parachute to be used with the Orion spacecraft. Although these large Parachutes are typically used in clusters of two or three Parachutes, studies for a single Parachute can still provide valuable information for performance analysis and design and can be rather extensive. The major challenges in computer modeling of a single spacecraft Parachute are the FSI between the air and the Parachute canopy and the geometric complexities created by the construction of the Parachute from “rings” and “sails” with hundreds of gaps and slits. The Team for Advanced Flow Simulation and Modeling has successfully addressed the computational challenges related to the FSI and geometric complexities, and has also been devising special procedures as needed for specific design parameter studies. In this paper we present parametric studies based on the suspension line length, canopy loading and the length of the over-inflation control line.
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fluid structure interactions of a cross Parachute numerical simulation
Computer Methods in Applied Mechanics and Engineering, 2001Co-Authors: Keith Stein, Richard Benney, Tayfun E Tezduyar, Jean PotvinAbstract:Abstract The dynamics of Parachutes involves complex interaction between the Parachute structure and the surrounding flow field. Accurate representation of Parachute systems requires treatment of the problem as a fluid–structure interaction (FSI). In this paper we present the numerical simulations we performed for the purpose of comparison to a series of cross-Parachute wind tunnel experiments. The FSI model consists of a 3-D fluid dynamics (FD) solver based on the Deforming-Spatial-Domain/Stabilized Space–Time (DSD/SST) procedure, a structural dynamics (SD) solver, and a method of coupling the two solvers. These FSI simulations include the prediction of the coupled FD and SD behavior, drag histories, flow fields, structural behavior, and equilibrium geometries for the structure. Comparisons between the numerical results and the wind tunnel data are conducted for three cross-Parachute models and at three different wind tunnel flow speeds.
John W Leonard - One of the best experts on this subject based on the ideXlab platform.
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analysis of geometrically nonlinear anisotropic membranes application to pneumatic muscle actuators
Finite Elements in Analysis and Design, 2005Co-Authors: Wenqing Zhang, Michael L Accorsi, John W LeonardAbstract:Pneumatic muscle actuators are effective devices to generate tension forces by converting pneumatic energy into mechanical energy. They are currently being used in Parachute systems for soft-landing and steering control applications. Therefore, the simulation of their nonlinear structural dynamic behavior is necessary for a complete evaluation of these Parachute systems. In this paper, the working principles of pneumatic muscle actuators are reviewed; the application of pneumatic muscle actuators in Parachute systems for soft-landing and steering control is described; and a new finite element model for pneumatic muscle actuators is presented. Geometrically nonlinear anisotropic membrane elements are used in this model to simulate the nonlinear structural dynamic behavior of pneumatic muscle actuators, which is different from previous approaches. A quasi-static pneumatic muscle actuator model is analyzed for validation and two dynamic applications of pneumatic muscle actuators in Parachute systems are also presented.
Muppidi Suman - One of the best experts on this subject based on the ideXlab platform.
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Aerodynamic Performance of Supersonic Parachutes Behind Slender Bodies
2019Co-Authors: Van Norman John, O'farrell Clara, Clark Ian, Muppidi SumanAbstract:NASA's ASPIRE (Advanced Supersonic Parachute Inflation Research Experiments) project was launched to investigate the supersonic deployment, inflation and aerodynamics of full-scale disk-gap-band (DGB) Parachutes. Three flight tests (October 2017, March 2018 and July 2018) deployed and examined Parachutes meant for the upcoming "Mars 2020" mission. Mars-relevant conditions were achieved by performing the tests at high altitudes over Earth on a sounding rocket platform, with the Parachute deploying behind a slender body (roughly 1/6-th the diameter of the capsule that will use this Parachute for descent at Mars). All three tests were successful and delivered valuable data and imagery on Parachute deployment and performance. CFD simulations were used in designing the flight test, interpreting the flight data, and extrapolating the results obtained during the flight test to predict Parachute behavior at Mars behind a blunt capsule. This presentation will provide a brief overview of the test program and flight test data, with emphasis on differences in Parachute performance due to the leading body geometry
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ASPIRE Aerodynamic Models and Flight Performance
2019Co-Authors: Clark, Ian G., O'farrell Clara, Van Norman, John W., Muppidi SumanAbstract:The Advanced Supersonic Parachute Inflation Research Experiments (ASPIRE) project waslaunched to develop the capability for testing supersonic Parachutes at Mars-relevant conditions.Three initial Parachute tests, targeted as a risk-reduction activity for NASA's upcomingMars2020 mission, successfully tested two candidate Parachute designs and provided valuabledata on Parachute inflation, forces, and aerodynamic behavior. Design of the flight tests dependedon flight mechanics simulations which in turn required aerodynamic models for the payload, andthe Parachute. Computational Fluid Dynamics (CFD) was used to generate these models preflightand are compared against the flight data after the tests. For the payload, the reconstructedaerodynamic behavior is close to the pre-flight predictions, but the uncertainties in thereconstructed data are high due to the low dynamic pressures and accelerations during the flightperiod of comparison. For the Parachute, the predicted time to inflation agrees well with the preflightmodel; the peak aerodynamic force and the steady state drag on the Parachute are withinthe bounds of the pre-flight models, even as the models over-predict the Parachute drag atsupersonic Mach numbers. Notably, the flight data does not show the transonic drag decreasepredicted by the pre-flight model. The ASPIRE flight tests provide previously unavailablevaluable data on the performance of a large full-scale Parachute behind a slender leading bodyat Mars-relevant Mach number, dynamic pressure and Parachute loads. This data is used topropose a new model for the Parachute drag behind slender bodies to aid future experiments
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Performance of Supersonic Parachutes Behind Slender Bodies
2018Co-Authors: Van Norman John, O'farrell Clara, Muppidi Suman, Clark IanAbstract:NASAs ASPIRE (Advanced Supersonic Parachute Inflation Research Experiments) project is investigating the supersonic deployment, inflation and aerodynamics of full-scale disk-gap-band (DGB) Parachutes. The first two flight tests were carried out in October 2017 and March 2018, while a third test is planned for the fall of 2018. In these tests, Mars-relevant conditions are achieved by deploying the Parachutes at high altitudes over Earth using a sounding rocket test platform. As a result, the Parachute is deployed behind a slender body (roughly 1/6-th the diameter of the capsule that will use this Parachute for descent at Mars). Because there is limited flight and experimental data for supersonic DGBs behind slender bodies, the development of the Parachute aerodynamic models was informed by CFD simulations of both the leading body wake and the Parachute canopy. This presentation will describe the development of the pre-flight Parachute aerodynamic models and compare pre-flight predictions with the reconstructed performance of the Parachute during the flight tests. Specific attention will be paid to the differences in Parachute performance behind blunt and slender bodies
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Modeling and Flight Performance of Supersonic Disk-Gap-Band Parachutes in Slender Body Wakes
2018Co-Authors: Muppidi Suman, Clark Ian, Tanner Christopher, O'farrell ClaraAbstract:NASA's ASPIRE (Advanced Supersonic Parachute Inflation Research and Experiments) project is investigating the supersonic deployment and inflation of full-scale Parachutes. To achieve Mars-relevant conditions, the Parachutes are deployed at high altitudes over Earth on a sounding rocket platform. During the flight test, Disk-Gap-Band Parachutes of 21.5 meter diameter are deployed behind a slender payload 1/6th the diameter of the blunt Mars2020 capsule. Due to the differences in leading body geometry between the test flight and a Parachute deployment at Mars, high fidelity numerical simulations of slender and blunt bodywakes, and of rigid Parachutes behind them, were used to understand differences and similarities in the flow and the effect on Parachute drag. The slender body wake is thinner, closes earlier, and presents a smaller wake deficit. Thus, a Parachute deployed in the wake of a slender body is more likely to see a higher dynamic pressure than a Parachute deployed behind a blunt body. In the presence of a Parachute, the interaction of the unsteady wake with the Parachute bow shock is stronger behind the blunt body. Simulations yield highly unsteady forces on the Parachute, which was modeled as a rigid body. The mean Parachute force behind a slender body is between 3 and 12 percent higher than behind a blunt body, depending on the angle of the Parachute with the flow. As the angle of incidence increases, more of the Parachute moves out of the leading body wakes, decreasing the sensitivity to leading body shape. To compare the flow past Parachutes in Earth's and Mars' atmospheres, simulations were also performed in CO2. At the Mach number considered (1.75), the shock standoff distance ahead of the Parachute, post-shock jump conditions, and the resulting Parachute forces were found to be very similar in both air and CO2, indicating that a high altitude test is a good proxy for a Mars descent. The results of these numerical simulations and available data on past flight and wind tunnel tests of supersonic Disk-Gap-Band Parachutes behind slender bodies were used to generate a Parachute drag model for ASPIRE, which in turn was used to help design the flight test. The first flight test occurred in October 2017. The Parachute was successfully deployed at Mach 1.77 and an altitude of 42 kilometers. Test instrumentation provided the atmospheric conditions, test vehicle trajectory, and the loads on the Parachute along with detailed high-resolution imagery of the inflation process. Reconstruction of the flight test indicated that the measured forces on the Parachute were within the model's bounds, although the model over-predicted the Parachute force during the first few seconds. The Parachute forces during the long subsonic period were well-predicted by the ASPIRE drag model
O'farrell Clara - One of the best experts on this subject based on the ideXlab platform.
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Aerodynamic Performance of Supersonic Parachutes Behind Slender Bodies
2019Co-Authors: Van Norman John, O'farrell Clara, Clark Ian, Muppidi SumanAbstract:NASA's ASPIRE (Advanced Supersonic Parachute Inflation Research Experiments) project was launched to investigate the supersonic deployment, inflation and aerodynamics of full-scale disk-gap-band (DGB) Parachutes. Three flight tests (October 2017, March 2018 and July 2018) deployed and examined Parachutes meant for the upcoming "Mars 2020" mission. Mars-relevant conditions were achieved by performing the tests at high altitudes over Earth on a sounding rocket platform, with the Parachute deploying behind a slender body (roughly 1/6-th the diameter of the capsule that will use this Parachute for descent at Mars). All three tests were successful and delivered valuable data and imagery on Parachute deployment and performance. CFD simulations were used in designing the flight test, interpreting the flight data, and extrapolating the results obtained during the flight test to predict Parachute behavior at Mars behind a blunt capsule. This presentation will provide a brief overview of the test program and flight test data, with emphasis on differences in Parachute performance due to the leading body geometry
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ASPIRE Aerodynamic Models and Flight Performance
2019Co-Authors: Clark, Ian G., O'farrell Clara, Van Norman, John W., Muppidi SumanAbstract:The Advanced Supersonic Parachute Inflation Research Experiments (ASPIRE) project waslaunched to develop the capability for testing supersonic Parachutes at Mars-relevant conditions.Three initial Parachute tests, targeted as a risk-reduction activity for NASA's upcomingMars2020 mission, successfully tested two candidate Parachute designs and provided valuabledata on Parachute inflation, forces, and aerodynamic behavior. Design of the flight tests dependedon flight mechanics simulations which in turn required aerodynamic models for the payload, andthe Parachute. Computational Fluid Dynamics (CFD) was used to generate these models preflightand are compared against the flight data after the tests. For the payload, the reconstructedaerodynamic behavior is close to the pre-flight predictions, but the uncertainties in thereconstructed data are high due to the low dynamic pressures and accelerations during the flightperiod of comparison. For the Parachute, the predicted time to inflation agrees well with the preflightmodel; the peak aerodynamic force and the steady state drag on the Parachute are withinthe bounds of the pre-flight models, even as the models over-predict the Parachute drag atsupersonic Mach numbers. Notably, the flight data does not show the transonic drag decreasepredicted by the pre-flight model. The ASPIRE flight tests provide previously unavailablevaluable data on the performance of a large full-scale Parachute behind a slender leading bodyat Mars-relevant Mach number, dynamic pressure and Parachute loads. This data is used topropose a new model for the Parachute drag behind slender bodies to aid future experiments
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Performance of Supersonic Parachutes Behind Slender Bodies
2018Co-Authors: Van Norman John, O'farrell Clara, Muppidi Suman, Clark IanAbstract:NASAs ASPIRE (Advanced Supersonic Parachute Inflation Research Experiments) project is investigating the supersonic deployment, inflation and aerodynamics of full-scale disk-gap-band (DGB) Parachutes. The first two flight tests were carried out in October 2017 and March 2018, while a third test is planned for the fall of 2018. In these tests, Mars-relevant conditions are achieved by deploying the Parachutes at high altitudes over Earth using a sounding rocket test platform. As a result, the Parachute is deployed behind a slender body (roughly 1/6-th the diameter of the capsule that will use this Parachute for descent at Mars). Because there is limited flight and experimental data for supersonic DGBs behind slender bodies, the development of the Parachute aerodynamic models was informed by CFD simulations of both the leading body wake and the Parachute canopy. This presentation will describe the development of the pre-flight Parachute aerodynamic models and compare pre-flight predictions with the reconstructed performance of the Parachute during the flight tests. Specific attention will be paid to the differences in Parachute performance behind blunt and slender bodies
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Modeling and Flight Performance of Supersonic Disk-Gap-Band Parachutes in Slender Body Wakes
2018Co-Authors: Muppidi Suman, Clark Ian, Tanner Christopher, O'farrell ClaraAbstract:NASA's ASPIRE (Advanced Supersonic Parachute Inflation Research and Experiments) project is investigating the supersonic deployment and inflation of full-scale Parachutes. To achieve Mars-relevant conditions, the Parachutes are deployed at high altitudes over Earth on a sounding rocket platform. During the flight test, Disk-Gap-Band Parachutes of 21.5 meter diameter are deployed behind a slender payload 1/6th the diameter of the blunt Mars2020 capsule. Due to the differences in leading body geometry between the test flight and a Parachute deployment at Mars, high fidelity numerical simulations of slender and blunt bodywakes, and of rigid Parachutes behind them, were used to understand differences and similarities in the flow and the effect on Parachute drag. The slender body wake is thinner, closes earlier, and presents a smaller wake deficit. Thus, a Parachute deployed in the wake of a slender body is more likely to see a higher dynamic pressure than a Parachute deployed behind a blunt body. In the presence of a Parachute, the interaction of the unsteady wake with the Parachute bow shock is stronger behind the blunt body. Simulations yield highly unsteady forces on the Parachute, which was modeled as a rigid body. The mean Parachute force behind a slender body is between 3 and 12 percent higher than behind a blunt body, depending on the angle of the Parachute with the flow. As the angle of incidence increases, more of the Parachute moves out of the leading body wakes, decreasing the sensitivity to leading body shape. To compare the flow past Parachutes in Earth's and Mars' atmospheres, simulations were also performed in CO2. At the Mach number considered (1.75), the shock standoff distance ahead of the Parachute, post-shock jump conditions, and the resulting Parachute forces were found to be very similar in both air and CO2, indicating that a high altitude test is a good proxy for a Mars descent. The results of these numerical simulations and available data on past flight and wind tunnel tests of supersonic Disk-Gap-Band Parachutes behind slender bodies were used to generate a Parachute drag model for ASPIRE, which in turn was used to help design the flight test. The first flight test occurred in October 2017. The Parachute was successfully deployed at Mach 1.77 and an altitude of 42 kilometers. Test instrumentation provided the atmospheric conditions, test vehicle trajectory, and the loads on the Parachute along with detailed high-resolution imagery of the inflation process. Reconstruction of the flight test indicated that the measured forces on the Parachute were within the model's bounds, although the model over-predicted the Parachute force during the first few seconds. The Parachute forces during the long subsonic period were well-predicted by the ASPIRE drag model
Wenqing Zhang - One of the best experts on this subject based on the ideXlab platform.
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analysis of geometrically nonlinear anisotropic membranes application to pneumatic muscle actuators
Finite Elements in Analysis and Design, 2005Co-Authors: Wenqing Zhang, Michael L Accorsi, John W LeonardAbstract:Pneumatic muscle actuators are effective devices to generate tension forces by converting pneumatic energy into mechanical energy. They are currently being used in Parachute systems for soft-landing and steering control applications. Therefore, the simulation of their nonlinear structural dynamic behavior is necessary for a complete evaluation of these Parachute systems. In this paper, the working principles of pneumatic muscle actuators are reviewed; the application of pneumatic muscle actuators in Parachute systems for soft-landing and steering control is described; and a new finite element model for pneumatic muscle actuators is presented. Geometrically nonlinear anisotropic membrane elements are used in this model to simulate the nonlinear structural dynamic behavior of pneumatic muscle actuators, which is different from previous approaches. A quasi-static pneumatic muscle actuator model is analyzed for validation and two dynamic applications of pneumatic muscle actuators in Parachute systems are also presented.
