摘要 :
Active wing shaping, or morphing, of an aircraft wing has the potential to substantially improve aircraft efficiency. In recent years, several studies have sought to quantify the efficiency improvements possible through active win...
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Active wing shaping, or morphing, of an aircraft wing has the potential to substantially improve aircraft efficiency. In recent years, several studies have sought to quantify the efficiency improvements possible through active wing shaping, but relatively few have considered how it may affect the optimum flight-path trajectory. In this paper, we seek to characterize the fuel savings from active wing shaping over an approximate optimum flight trajectory. To accomplish this, we present a simple direct trajectory optimization framework that can be used to rapidly perform a large number of trajectory optimizations to explore the design space of aircraft employing active wing shaping controls and identify how wing shaping may affect the total aircraft fuel consumption. Example solutions are presented for the approximate optimal flight-path trajectory and fuel consumption of the NASA Ikhana high-endurance UAV configuration and the NASA Common Research Model configuration. Results indicate that the use of active wing-shaping controls for load alleviation can result in up to around 8% fuel savings over an optimized baseline design operating along the optimized trajectory. It is also shown that active wing shaping tends to favor optimal trajectories with lower velocity, higher lift coefficient, and higher lift-to-drag ratio than the baseline design.
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摘要 :
For a wing in steady level flight, the lift distribution that minimizes induced drag depends on a tradeoff between wingspan and wing-structure weight. In 1933, Prandtl suggested that tapered wings have an advantage over rectangula...
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For a wing in steady level flight, the lift distribution that minimizes induced drag depends on a tradeoff between wingspan and wing-structure weight. In 1933, Prandtl suggested that tapered wings have an advantage over rectangular wings due to this tradeoff. However, Prandtl's solutions were obtained using assumptions that correspond to rectangular wings. Therefore, his claim was not analytically proven by his 1933 publication. Here, an approach similar to Prandtl's is taken with more general approximations that apply to wings of arbitrary planform. This more general development is used to study Prandtl's claim about tapered wings. Closed-form solutions for the optimum wingspan and corresponding induced drag are presented for wings having elliptic and linearly-tapered planforms with constraints of fixed wing loading and maximum stress. It is shown that induced drag is minimized with a triangular planform, which gives a reduction in induced drag of up to 24.44% over the rectangular planform and up to 11.71% over the elliptic planform. Numerical solutions for the lift distributions that minimize induced drag for each planform are also presented. It is shown that the optimum lift distribution produces up to 5.94% less induced drag than the elliptic lift distribution when the triangular planform is used.
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摘要 :
For a wing in steady level flight, the lift distribution that minimizes induced drag depends on a tradeoff between wingspan and wing-structure weight. In 1933, Prandtl suggested that tapered wings have an advantage over rectangula...
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For a wing in steady level flight, the lift distribution that minimizes induced drag depends on a tradeoff between wingspan and wing-structure weight. In 1933, Prandtl suggested that tapered wings have an advantage over rectangular wings due to this tradeoff. However, Prandtl's solutions were obtained using assumptions that correspond to rectangular wings. Therefore, his claim was not analytically proven by his 1933 publication. Here, an approach similar to Prandtl's is taken with more general approximations that apply to wings of arbitrary planform. This more general development is used to study Prandtl's claim about tapered wings. Closed-form solutions for the optimum wingspan and corresponding induced drag are presented for wings having elliptic and linearly-tapered planforms with constraints of fixed wing loading and maximum stress. It is shown that induced drag is minimized with a triangular planform, which gives a reduction in induced drag of up to 24.44% over the rectangular planform and up to 11.71% over the elliptic planform. Numerical solutions for the lift distributions that minimize induced drag for each planform are also presented. It is shown that the optimum lift distribution produces up to 5.94% less induced drag than the elliptic lift distribution when the triangular planform is used.
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摘要 :
A characterization of the Common Research Model (CRM) wing for low-fidelity aerostructural optimization is presented. The geometric and structural properties are based on the CAD geometries and finite-element models for the CRM wi...
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A characterization of the Common Research Model (CRM) wing for low-fidelity aerostructural optimization is presented. The geometric and structural properties are based on the CAD geometries and finite-element models for the CRM wing and the undeflected Common Research Model Wing (uCRM). Three approximations are presented for the elastic axis from previously-published studies on wing boxes similar to the uCRM, and approximations of the flexural and torsional rigidity are presented from a previously-published study using the uCRM wing. The characterization presented in this paper is intended to be used within low-fidelity aerostructural analysis tools to facilitate rapid design optimization and exploratory studies using the CRM wing.
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摘要 :
A characterization of the Common Research Model (CRM) wing for low-fidelity aerostructural optimization is presented. The geometric and structural properties are based on the CAD geometries and finite-element models for the CRM wi...
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A characterization of the Common Research Model (CRM) wing for low-fidelity aerostructural optimization is presented. The geometric and structural properties are based on the CAD geometries and finite-element models for the CRM wing and the undeflected Common Research Model Wing (uCRM). Three approximations are presented for the elastic axis from previously-published studies on wing boxes similar to the uCRM, and approximations of the flexural and torsional rigidity are presented from a previously-published study using the uCRM wing. The characterization presented in this paper is intended to be used within low-fidelity aerostructural analysis tools to facilitate rapid design optimization and exploratory studies using the CRM wing.
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摘要 :
As contemporary aerostructural research in aircraft design trends toward high-fidelity computational methods, aerostructural solutions based on theory are often neglected or forgotten. In fact, in many modern aerostructural wing o...
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As contemporary aerostructural research in aircraft design trends toward high-fidelity computational methods, aerostructural solutions based on theory are often neglected or forgotten. In fact, in many modern aerostructural wing optimization studies, the elliptic lift distribution is used as a benchmark in place of theoretical aerostructural solutions with more appropriate constraints. In this paper, we review several theoretical aerostructural solutions that could be used as benchmark cases for wing design studies, and we compare them to high-fidelity solutions with similar constraints. Solutions are presented for studies with 1) constraints related to the wing integrated bending moment, 2) constraints related to the wing root bending moment, and 3) structural constraints combined with constraints on either wing stall or wing loading. It is shown that for each set of design constraints, the theoretical optimum lift distribution consistently shows excellent agreement with high-fidelity results. It follows that theoretical optimum lift distributions can often serve as a good benchmark for higher fidelity aerostructural wing optimization methods. Moreover, a review of solutions for the optimum wingspan and corresponding drag reveals important insights into the effects of viscosity, aeroelasticity, and compressibility on the aerodynamic and structural coupling involved in wing design and optimization.
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摘要 :
As contemporary aerostructural research in aircraft design trends toward high-fidelity computational methods, aerostructural solutions based on theory are often neglected or forgotten. In fact, in many modern aerostructural wing o...
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As contemporary aerostructural research in aircraft design trends toward high-fidelity computational methods, aerostructural solutions based on theory are often neglected or forgotten. In fact, in many modern aerostructural wing optimization studies, the elliptic lift distribution is used as a benchmark in place of theoretical aerostructural solutions with more appropriate constraints. In this paper, we review several theoretical aerostructural solutions that could be used as benchmark cases for wing design studies, and we compare them to high-fidelity solutions with similar constraints. Solutions are presented for studies with 1) constraints related to the wing integrated bending moment, 2) constraints related to the wing root bending moment, and 3) structural constraints combined with constraints on either wing stall or wing loading. It is shown that for each set of design constraints, the theoretical optimum lift distribution consistently shows excellent agreement with high-fidelity results. It follows that theoretical optimum lift distributions can often serve as a good benchmark for higher fidelity aerostructural wing optimization methods. Moreover, a review of solutions for the optimum wingspan and corresponding drag reveals important insights into the effects of viscosity, aeroelasticity, and compressibility on the aerodynamic and structural coupling involved in wing design and optimization.
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摘要 :
As contemporary aerostructural research in aircraft design trends toward high-fidelity computational methods, aerostructural solutions based on theory are often neglected or forgotten. In fact, in many modern aerostructural wing o...
展开
As contemporary aerostructural research in aircraft design trends toward high-fidelity computational methods, aerostructural solutions based on theory are often neglected or forgotten. In fact, in many modern aerostructural wing optimization studies, the elliptic lift distribution is used as a benchmark in place of theoretical aerostructural solutions with more appropriate constraints. In this paper, we review several theoretical aerostructural solutions that could be used as benchmark cases for wing design studies, and we compare them to high-fidelity solutions with similar constraints. Solutions are presented for studies with 1) constraints related to the wing integrated bending moment, 2) constraints related to the wing root bending moment, and 3) structural constraints combined with constraints on either wing stall or wing loading. It is shown that for each set of design constraints, the theoretical optimum lift distribution consistently shows excellent agreement with high-fidelity results. It follows that theoretical optimum lift distributions can often serve as a good benchmark for higher fidelity aerostructural wing optimization methods. Moreover, a review of solutions for the optimum wingspan and corresponding drag reveals important insights into the effects of viscosity, aeroelasticity, and compressibility on the aerodynamic and structural coupling involved in wing design and optimization.
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摘要 :
As contemporary aerostructural research in aircraft design trends toward high-fidelity computational methods, aerostructural solutions based on theory are often neglected or forgotten. In fact, in many modern aerostructural wing o...
展开
As contemporary aerostructural research in aircraft design trends toward high-fidelity computational methods, aerostructural solutions based on theory are often neglected or forgotten. In fact, in many modern aerostructural wing optimization studies, the elliptic lift distribution is used as a benchmark in place of theoretical aerostructural solutions with more appropriate constraints. In this paper, we review several theoretical aerostructural solutions that could be used as benchmark cases for wing design studies, and we compare them to high-fidelity solutions with similar constraints. Solutions are presented for studies with 1) constraints related to the wing integrated bending moment, 2) constraints related to the wing root bending moment, and 3) structural constraints combined with constraints on either wing stall or wing loading. It is shown that for each set of design constraints, the theoretical optimum lift distribution consistently shows excellent agreement with high-fidelity results. It follows that theoretical optimum lift distributions can often serve as a good benchmark for higher fidelity aerostructural wing optimization methods. Moreover, a review of solutions for the optimum wingspan and corresponding drag reveals important insights into the effects of viscosity, aeroelasticity, and compressibility on the aerodynamic and structural coupling involved in wing design and optimization.
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摘要 :
During early phases of wing design, analytic and low-fidelity methods are often used to identify promising design concepts. In many cases, solutions obtained using these methods provide intuition about the design space that is not...
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During early phases of wing design, analytic and low-fidelity methods are often used to identify promising design concepts. In many cases, solutions obtained using these methods provide intuition about the design space that is not easily obtained using higher-fidelity methods. This is especially true for aerostructural design. However, many analytic and low-fidelity aerostructural solutions are limited in application to wings with specific planforms and weight distributions. Here, a numerical method for minimizing induced drag with structural constraints is presented that uses approximations that apply to wings with arbitrary planforms and weight distributions. The method is applied to the NASA Ikhana airframe to show how it can be used for rapid aerostructural optimization and design-space exploration. The design space around the optimum solution is visualized, and the sensitivity of the optimum solution to changes in weight distribution, structural properties, wing loading, and taper ratio is shown. The optimum lift distribution and wing-structure weight for the Ikhana airframe are shown to be in good agreement with analytic solutions. Whereas most modern high-fidelity solvers obtain solutions in a matter of hours, all of the solutions shown here can be obtained in a matter of seconds.
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