scholarly journals Shape Optimization of the Cross-Section for Noncircular Hypersonic Missile Forebody

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Jingfan Chen ◽  
Xiaoqiang Fan ◽  
Bing Xiong ◽  
Yi Wang
Keyword(s):  
Shape Optimization ◽  
Cross Section ◽  
Parametric Modeling ◽  
Cross Section Shape ◽  
Section Shape ◽  
The Cross ◽  
Wide Speed Range ◽  
Optimization Efficiency ◽  
Drag Ratio ◽  
Lift To Drag Ratio

In the hypersonic regime, noncircular missiles have attracted significant attention from researchers. The paper first summarizes the development and present situation of the noncircular missiles at home and abroad. Previous research found that the cross-section shape of missiles has a direct influence on the aerodynamics performance. To find the best cross-section shape in terms of lift-drag-ratio, an efficient and robust shape optimization framework is developed. Class/shape function transformation (CST) method and power-law curve are introduced to complete the parametric modeling of the noncircular missile. The evolutionary algorithm has been utilized to improve the optimization efficiency. A combination of script and journal files is written to automate the CAD loft, mesh generation, and CFD simulations process. Finally, the forebody section of a missile body is chosen as an example to deliver the whole optimization steps. The optimization results show that the lift-to-drag ratio increases from 1.8 to 2.4 when the hypersonic missile forebody cruises at the design condition. The results also demonstrate that the optimized configuration has a better aerodynamic performance than the original one over a wide speed range from Mach 2 to 8 and a wide attack of angle range from 0 to 30.

scholarly journals Aerodynamic Performance of Biomimicry Snake-Shaped Airfoil

2019 ◽  
Vol 9 (2) ◽  
pp. 3319-3323
Keyword(s):  
Cross Section ◽  
Lift Coefficient ◽  
Design Parameters ◽  
Drag Forces ◽  
Cross Section Shape ◽  
Section Shape ◽  
Wide Range ◽  
Lift And Drag ◽  
Drag Ratio ◽  
Lift To Drag Ratio

The cross-section shape and proportionality between geometrical dimensions are the most important design parameters of any lifting surfaces. These parameters affect the amount of the aerodynamic forces that will be generated. In this study, the focus is placed on the snake-cross-section airfoil known as the S-airfoil. It is found that there is a lack of available researches on S-airfoil despite its important characteristics. A parametric study on empty model of the S-airfoil with a cross-section shape that is inspired by the Chrysopelea paradise snake is conducted through numerical simulation. Simulation using 2D-ANSYS FLUENT17 software is used to generate the lift and drag forces to determine the performance of airfoil aerodynamic. Based on the results, the S-airfoil can be improved in performance of aerodynamic by reducing the thickness at certain range, whereby changing the thickness-to-chord ratio from 0.037 to 0.011 results in the increment of lift-to-drag ratio from 2.629 to 3.257. On other hand, increasing the height-to-chord ratio of the S-airfoil will increase maximum lift coefficient but drawback is a wide range of angles of attack regarding maximum lift-to-drag ratio. Encouraging results obtained in this study draws attention to the importance of expanding the research on S-airfoil and its usage, especially in wind energy.

scholarly journals Designing for People’s Safety on Flooded Streets: Uncertainties and the Influence of the Cross-Section Shape, Roughness and Slopes on Hazard Criteria

Water ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2119
Author(s):  
Luís Mesquita David ◽  
Rita Fernandes de Carvalho
Keyword(s):  
Cross Section ◽  
Overland Flow ◽  
Rectangular Cross Section ◽  
Safety Hazard ◽  
Cross Section Shape ◽  
Section Shape ◽  
Flood Flows ◽  
The Cross ◽  
Flooding Risk

Designing for exceedance events consists in designing a continuous route for overland flow to deal with flows exceeding the sewer system’s capacity and to mitigate flooding risk. A review is carried out here on flood safety/hazard criteria, which generally establish thresholds for the water depth and flood velocity, or a relationship between them. The effects of the cross-section shape, roughness and slope of streets in meeting the criteria are evaluated based on equations, graphical results and one case study. An expedited method for the verification of safety criteria based solely on flow is presented, saving efforts in detailing models and increasing confidence in the results from simplified models. The method is valid for 0.1 m2/s 0.5 m2/s. The results showed that a street with a 1.8% slope, 75 m1/3s−1 and a rectangular cross-section complies with the threshold 0.3 m2/s for twice the flow of a street with the same width but with a conventional cross-section shape. The flow will be four times greater for a 15% street slope. The results also highlighted that the flood flows can vary significantly along the streets depending on the sewers’ roughness and the flow transfers between the major and minor systems, such that the effort detailing a street’s cross-section must be balanced with all of the other sources of uncertainty.

Oxidation of Suspended Stacked Silicon Nanowire for Sub-10nm Cross-Section Shape Optimization

2019 ◽  
Vol 13 (1) ◽  
pp. 195-199 ◽  
Author(s):  
Alexandre Hubert ◽  
Jean-Philippe Colonna ◽  
Stéphane Bécu ◽  
Cécilia Dupré ◽  
Virginie Maffini-Alvaro ◽  
...  
Keyword(s):  
Shape Optimization ◽  
Cross Section ◽  
Silicon Nanowire ◽  
Cross Section Shape ◽  
Section Shape

Finite-size analysis and the influence of the cross-section shape of the granular column collapses

2021 ◽  
Author(s):  
Teng Man ◽  
Herbert Huppert ◽  
Ling Li ◽  
Sergio Galindo-Torres
Keyword(s):  
Size Effect ◽  
Cross Section ◽  
Finite Size ◽  
Size Analysis ◽  
Cross Section Shape ◽  
Section Shape ◽  
The Cross ◽  
Shape Influence ◽  
Deposition Morphology ◽  
Granular Column

<p>The collapse of granular columns, which sheds light on the kinematics, dynamics, and deposition morphology of mass-driven flows, is crucial for understanding complex flows in both natural and engineering systems, such as debris flows and landslides. However, our research shows that a strong size effect and cross-section shape influence exist in this test. Thus, it is essential to better understand these effects. In this study, we explore the influence of both relative column sizes and cross-section shapes on the run-out behavior of collapsed granular columns and analyze their influence on the deposition morphology with the discrete element method (DEM) with Voronoi-based spheropolyhedron particles. We link the size effect that occurs in granular column collapse problems to the finite-size scaling functions and investigate the characteristic correlation length associated with the granular column collapses. The collapsing behavior of granular columns with different cross-section shapes is also studied, and we find that particles tend to accumulate in the direction normal to the edge of the cross-section instead of the vertex of it. The differences in the run-out behavior in different directions when the cross-section is no longer a circle can also be explained by the finite-size analysis we have performed in this study. We believe that such a study is crucial for us to better understand how granular material flows, how it deposits, and how to consider the size effect in the rheology of granular flows.</p>

Parametric study of the cross-section shape of aluminium tubes in dynamic three-point bending

2019 ◽  
Vol 136 ◽  
pp. 315-322 ◽  
Author(s):  
David Bilston ◽  
Dong Ruan ◽  
Artur Candido ◽  
Yvonne Durandet
Keyword(s):  
Cross Section ◽  
Parametric Study ◽  
Three Point Bending ◽  
Cross Section Shape ◽  
Section Shape ◽  
The Cross

scholarly journals Influence of the cross section shape on the behaviour of SRG-confined prismatic concrete specimens

2015 ◽  
Vol 49 (3) ◽  
pp. 869-887 ◽  
Author(s):  
Georgia E. Thermou ◽  
Konstantinos Katakalos ◽  
George Manos
Keyword(s):  
Cross Section ◽  
Cross Section Shape ◽  
Section Shape ◽  
The Cross

A note on the elastic contact stiffness of a layered medium

1993 ◽  
Vol 8 (12) ◽  
pp. 3229-3232 ◽  
Author(s):  
Huajian Gao ◽  
Tsai-Wei Wu
Keyword(s):  
Perturbation Method ◽  
Cross Section ◽  
Layered Medium ◽  
Contact Stiffness ◽  
Elastic Contact ◽  
Cross Section Shape ◽  
Section Shape ◽  
Cylindrical Punch ◽  
The Cross

A perturbation method is used to confirm that the elastic contact stiffness associated with a flat-ended punch indenting a layered medium is insensitive to the cross-section shape of the punch as long as the shape does not differ too much from a circle. This result supports the practice of modeling nonaxisymmetric indenters such as Vickers or Berkovich indenters as an axisymmetric flat-ended cylindrical punch.

Numerical Simulation of Acoustic Resonance in Closed Side Branch With Different Cross-Section Shapes

2018 ◽  
Author(s):  
Jiang LiuYi ◽  
Zhang Hong ◽  
Duan QingQuan
Keyword(s):  
Cross Section ◽  
Research Work ◽  
Branch Pipe ◽  
Acoustic Resonance ◽  
Side Branch ◽  
Pipeline System ◽  
Detached Eddy Simulation ◽  
Cross Section Shape ◽  
Section Shape ◽  
The Cross

There are many closed side branches in the gas conveying pipeline system. When the gas passes through the closed side branch, the shear layer will arouse the acoustic resonance in the closed side branch, which is harmful to the safe operation of the pipeline. The research work is insufficient about the influence of the cross-section shape of the closed side branch on acoustic resonance. Using the Detached-Eddy Simulation (DES) model, the acoustic resonance characteristics caused by the side branch pipe with different square cross-sections are simulated at the inlet boundary conditions of 25 m/s, 30 m/s and 35 m/s. The results show that in the center axis of the side branch, a 1/4 wavelength standing wave was formed, and the acoustic resonance occurs at a higher Strouhal number in circular branch. The cross-section shape of the side branch does not affect the acoustic resonance frequency, but it has a certain influence on the amplitude of pressure fluctuation and has a significant influence on the high-order frequency components.

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