Wing Shape Optimization and Selecting Rational Re-Entry Trajectory for Reusable Spacecraft of Tourist Class

2021 ◽  
pp. 74-86
Author(s):  
E.R. Ashikhmina ◽  
P.V. Prosuntsov
Keyword(s):  
Shape Optimization ◽  
Leading Edge ◽  
Control Program ◽  
Wing Shape ◽  
Flight Speed ◽  
Sweep Angle ◽  
Maximum Heat ◽  
Supersonic Flight ◽  
Aerodynamic Quality

The article considers solving the interrelated problems of wing shape optimization and synthesis of the re-entry trajectory control law for the reusable spacecraft of tourist class. To ensure a high aerodynamic quality of the wing, increase its bearing properties, as well as improve the maneuverability and controllability of the spacecraft as a whole, the wing shape has been optimized for sub- and supersonic flight modes. The problem of minimizing the wing area is solved for subsonic flight speed while ensuring the level of lift sufficient for landing, with the introduction of restrictions on the minimum wing sweep angle. For supersonic flight speed, maximization of the aerodynamic quality of the wing is used as an objective function. The length and taper of the wing, leading-edge sweep angle, the size of the root and tip chords, and the position of the wing relative to the fuselage were chosen as variables. For the wing shape selected on the basis of the parametric analysis, the calculation of the dependences of the spacecraft aerodynamic coefficients on the Mach number, used for selecting a rational program for the descent control in the atmosphere, was carried out. The choice of a rational control program is made with restrictions on the level of overloads, kinetic pressure and maximum heat flux.

Investigation on the effect of leading edge tubercles of sweptback wing at low reynolds number

2020 ◽  
Vol 21 (6) ◽  
pp. 621
Author(s):  
Veerapathiran Thangaraj Gopinathan ◽  
John Bruce Ralphin Rose ◽  
Mohanram Surya
Keyword(s):  
Leading Edge ◽  
Reynolds Numbers ◽  
Sweep Angle ◽  
Laminar Separation ◽  
Low Reynolds Numbers ◽  
Flow Energy ◽  
Airplane Wing ◽  
Low Reynolds ◽  
Naca 0015 ◽  
Wing Performance

Aerodynamic efficiency of an airplane wing can be improved either by increasing its lift generation tendency or by reducing the drag. Recently, Bio-inspired designs have been received greater attention for the geometric modifications of airplane wings. One of the bio-inspired designs contains sinusoidal Humpback Whale (HW) tubercles, i.e., protuberances exist at the wing leading edge (LE). The tubercles have excellent flow control characteristics at low Reynolds numbers. The present work describes about the effect of tubercles on swept back wing performance at various Angle of Attack (AoA). NACA 0015 and NACA 4415 airfoils are used for swept back wing design with sweep angle about 30°. The modified wings (HUMP 0015 A, HUMP 0015 B, HUMP 4415 A, HUMP 4415 B) are designed with two amplitude to wavelength ratios (η) of 0.1 & 0.24 for the performance analysis. It is a novel effort to analyze the tubercle vortices along the span that induce additional flow energy especially, behind the tubercles peak and trough region. Subsequently, Co-efficient of Lift (CL), Co-efficient of Drag (CD) and boundary layer pressure gradients also predicted for modified and baseline (smooth LE) models in the pre & post-stall regimes. It was observed that the tubercles increase the performance of swept back wings by the enhanced CL/CD ratio in the pre-stall AoA region. Interestingly, the flow separation region behind the centerline of tubercles and formation of Laminar Separation Bubbles (LSB) were asymmetric because of the sweep.

scholarly journals A novel p-harmonic descent approach applied to fluid dynamic shape optimization

2021 ◽  
Author(s):  
Peter Marvin Müller ◽  
Niklas Kühl ◽  
Martin Siebenborn ◽  
Klaus Deckelnick ◽  
Michael Hinze ◽  
...  
Keyword(s):  
Shape Optimization ◽  
Large Deformations ◽  
Fluid Dynamic ◽  
Shape Optimisation ◽  
Shape Features ◽  
Floating Bodies ◽  
Novel Method ◽  
Sharp Corners ◽  
Dynamic Shape

AbstractWe introduce a novel method for the implementation of shape optimization for non-parameterized shapes in fluid dynamics applications, where we propose to use the shape derivative to determine deformation fields with the help of the $$p-$$ p - Laplacian for $$p > 2$$ p > 2 . This approach is closely related to the computation of steepest descent directions of the shape functional in the $$W^{1,\infty }-$$ W 1 , ∞ - topology and refers to the recent publication Deckelnick et al. (A novel $$W^{1,\infty}$$ W 1 , ∞ approach to shape optimisation with Lipschitz domains, 2021), where this idea is proposed. Our approach is demonstrated for shape optimization related to drag-minimal free floating bodies. The method is validated against existing approaches with respect to convergence of the optimization algorithm, the obtained shape, and regarding the quality of the computational grid after large deformations. Our numerical results strongly indicate that shape optimization related to the $$W^{1,\infty }$$ W 1 , ∞ -topology—though numerically more demanding—seems to be superior over the classical approaches invoking Hilbert space methods, concerning the convergence, the obtained shapes and the mesh quality after large deformations, in particular when the optimal shape features sharp corners.

Keel Design for Low Viscous Drag

1987 ◽  
Author(s):  
Clifford J. Obara ◽  
C. P. van Dam
Keyword(s):  
Boundary Layer ◽  
Laminar Flow ◽  
Laminar Boundary Layer ◽  
Leading Edge ◽  
Boundary Layer Transition ◽  
Viscous Drag ◽  
Hydrodynamic Characteristics ◽  
Sweep Angle ◽  
Layer Transition ◽  
Layer Flow

In this paper, foil and planform parameters which govern the level of viscous drag produced by the keel of a sailing yacht are discussed. It is shown that the application of laminar boundary-Layer flow offers great potential for increased boat speed resulting from the reduction in viscous drag. Three foil shapes have been designed and it is shown that their hydro­dynamic characteristics are very much dependent on location and mode of boundary-Layer transition. The planform parameter which strongly affects the capabilities of the keel to achieve laminar flow is lea ding-edge sweep angle. The two significant phenomena related to keel sweep angle which can cause premature transition of the laminar boundary layer are crossflow instability and turbulent contamination of the leading-edge attachment line. These flow phenomena and methods to control them are discussed in detail. The remaining factors that affect the maintainability of laminar flow include surface roughness, surface waviness, and freestream turbulence. Recommended limits for these factors are given to insure achievability of laminar flow on the keel. In addition, the application of a simple trailing-edge flap to improve the hydrodynamic characteristics of a foil at moderate-to-high leeway angles is studied.

Experimental Investigation on the Annular Sector Cascade of a High Endwall-Angle Turbine

2016 ◽  
Author(s):  
Weiliang Fu ◽  
Jie Gao ◽  
Chen Liang ◽  
Fukai Wang ◽  
Qun Zheng ◽  
...  
Keyword(s):  
Mach Number ◽  
Static Pressure ◽  
Incidence Angle ◽  
Pressure Sensors ◽  
Leading Edge ◽  
Control Program ◽  
Turbine Cascade ◽  
Cascade Flow ◽  
Annular Sector ◽  
The Way

The flow in high endwall-angle turbine is complex, and it is different from the ordinary turbine flow in characteristics. In order to study the flow field characteristics of high endwall-angle turbines, the annular sector cascade experimental study of high endwall-angle turbines is carried out. The blade is studied experimentally in the form of annular sector cascade. The cascade includes 7 blades, and makes up 6 flow passages, in order to simulate full cascade flow. The experimental Mach number is adjusted by the way of changing inlet total pressure, and the Mach number influence (0.7, 0.8 and 0.9) on annular sector cascade flow is studied. Based on it, the inlet incidence angle (−15°, −7.5°, 0°, 7.5° and 15° )is changed with the way of changing sector straight pipes upstream of the cascade, and its influence on turbine flow fields is studied at the Mach number of 0.8. Here, five-hole probes are used to measure aerodynamic parameters distributions downstream of the cascade, and static pressure taps are positioned on the blade surface to measure surface static pressure distribution. The auto-traversing system and pressure sensors were operated by a self-compiled program based control program. The results indicate that there are two passage vortices inside the turbine cascade flow passage under the high Mach number condition, and the passage vortex near the high endwall-angle region is bigger. As Mach number increases, the passage vortices inside turbine cascade passage will become strong, and moves towards the blade mid-span. Besides, it is shown that the way of changing sector straight pipes can achieve the variation of inlet incidence angles. And, the blade profile with big leading-edge radius has good design and off-design performance. Detailed results and analyses are presented in the paper.

scholarly journals Aerodynamic characteristics of detachable fairing shells in a subsonic incompressible flow

2019 ◽  
Author(s):  
Yu.V. Grebeneva ◽  
A.Yu. Lutsenko ◽  
A.V. Nazarova
Keyword(s):  
Flow Simulation ◽  
Aerodynamic Characteristics ◽  
Simulation Software ◽  
Stream Velocity ◽  
Normal Forces ◽  
Pitch Moment ◽  
Lift Off ◽  
Windward Surface ◽  
Aerodynamic Quality

The purpose of the work was to mathematically simulate the flow around the fairing shell of the launch vehicle at a low subsonic free-stream velocity in the α = 0...360° angle-of-attack range. The calculations were performed using the SolidWorks Flow Simulation software package and the open source OpenFoam package based on the use of numerical methods for simulating the motion of liquid and gas. Within the research, we obtained the flow patterns and the aerodynamic coefficients of the longitudinal and normal forces, the pitch moment, and calculated the aerodynamic quality of the shell. Furthermore, we determined the positions of the stable equilibrium of the model and revealed the features of the flowing around the shell of the combined form at flow from the convex and concave sides. Next, we analyzed the leeward lift-off zones and the zones with increased pressure on the windward surface during flow from the concave side. Finally, we compared the obtained characteristics with the experimental data of TsAGI.

scholarly journals Data Quality: A Negotiator between Paper-based and Digital Records in the Pakistan’s TB Control Program

2018 ◽  
Author(s):  
Syed Mustafa Ali ◽  
Farah Naureen ◽  
Arif Noor ◽  
Maged Kamel N. Boulos ◽  
Javariya Aamir ◽  
...  
Keyword(s):  
Data Quality ◽  
Quality Assessment ◽  
Control Program ◽  
Digital Data ◽  
Patient Treatment ◽  
Assessment Framework ◽  
Healthcare Organizations ◽  
Data Quality Assessment ◽  
Quality Issues

Background Increasingly, healthcare organizations are using technology for the efficient management of data. The aim of this study was to compare the data quality of digital records with the quality of the corresponding paper-based records by using data quality assessment framework. Methodology We conducted a desk review of paper-based and digital records over the study duration from April 2016 to July 2016 at six enrolled TB clinics. We input all data fields of the patient treatment (TB01) card into a spreadsheet-based template to undertake a field-to-field comparison of the shared fields between TB01 and digital data. Findings A total of 117 TB01 cards were prepared at six enrolled sites, whereas just 50% of the records (n=59; 59 out of 117 TB01 cards) were digitized. There were 1,239 comparable data fields, out of which 65% (n=803) were correctly matched between paper based and digital records. However, 35% of the data fields (n=436) had anomalies, either in paper-based records or in digital records. 1.9 data quality issues were calculated per digital patient record, whereas it was 2.1 issues per record for paper-based record. Based on the analysis of valid data quality issues, it was found that there were more data quality issues in paper-based records (n=123) than in digital records (n=110). Conclusion There were fewer data quality issues in digital records as compared to the corresponding paper-based records. Greater use of mobile data capture and continued use of the data quality assessment framework can deliver more meaningful information for decision making.

scholarly journals Fin sweep angle does not determine flapping propulsive performance

2020 ◽  
Author(s):  
Andhini N. Zurman-Nasution ◽  
Bharathram Ganapathisubramani ◽  
Gabriel D. Weymouth
Keyword(s):  
Correlation Coefficient ◽  
Large Range ◽  
Three Dimensional ◽  
Leading Edge ◽  
Potential Sweep ◽  
Sweep Angle ◽  
Propulsive Performance ◽  
Maximum Angle ◽  
And Robotics ◽  
Three Dimensional Simulations

The importance of the leading-edge sweep angle of propulsive surfaces used by unsteady swimming and flying animals has been an issue of debate for many years, spurring studies in biology, engineering, and robotics with mixed conclusions. In this work we provide results from an extensive set of three-dimensional simulations of finite foils undergoing tail-like (pitch-heave) and flipper-like (twist-roll) kinematics for a range of sweep angles while carefully controlling all other parameters. No significant change in force and power is observed for tail-like motions as the sweep angle increases, with a corresponding efficiency drop of only ≈ 2%. Similar findings are seen in flipper-like motion and the overall correlation coefficient between sweep angle and propulsive performance is 0.1-6.7%. This leads to a conclusion that fish tails or mammal flukes can have a large range of potential sweep angles without significant negative propulsive impact. A similar conclusion applies to flippers; although there is a slight benefit to avoid large sweep angles for flippers, this could be easily compensated by adjusting other hydrodynamics parameters such as flapping frequency, amplitude and maximum angle of attack to gain higher thrust and efficiency.

Excitation Of Localized Wave Packet In 3d Supersonic Boundary Layer

2017 ◽  
Vol 12 (1) ◽  
pp. 57-65
Author(s):  
Alex Yatskih ◽  
Marina Rumenskikh ◽  
Yuri Yermolaev ◽  
Aleksandr Kosinov ◽  
Nikolay Semionov ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Wave Packet ◽  
Wave Packets ◽  
Leading Edge ◽  
Supersonic Boundary Layer ◽  
Swept Wing ◽  
Sweep Angle ◽  
Asymmetric Shape ◽  
Pulse Electric ◽  
Pulse Electric Discharge

The results of experimental study of excitation of localized in time and space controlled disturbances (wave packets) in a supersonic swept-wing boundary layer are presented. The experiments were performed at Mach number M = 2 on the model of wing with a lenticular profile and a 40 degrees sweep angle of the leading edge at zero angle of attack. Wave packets were generated by a pulse electric discharge on the surface of the model. A structure of controlled wave packet was studied. It was found that the wave packet has an asymmetric shape. Comparison with the case of twodimensional boundary layer was done.

scholarly journals Vigor tests in assessing the quality of signal grass seeds

2017 ◽  
Vol 38 (6) ◽  
pp. 3491
Author(s):  
Paulo Alexandre Fernandes Rodrigues de Melo ◽  
Tatiane Sanches Jeromini ◽  
Carlos Eduardo Affonso ◽  
Edna Ursulino Alves ◽  
Cibele Chalita Martins
Keyword(s):  
Germination Rate ◽  
Pearson Correlation ◽  
Seedling Emergence ◽  
Control Program ◽  
Brachiaria Brizantha ◽  
Quality Control Program ◽  
Market Requirements ◽  
Physiological Quality ◽  
Germination Vigor

The correct assessment of the physiological quality of seed lots is necessary for the quality control program of companies. For such purpose, tests that detect differences in the physiological potential of seed lots and that meet the minimum market requirements. Thus, the study was conducted towards assessing the efficiency of laboratory tests in differentiating the quality of Brachiaria brizantha cv. Xaraés seed lots. Seeds from nine lots were assessed regarding water content, germination, first germination count, electrical conductivity and seedling emergence in sand in the laboratory (normal seedlings, first count and germination rate index), and the results were compared with those from the seedling emergence test conducted in the field. The experimental design used was completely randomized, with four replicates, and the Pearson correlation coefficient between the values from the germination, vigor and field seedling emergence tests was determined. The germination and seedling emergence in sand tests and the seedling emergence rate index efficiently assess the physiological quality of Brachiaria brizantha cv. Xaraés seed lots, providing data similar to those from seedling emergence in the field.

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