Artículos de revistas: "Variable Camber Airfoil"

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Raheem, Mohammed Abdul, Prasetyo Edi, Amjad A. Pasha, Mustafa M. Rahman y Khalid A. Juhany. "Numerical Study of Variable Camber Continuous Trailing Edge Flap at Off-Design Conditions". Energies 12, n.º 16 (20 de agosto de 2019): 3185. http://dx.doi.org/10.3390/en12163185.

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Numerical simulations are performed to study the outboard airfoil of advanced technology regional aircraft (ATRA) wings with five different variable camber continuous trailing edge flap (VCCTEF) configurations. The computational study aims to improve the aerodynamic efficiency of the airfoil under cruise conditions. The design of outboard airfoil complies with the hybrid laminar flow control design criteria. This work is unique in terms of analysis of the effects of VCCTEF on the ATRA wing’s outboard airfoil during the off-design condition. The Reynolds–Averaged Navier–Stokes equations coupled with the Spalart-Allmaras turbulence model are employed to perform the simulations for the baseline case and VCCTEF configurations. The current computational study is performed at an altitude of 10 km with a cruise Mach number of 0.77 and a Reynolds number of 2.16 × 107. Amongst all five configurations of VCCTEF airfoils studied, a flap having a parabolic profile (VCCTEF 123) configuration shows the maximum airfoil efficiency and resulted in an increase of 6.3% as compared to the baseline airfoil.

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2

Mesarič, Mihael y Franc Kosel. "Unsteady airload of an airfoil with variable camber". Aerospace Science and Technology 8, n.º 3 (abril de 2004): 167–74. http://dx.doi.org/10.1016/j.ast.2003.10.007.

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3

Yokozeki, Tomohiro, Aya Sugiura y Yoshiyasu Hirano. "Development of Variable Camber Morphing Airfoil Using Corrugated Structure". Journal of Aircraft 51, n.º 3 (mayo de 2014): 1023–29. http://dx.doi.org/10.2514/1.c032573.

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4

Bilgen, Onur, Kevin B. Kochersberger, Daniel J. Inman y Osgar J. Ohanian. "Novel, Bidirectional, Variable-Camber Airfoil via Macro-Fiber Composite Actuators". Journal of Aircraft 47, n.º 1 (enero de 2010): 303–14. http://dx.doi.org/10.2514/1.45452.

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5

Yang, Wen-Chao, Hui Wang, Jian-Ting Yang y Ji-Ming Yang. "Characterization of the Flow Separation of a Variable Camber Airfoil". Chinese Physics Letters 29, n.º 4 (abril de 2012): 044701. http://dx.doi.org/10.1088/0256-307x/29/4/044701.

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6

Li, Xingxing y Ke Yang. "Parametric exploration on the airfoil design space by numerical design of experiment methodology and multiple regression model". Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 234, n.º 1 (17 de mayo de 2019): 3–18. http://dx.doi.org/10.1177/0957650919850426.

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Robust airfoil design is crucial to efficient, stable, and safe operation for modern wind turbines. However, even for deterministic wind turbine airfoil design, the problem is complex regarding to aerodynamic, acoustic, and structural requirements of wind turbine blades. Therefore, this study aims to assess the design variable impact, identify significant variables, and obtain the correlation with the airfoil responses, to reduce the cost of the airfoil robust optimization. In this paper, the optimal hypercube design method was applied to an airfoil designed by the National Advisory Committee for Aeronautics, NACA 63-421, which is commonly employed in the outboard modern wind turbine blade, to perform the numerical design of experiments. Then, a parametric exploration on the characteristics of airfoil design space by the multiple regression model and statistical analysis method were conducted. It was identified that in regular design space, the variations of aerodynamic and structural parameters are dominated by the airfoil camber and radius of leading edge. Meanwhile, the chord-wise position of the maximum thickness also has strong impacts on the airfoil performance. In further, the overall design spaces are explored to be highly nonlinear in aerodynamic and acoustic responses because of the nonlinear effects of the airfoil chord-wise position of the maximum camber and radius of leading edge. Strong but undesirable correlations were demonstrated between the maximum lift-to-drag ratio and the total sound pressure level. These findings could serve as a valuable guidance for wind turbine airfoil robust design to screen the stochastic design variables, simplify the design space, and reduce the cost.

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7

Ang, Haisong y Hongda Li. "Preliminary airfoil design of an innovative adaptive variable camber compliant wing". Journal of Vibroengineering 18, n.º 3 (15 de mayo de 2016): 1861–73. http://dx.doi.org/10.21595/jve.2016.16705.

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8

NIU, Wei, Yufei ZHANG, Haixin CHEN y Miao ZHANG. "Numerical study of a supercritical airfoil/wing with variable-camber technology". Chinese Journal of Aeronautics 33, n.º 7 (julio de 2020): 1850–66. http://dx.doi.org/10.1016/j.cja.2020.01.008.

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9

Bilgen, Onur, Carlos De Marqui, Kevin B. Kochersberger y Daniel J. Inman. "Macro-Fiber Composite Actuators for Flow Control of a Variable Camber Airfoil". Journal of Intelligent Material Systems and Structures 22, n.º 1 (21 de diciembre de 2010): 81–91. http://dx.doi.org/10.1177/1045389x10392613.

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10

Zhao, Anmin, Zou Hui, Haichuan Jin y Dongsheng Wen. "Analysis on the Aerodynamic Characteristics of a Continuous Whole Variable Camber Airfoil". Journal of Physics: Conference Series 1215 (mayo de 2019): 012005. http://dx.doi.org/10.1088/1742-6596/1215/1/012005.

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11

Zhu, Jianyang, Lin Jiang, Hui Zhao, Bo Tao y Bin Lei. "Numerical study of a variable camber plunge airfoil under wind gust condition". Journal of Mechanical Science and Technology 29, n.º 11 (noviembre de 2015): 4681–90. http://dx.doi.org/10.1007/s12206-015-1015-z.

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12

Zhou, Wangyi, Junqiang Bai, Lei Qiao, Yasong Qiu, Rui Liu y Guangchen Shen. "A Study of Multi-Objective Aerodynamic Optimization Design for Variable Camber Airfoils and High Lift Devices". Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University 36, n.º 1 (febrero de 2018): 83–90. http://dx.doi.org/10.1051/jnwpu/20183610083.

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Aiming at the synthetical optimization of the aerodynamic performance between the low-speed condition of two-dimensional high lift devices during take-off and landing phase and the high-speed condition of variable camber airfoil during cruise phase, an aerodynamic optimization design method for high lift device based on Kriging based surrogate model and multi-objective genetic algorithm has been developed. With the application of Adaptive Dropped Hinge Flap mechanism, the low-speed take-off and landing performance and high-speed cruise performance of the aircraft is improved by coupling deflection of the flap and spoiler. The position of flap hinge, deflection angle of spoiler and deflection angle of flap are taken as design variables; The Navier-Stokes equations are used to predict the aerodynamic forces of initial samples; The Kriging based surrogate model is employed to establish the algebraic relation between design variables and aerodynamic forces at take off, landing and cruise, obtaining four efficient prediction models for aerodynamic forces; Multi-objective optimization design with multi-objective genetic algorithm is conducted on the basis of surrogate models. The automatic generation of computational grid is achieved by the mesh deformation method based on RBF (Radial Basis Function) when the design variables change. On the basis of efficient global multi-objective optimization design platform, the synthetical optimization of high-speed and low-speed aerodynamic performance is conducted; The multi-objective solution set of the Pareto frontier is verified and analyzed, and the optimal solution with well matched high and low speed performance is selected.

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13

Shi, Xing, Xianwen Huang, Yao Zheng y Susu Zhao. "Effects of cambers on gliding and hovering performance of corrugated dragonfly airfoils". International Journal of Numerical Methods for Heat & Fluid Flow 26, n.º 3/4 (3 de mayo de 2016): 1092–120. http://dx.doi.org/10.1108/hff-10-2015-0414.

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Purpose – The purpose of this paper is to explore the effects of the camber on gliding and hovering performance of two-dimensional corrugated airfoils. While the flying mechanism of natural flyers remains a myth up to nowadays, the simulation serves as a minor step toward understanding the steady and unsteady aerodynamics of the dragonfly flight. Design/methodology/approach – The lattice Boltzmann method is used to simulate the flow past the cambered corrugated dragonfly airfoil at low Reynolds numbers. For gliding flight, the maximum camber, the distance of the location of maximum camber point from the leading edge and Reynolds number are regarded as control variables; for hovering flight, the maximum camber, the flapping amplitude and trajectory are considered as control variables. Then corresponding simulations are performed to evaluate the implications of these factors. Findings – Greater gliding ratio can be reached by increasing the maximum camber of the dragonfly wing section. When the location of the maximum camber moves backward along the wing chord, large scale flow separation can be delayed. These two effects result in better gliding performances. For hovering performances, it is found that for different flapping amplitudes along an inclined plane, the horizontal force exerted on the airfoils increases with the camber, and the drag growths first but then drops. It is also found that the elliptic flapping trajectory is most sensitive to the camber of the cambered corrugated dragonfly wing section. Originality/value – The effects of the camber on gliding and hovering performance of the cambered dragonfly wing section are explored in detail. The data obtained can be helpful when designing micro aerial vehicles.

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14

Smith, L. H. "M. J. Hartmann Memorial Session Paper: NASA/GE Fan and Compressor Research Accomplishments". Journal of Turbomachinery 116, n.º 4 (1 de octubre de 1994): 555–69. http://dx.doi.org/10.1115/1.2929445.

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Fan and compressor research projects carried out at GE Aircraft Engines under NASA sponsorship are described in this paper. Four 1400-fps-tip-speed rotors designed with different airfoil shapes were found to have comparable stall lines but different efficiency trends. A stator placed behind one of these affected its performance somewhat. Adjustments of variable camber inlet guide vanes placed ahead of a 1500fps stage were found to affect its pumping capability without much affecting its stall line. For the Quiet Engine Program (QEP), two 1160-fps fans and one 1550-fps fan were tested. Development of the high-speed fan revealed the effects on performance of airfoil shape and part-span shroud blockage. The 950-fps variable-pitch fan for the Quiet Clean Short-haul Experimental Engine (QCSEE) demonstrated reverse thrust capabilities and a novel method of avoiding large core inlet pressure losses during reverse thrust operation. The 1350-fps Energy Efficient Engine (E3) fan demonstrated excellent performance with a novel quarter-stage arrangement that eliminated the need for interspool bleed while giving good dirt removal potential. The E3 compressor program employed Low Speed Research Compressor tests to identify the most appropriate blading type. High-speed rig tests and engine tests were then used to develop this 23:1-spool-pressure-ratio compressor. Research on casing boundary layer control through bleeding and blowing led to the discovery that irregular casing geometries usually give stall line enhancements even without auxiliary air circuits. Some of the resulting casing treatment research is reported herein. Instances in which NASA-sponsored research has affected GE Aircraft Engine products are pointed out.

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15

Liao, Yan Ping, Li Liu y Teng Long. "Investigation of Various Parametric Geometry Representation Methods for Airfoils". Applied Mechanics and Materials 110-116 (octubre de 2011): 3040–46. http://dx.doi.org/10.4028/www.scientific.net/amm.110-116.3040.

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Abstract—This paper presents the investigation of typical parametric geometry representation methods for airfoils, namely, PARSEC method, orthogonal basis function method and CST method. The investigation assesses the fitting accuracy of these parametric methods for various airfoils including the symmetric airfoil, cambered airfoil and supercritical airfoil. The design variables of these parametric methods are solved by the methods of least squares fit. The fitting results show that the fitting accuracy of CST method is better than other parametric methods for airfoil. The aerodynamics analysis models of these typical parametric geometry representation methods for airfoil are constructed. The pressure distributions calculated for different parametric methods are compared with the corresponding experimental pressure distributions for the actual airfoil geometry.Keywords-orthogonal basis function; PARSEC; CST; fitting accuracy; pressure distributions

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16

Raither, Wolfram, Emian Furger, Manuel Zündel, Andrea Bergamini y Paolo Ermanni. "Variable-stiffness skin concept for camber-morphing airfoils". Journal of Intelligent Material Systems and Structures 26, n.º 13 (11 de agosto de 2014): 1609–21. http://dx.doi.org/10.1177/1045389x14546780.

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17

Gandhi, Farhan y Phuriwat Anusonti-Inthra. "Skin design studies for variable camber morphing airfoils". Smart Materials and Structures 17, n.º 1 (4 de enero de 2008): 015025. http://dx.doi.org/10.1088/0964-1726/17/01/015025.

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18

Rajaram, Dushhyanth, Himanshu Akhria y S. N. Omkar. "Airfoil Topology Optimization using Teaching-Learning based Optimization". International Journal of Applied Metaheuristic Computing 6, n.º 1 (enero de 2015): 23–34. http://dx.doi.org/10.4018/ijamc.2015010102.

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This paper primarily deals with the optimization of airfoil topology using teaching-learning based optimization, a recently proposed heuristic technique, investigating performance in comparison to Genetic Algorithm and Particle Swarm Optimization. Airfoil parametrization and co-ordinate manipulations are accomplished using piecewise b-spline curves using thickness and camber for constraining the design space. The aimed objective of the exercise was easy computation, and incorporation of the scheme into the conceptual design phase of a low-reynolds number UAV for the SAE Aerodesign Competition. The 2D aerodynamic analyses and optimization routine are accomplished using the Xfoil code and MATLAB respectively. The effects of changing the number of design variables is presented. Also, the investigation shows better performance in the case of Teaching-Learning based optimization and Particle swarm optimization in comparison to Genetic Algorithm.

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19

Zhang, Qiang, Matt Goodro, Phillip M. Ligrani, Ricardo Trindade y Sri Sreekanth. "Influence of Surface Roughness on the Aerodynamic Losses of a Turbine Vane". Journal of Fluids Engineering 128, n.º 3 (16 de octubre de 2005): 568–78. http://dx.doi.org/10.1115/1.2175163.

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The effects of surface roughness on the aerodynamic performance of a turbine vane are investigated for three Mach number distributions, one of which results in transonic flow. Four turbine vanes, each with the same shape and exterior dimensions, are employed with different rough surfaces. The nonuniform, irregular, three-dimensional roughness on the tested vanes is employed to match the roughness which exists on operating turbine vanes subject to extended operating times with significant particulate deposition on the surfaces. Wake profiles are measured for two different positions downstream the vane trailing edge. The contributions of varying surface roughness to aerodynamic losses, Mach number profiles, normalized kinetic energy profiles, Integrated Aerodynamics Losses (IAL), area-averaged loss coefficients, and mass-averaged loss coefficients are quantified. Total pressure losses, Mach number deficits, and deficits of kinetic energy all increase at each profile location within the wake as the size of equivalent sandgrain roughness increases, provided the roughness on the surfaces is uniform. Corresponding Integrated Aerodynamic Loss IAL magnitudes increase either as Mach numbers along the airfoil are higher, or as the size of surface roughness increases. Data are also provided which illustrate the larger loss magnitudes which are present with flow turning and cambered airfoils, than with symmetric airfoils. Also described are wake broadening, profile asymmetry, and effects of increased turbulent diffusion, variable surface roughness, and streamwise development.

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20

Lee, Eun Seok, George S. Dulikravich y Brian H. Dennis. "Rotor Cascade Shape Optimization with Unsteady Passing Wakes Using Implicit Dual-Time Stepping and a Genetic Algorithm". International Journal of Rotating Machinery 9, n.º 5 (2003): 353–61. http://dx.doi.org/10.1155/s1023621x03000332.

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An axial turbine rotor cascade-shape optimization with unsteady passing wakes was performed to obtain an improved aerodynamic performance using an unsteady flow, Reynolds-averaged Navier-Stokes equations solver that was based on explicit, finite difference; Runge-Kutta multistage time marching; and the diagonalized alternating direction implicit scheme. The code utilized Baldwin-Lomax algebraic andk-εturbulence modeling. The full approximation storage multigrid method and preconditioning were implemented as iterative convergence-acceleration techniques. An implicit dual-time stepping method was incorporated in order to simulate the unsteady flow fields. The objective function was defined as minimization of total pressure loss and maximization of lift, while the mass flow rate was fixed during the optimization. The design variables were several geometric parameters characterizing airfoil leading edge, camber, stagger angle, and inter-row spacing. The genetic algorithm was used as an optimizer, and the penalty method was introduced for combining the constraints with the objective function. Each individual's objective function was computed simultaneously by using a 32-processor distributedmemory computer. The optimization results indicated that only minor improvements are possible in unsteady rotor/stator aerodynamics by varying these geometric parameters.

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21

Brinkerhoff, Joshua R. y Metin I. Yaras. "Numerical investigation of transition in a boundary layer subjected to favourable and adverse streamwise pressure gradients and elevated free stream turbulence". Journal of Fluid Mechanics 781 (16 de septiembre de 2015): 52–86. http://dx.doi.org/10.1017/jfm.2015.457.

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Laminar-to-turbulent transition of a boundary layer subjected to streamwise pressure gradients and elevated free stream turbulence is computed through direct numerical simulation. The streamwise pressure distribution and elevated free stream turbulence levels mimic the conditions present on the suction side of highly-cambered airfoils. Longitudinal streamwise streaks form in the laminar boundary layer through the selective inclusion of low-frequency disturbances from the free stream turbulence. The spanwise spacing normalized by local inner variables indicates stabilization of the streaks occurs by the favourable pressure gradient and prevents the development of secondary streak instability modes until downstream of the suction peak. Two distinct processes are found to trigger transition to turbulence in the adverse pressure gradient region of the flow. One involves the development of varicose secondary instability of individual low-speed streaks that results in their breakdown and the formation and growth of discrete turbulent spots. The other involves a rapid amplification of free stream disturbances in the inflectional boundary layer in the adverse pressure gradient region that results in a largely homogeneous breakdown to turbulence across the span. The effect of high-frequency free stream disturbances on the streak secondary instability and on the nonlinear processes within the growing turbulent spot are analysed through the inviscid transport of instantaneous vorticity. The results suggest that free stream turbulence contributes to the growth of the turbulent spot by generating large strain rates that activate vortex-stretching and tilting processes within the spot.

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22

"Variable camber airfoil: New concept, new challenge". Chinese Science Bulletin 57, n.º 26 (septiembre de 2012): 3532. http://dx.doi.org/10.1007/s11434-012-9917-y.

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23

Majeti, Rohin K., Berend G. van der Wall y Christoph G. Balzarek. "Linearly variable chord-extension morphing for helicopter rotor blades". CEAS Aeronautical Journal, 15 de octubre de 2020. http://dx.doi.org/10.1007/s13272-020-00477-4.

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Abstract A new morphing concept called linearly variable chord extension was studied for its effectiveness in improving the efficiency of a helicopter rotor. Apart from chord extension itself, an additional feature which is deflection of the extended part of the chord resulting in an effective camber and additional twist to the airfoil, is also studied for its effect on rotor efficiency improvement. Trim analyses were carried out for various chord-extended rotors for hover as well as various forward flight velocities using DLR’s in-house comprehensive analysis code S4. Chord extension of up to 100% and chord-extension–deflection of up to 15° were considered. Results show that the linearly variable chord-extension concept is effective in reducing power requirement in both hover and forward flight. Deflection of the extended chord also helps reduce power requirement in hover, especially at higher blade loadings. However, the root torsional moments and hence, the pitch-link loads are seen to increase substantially for the morphed rotors.

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24

Alejandro Franco, Jesus, Juan Carlos Jauregui, Andres Carbajal y Manuel Toledano-Ayala. "Shape Morphing Mechanism for Improving Wind Turbines Performance". Journal of Energy Resources Technology 139, n.º 5 (8 de junio de 2017). http://dx.doi.org/10.1115/1.4036724.

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Wind energy technology is facing new challenges due to the increment in rotor diameter. Nowadays, several studies focus on the development of new flow control methods for load alleviation, in order to increase the lifetime of the blades. This paper describes a shape morphing-based method for smart blades. The study includes an aerodynamic model with a computational search algorithm to find the optimal Cp. A section with shape morphing technology was developed to prove the performance of the method. The smart blade prototype section incorporates a novel structure with a flexible skin and a compliant mechanism. This deformable structure achieves the required displacements for different NACA profiles through camber morphing. In this way, the efficiency and the load variations are improved. The compliant mechanism has to be as light as possible and it has to be competitive in cost. In order to achieve these limitations, different actuating mechanisms were evaluated. Among different possibilities, servo actuators presented higher load/weight capabilities and the required displacement ratios to cover the entire deformable range. The airfoil is modified according to the wind condition and the wind speed is the input variable for controlling the actuators displacement. The control algorithm has a very high frequency response; in this way, the blade profile can be modified in a shorter time and it can respond to high wind velocity variations. Therefore, a deformable section improves the overall performance of wind turbines since it increases power and extends the lifetime of the blades.

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25

Beyhaghi, Saman y Ryoichi S. Amano. "Multivariable Analysis of Aerodynamic Forces on Slotted Airfoils for Wind Turbine Blades". Journal of Energy Resources Technology 141, n.º 5 (10 de abril de 2019). http://dx.doi.org/10.1115/1.4042914.

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Improvement of the aerodynamic performance for cambered airfoils with leading-edge slots is investigated in this work. This concept is proven both computationally and experimentally in recent years. Five design variables of interest are slot's length, slot's width or thickness, inlet angle, exit angle, and the vertical position. The objective is to perform design of experiment and optimization studies on these variables and evaluate the behavior of the objective functions, namely lift and lift over drag ratio (LoD), within the appropriate ranges of the independent variables. Simulations are mainly carried out at the Reynolds number of 1.6 × 106 and the angles of attack (AoA) of 6 deg for NACA 4412 airfoil. However, some of the analyses are repeated at Reynolds number of 3.2 × 106 and AoA of 0 and 8 deg to show the scalability of the results. Results indicate that the proper selection of three of the design variables, i.e., length, inlet angle, and vertical position, can have a significant impact on both lift and LoD, while the other two variables seem less influential. For the combination of the operating conditions and the values of the design variables considered in this investigation, a LoD improvement as large as 11% is observed.

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26

Sezal, Ismail, Nan Chen, Christian Aalburg, Rajesh Kumar V. Gadamsetty, Wolfgang Erhard, Alberto Scotti Del Greco, Libero Tapinassi y Matthias Lang. "Introduction of Circumferentially Nonuniform Variable Guide Vanes in the Inlet Plenum of a Centrifugal Compressor for Minimum Losses and Flow Distortion". Journal of Turbomachinery 138, n.º 9 (12 de abril de 2016). http://dx.doi.org/10.1115/1.4032884.

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In the oil and gas industry, large variations in flow rates are often encountered, which require compression trains with a wide operating range. If the stable operating range at constant speed is insufficient, variable speed drivers can be used to meet the requirements. Alternatively, variable inlet guide vanes (IGVs) can be introduced into the inlet plenum to provide pre- or counterswirl to the first-stage impeller, possibly eliminating the need for variable speed. This paper presents the development and validation of circumferentially nonuniform IGVs that were specifically designed to provide maximum angle variation at minimum losses and flow distortion for the downstream impeller. This includes the comparison of three concepts: a baseline design based on circumferentially uniform and symmetric profiles, two circumferentially nonuniform concepts based on uniquely cambered airfoils at each circumferential position, and a multi-airfoil configuration consisting of a uniquely cambered fixed part and a movable part. The idea behind the circumferentially nonuniform designs was to take into account nonsymmetric flow features inside the plenum and a bias toward large preswirl angles rather than counter-swirl during practical operation. The designs were carried out by computational fluid dynamics (CFD) and first tested in a steady, full-annulus cascade in order to quantify pressure losses and flow quality at the inlet to the impeller at different IGV setting angles (ranging from −20 deg to +60 deg) and flow rates. Subsequently, the designs were mounted in front of a typical oil and gas impeller on a high-speed rotating rig in order to determine the impact of flow distortion on the impeller performance. The results show that pressure losses in the inlet plenum could be reduced by up to 40% with the circumferentially nonuniform designs over the symmetric baseline configuration. Furthermore, a significant reduction in circumferential distortion could be achieved with the circumferentially nonuniform designs. The resulting improvement in impeller performance contributed approximately 40% to the overall efficiency gains for inlet plenum and impeller combined.

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27

He, Liu y Peng Shan. "Three-Dimensional Aerodynamic Optimization for Axial-Flow Compressors Based on the Inverse Design and the Aerodynamic Parameters". Journal of Turbomachinery 134, n.º 3 (14 de julio de 2011). http://dx.doi.org/10.1115/1.4003252.

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Integrating a genetic algorithm code with a response surface methodology code based on the artificial neural network model, this paper develops an optimization system. By introducing a quasi-three-dimensional through-flow design code and a design code of axial compressor airfoils with camber lines of arbitrary shape, and involving a three-dimensional computational fluid dynamics solver, this paper establishes a numerical aerodynamic optimization platform for the three-dimensional blades of axial compressors. The optimization in this paper mainly has four features. First, it applies the conventional inverse design method instead of the common computer aided geometric design parametrization method to generate a three-dimensional blade. Second, it chooses aerodynamic parameters with physical meaning as design variables instead of purely geometrical parameters. Third, it presents a stage-by-stage optimization strategy about the multistage turbomachinery optimization. Fourth, it introduces the visual analysis method into optimization, which can adjust variation ranges of variables by analyzing how great the variables influence the objective function. The above techniques were applied to the redesign of a single rotor row and two double-stage axial fans. The departure angles and work distributions in the inverse design were taken as design variables separately in optimizations of the single rotor and double-stage fans, and they were parametrically represented by means of Bézier curves, whose parameters were used as the optimization variables in the practical operation. The three investigated examples elucidate that not only the techniques mentioned above are appropriate and effective in engineering, but also the design guidance for similar inverse design problems can be obtained from the optimization results.

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28

Inhestern, Lukas Benjamin, James Braun, Guillermo Paniagua y José Ramón Serrano Cruz. "Design, Optimization, and Analysis of Supersonic Radial Turbines". Journal of Engineering for Gas Turbines and Power 142, n.º 3 (10 de febrero de 2020). http://dx.doi.org/10.1115/1.4044972.

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Abstract New compact engine architectures such as pressure gain combustion require ad hoc turbomachinery to ensure an adequate range of operation with high performance. A critical factor for supersonic turbines is to ensure the starting of the flow passages, which limits the flow turning and airfoil thickness. Radial outflow turbines inherently increase the cross section along the flow path, which holds great potential for high turning of supersonic flow with a low stage number and guarantees a compact design. First, the preliminary design space is described. Afterward a differential evolution multi-objective optimization with 12 geometrical design parameters is deducted. With the design tool autoblade 10.1, 768 geometries were generated and hub, shroud, and blade camber line were designed by means of Bezier curves. Outlet radius, passage height, and axial location of the outlet were design variables as well. Structured meshes with around 3.7 × 106 cells per passage were generated. Steady three-dimensional (3D) Reynolds-averaged Navier–Stokes (RANS) simulations, enclosed by the k-omega shear stress transport turbulence model were solved by the commercial solver CFD++. The geometry was optimized toward low entropy and high-power output. To prove the functionality of the new turbine concept and optimization, a full wheel unsteady RANS simulation of the optimized geometry exposed to a nozzled rotating detonation combustor (RDC) has been performed and the advantageous flow patterns of the optimization were also observed during transient operation.

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29

Kodzwa, Paul M. y John K. Eaton. "Heat Transfer Coefficient Measurements on the Film-Cooled Pressure Surface of a Transonic Airfoil". Journal of Turbomachinery 135, n.º 6 (13 de septiembre de 2013). http://dx.doi.org/10.1115/1.4023620.

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This paper presents isoenergetic temperature and steady-state film-cooled heat transfer coefficient measurements on the pressure surface of a modern, highly cambered transonic airfoil. A single passage model simulated the idealized two-dimensional flow path between blades in a modern transonic turbine. This set up offered a simpler construction than a linear cascade but produced an equivalent flow condition. Furthermore, this model allowed the use of steady-state, constant surface heat fluxes. We used wide-band thermochromic liquid crystals (TLCs) viewed through a novel miniature periscope system to perform high-accuracy (±0.2 °C) thermography. The peak Mach number along the pressure surface was 1.5, and maximum turbulence intensity was 30%. We used air and carbon dioxide as injectant to simulate the density ratios characteristic of the film cooling problem. We found significant differences between isoenergetic and recovery temperature distributions with a strongly accelerated mainstream and detached coolant jets. Our heat transfer data showed some general similarities with lower-speed data immediately downstream of injection; however, we also observed significant heat transfer attenuation far downstream at high blowing conditions. Our measurements suggested that the momentum ratio was the most appropriate variable to parameterize the effect of injectant density once jet lift-off occurred. We noted several nonintuitive results in our turbulence effect studies. First, we found that increased mainstream turbulence can be overwhelmed by the local augmentation of coolant injection. Second, we observed complex interactions between turbulence level, coolant density, and blowing rate with an accelerating mainstream.

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