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Flow Control, Active and Passive Applications
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Flow Control, Active and Passive Applications

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Energy Science and Technology".

Deadline for manuscript submissions: closed (31 December 2022) | Viewed by 26487

Printed Edition Available!
A printed edition of this Special Issue is available here.

Special Issue Editors

Dr. Josep Maria Bergadà

E-Mail Website
Guest Editor
Fluid Mechanics Department, Universitat Politècnica de Catalunya, 08034 Barcelona, Spain
Interests: active flow control; aerodynamics; compressible flow; fluid mechanics
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Gabriel Bugeda Castelltort

E-Mail Website
Guest Editor
1. Department of Civil and Environmental Engineering, Universitat Politècnica de Catalunya (UPC), 08034 Barcelona, Spain
2. International Center for Numerical Methods in Engineering (CIMNE), 08034 Barcelona, Spain
Interests: shape optimization; robust design; active flow control

Special Issue Information

Dear Colleagues,

Boundary layer modulation has drastic effects on the forces acting to any bluff body, thereby allowing large energy savings and a considerable improvement of the body efficiency. One of the latest techniques to modify the boundary layer is Active Flow Control (AFC), which mainly consists of injecting/sucking flow in particular locations where the boundary layer separation is about to occur with the aim of delaying the separation of it.

Active Flow Control (AFC) applications have just started to gain momentum and it seems that the scope of its application is likely to increase rapidly in the near future. In this Special Issue, we plan to cover all possible aspects of AFC as well as Passive Flow Control (PFC), from basic actuators configurations and performance to any sort of application on airplane airfoils, windmills, road vehicles or turbine aerodynamics, among others. Special attention will be paid to the optimization of AFC parameters in any application. Both numerical and experimental research are equally welcome in this Special Issue.

Researchers are encouraged to submit high quality and novel papers which, after being peer reviewed by specialists in the field, shall be published. 

Dr. Josep Maria Bergadà
Prof. Dr. Gabriel Bugeda Castelltort
Guest Editors

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Applied Sciences is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • active flow control
  • passive flow control
  • aerodynamics
  • optimization
  • turbulent boundary layer flow control
  • drag reduction, skin–friction drag reduction
  • plasma actuators
  • jet actuators
  • moving walls

Published Papers (15 papers)

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Editorial

Jump to: Research, Review

3 pages, 195 KiB  
Editorial
Flow Control, Active and Passive Applications
by Josep M. Bergadà and Gabriel Bugeda
Appl. Sci. 2023, 13(16), 9228; https://0-doi-org.brum.beds.ac.uk/10.3390/app13169228 - 14 Aug 2023
Viewed by 882
Abstract
The Boundary Layer (BL) dynamic performance greatly affects the forces acting on any Bluff body [...] Full article
(This article belongs to the Special Issue Flow Control, Active and Passive Applications)

Research

Jump to: Editorial, Review

14 pages, 6601 KiB  
Article
A New Flow Control Method of Slat-Grid Channel-Coupled Configuration on High-Lift Device
by Jingyi Yu and Baigang Mi
Appl. Sci. 2023, 13(6), 3488; https://0-doi-org.brum.beds.ac.uk/10.3390/app13063488 - 09 Mar 2023
Cited by 1 | Viewed by 1004
Abstract
A slot formed between the slat and the main wing of the 2D high-lift device is used to accelerate the convergence of the flow to the upper surface of the main wing to improve the flow field quality. In order to further enhance [...] Read more.
A slot formed between the slat and the main wing of the 2D high-lift device is used to accelerate the convergence of the flow to the upper surface of the main wing to improve the flow field quality. In order to further enhance flow characteristics, this paper proposes a design method for multi-channel leading-edge slats based on grid flow channels. On the one hand, a specific shape of a shrinking expansion tube is formed to improve the lift characteristics of the leading slat. On the other hand, the newly formed slot plays a similar role to that of the jet stream, delaying the separation on the upper surface of the main wing, making the separation point move back and helping to improve the lift characteristics of the main wing. The optimization of coupled slat-grid channel configuration is developed by using the DOE algorithm. The geometric parameters, such as coordinates and curve slope, are considered as design variables, and the maximum lift–drag ratio is taken as the optimization objective required to obtain the optimal configuration. The simulation and optimization results show that the lift coefficient increases by 3.3%, the drag coefficient decreases by 12.7%, and the lift–drag ratio increases by 18.4% of the optimal configuration compared with the original airfoil at an angle of attack of 16.3°. Full article
(This article belongs to the Special Issue Flow Control, Active and Passive Applications)
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25 pages, 14307 KiB  
Article
Toward the Utilization of 3D Blading in the Cantilevered Stator from Highly Loaded Compressors
by Xiaobin Xu, Ruoyu Wang, Xianjun Yu, Guangfeng An, Ying Qiu and Baojie Liu
Appl. Sci. 2023, 13(5), 3335; https://0-doi-org.brum.beds.ac.uk/10.3390/app13053335 - 06 Mar 2023
Cited by 1 | Viewed by 1147
Abstract
Three-dimensional blading is an efficient technique in compressor aerodynamic design, and its function mechanism in the cantilevered stator needs to be addressed. This paper focuses on the sweep and dihedral in the cantilevered stator and seeks to expose their effects through detailed flow [...] Read more.
Three-dimensional blading is an efficient technique in compressor aerodynamic design, and its function mechanism in the cantilevered stator needs to be addressed. This paper focuses on the sweep and dihedral in the cantilevered stator and seeks to expose their effects through detailed flow field analysis. Results show that the forward sweep could alleviate the corner flow separation by preventing the accumulation of the secondary flow toward the corner region, resulting in stronger flow separation at the blade trailing edge; in summary, forward sweep with appropriate parameters could increase static pressure rise by 14.3%. The positive dihedral will carry the endwall flow to the upper-span sections, thereby reducing blade corner separation; hence, as much as 23.5% improvement in static pressure rise could be obtained with the appropriate dihedral. Moreover, the combination of a relatively large sweep height and a moderate sweep angle with a low dihedral height and a moderate sweep angle provides optimum aerodynamic performance; the static pressure rise coefficient sees an increment of 25.5% at the near stall point. An experiment is then performed to further validate the theory, which shows a 2% improvement in efficiency of 3D blading at small mass flow rates. However, the secondary leakage should be given attention at high mass flow coefficients, while the corner separation needs further elimination at small mass flow rates. Full article
(This article belongs to the Special Issue Flow Control, Active and Passive Applications)
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24 pages, 15858 KiB  
Article
Unsteady Aerodynamic Design of a Flapping Wing Combined with a Bionic Wavy Leading Edge
by Xuan Bai, Hao Zhan and Baigang Mi
Appl. Sci. 2023, 13(3), 1519; https://0-doi-org.brum.beds.ac.uk/10.3390/app13031519 - 24 Jan 2023
Cited by 1 | Viewed by 1820
Abstract
Based on the bionic design of the humpback whale fin, a passive flow control method is proposed to obtain greater flapping lift by applying the wavy leading edge structure to the straight symmetrical flapping wing. The leading edge of the conventional flapping wing [...] Read more.
Based on the bionic design of the humpback whale fin, a passive flow control method is proposed to obtain greater flapping lift by applying the wavy leading edge structure to the straight symmetrical flapping wing. The leading edge of the conventional flapping wing is replaced by the wavy shape represented by regular trigonometric function to form a special passive flow control configuration imitating the leading edge of the humpback whale fin. The dynamic aerodynamic performance and flow field characteristics of straight wing and wavy leading edge flapping wing with different parameters are compared and analyzed by CFD numerical simulation. The simulation results show that the wavy leading edge structure changes the flow field of the baseline flapping wing and reduces the pressure on the upper surface of the flapping wing during the process of downward flapping, thereby increasing the pressure difference between the upper and lower surfaces of the flapping wing and increasing the lift. The sensitivity analysis of the design parameters shows that in order to obtain the maximum lift coefficient while losing the least thrust, the smaller amplitude should be selected on the premise of selecting the smaller wavelength. Among the configurations of different design parameters calculated in this paper, the optimal wavy leading edge flapping wing configuration increases the time average lift coefficient by 32.86% and decreases the time average thrust coefficient by 14.28%. Compared with the straight wing, it has better low-speed flight and can withstand greater take-off weight. Full article
(This article belongs to the Special Issue Flow Control, Active and Passive Applications)
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18 pages, 6089 KiB  
Article
Internal Aerodynamic Performance Enhancement for Aircraft with High Maneuver by Designing a Distributed Submerged Inlet
by Junyao Zhang and Baigang Mi
Appl. Sci. 2023, 13(3), 1459; https://0-doi-org.brum.beds.ac.uk/10.3390/app13031459 - 22 Jan 2023
Cited by 2 | Viewed by 1481
Abstract
Submerged inlet has been widely used in UAVs and cruise missiles due to its good stealth characteristics, but it also brings the disadvantage of poor aerodynamic characteristics. Especially in large maneuvering flight, the flow field near the fuselage has a strong unsteady effect, [...] Read more.
Submerged inlet has been widely used in UAVs and cruise missiles due to its good stealth characteristics, but it also brings the disadvantage of poor aerodynamic characteristics. Especially in large maneuvering flight, the flow field near the fuselage has a strong unsteady effect, and the total pressure recovery coefficient and distortion characteristics have deteriorated sharply. In order to investigate the steady and transient aerodynamic characteristics of the submerged inlet in large maneuver flight and improve its maneuver envelope, a design scheme of a distributed submerged inlet for large maneuver flight is proposed in this paper. Taking a cruise missile as the research object, the steady and transient analysis of the conventional submerged inlet and the distributed submerged inlet is carried out using CFD numerical method. The results show that the distributed submerged inlet can significantly improve the inlet performance and enhance the sideslip limit of the submerged inlet during large sideslip maneuver flight. When the sideslip angle is 30°, compared with the conventional submerged inlet configuration, the outlet total pressure recovery coefficient of the distributed submerged inlet configuration is increased by 44.2%, and the total pressure distortion index is reduced by 66.3%. Full article
(This article belongs to the Special Issue Flow Control, Active and Passive Applications)
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18 pages, 3173 KiB  
Article
Drag Reduction Analysis of the Hydrostatic Bearing with Surface Micro Textures
by Youyun Shang, Kai Cheng, Qingshun Bai and Shijin Chen
Appl. Sci. 2022, 12(21), 10831; https://0-doi-org.brum.beds.ac.uk/10.3390/app122110831 - 26 Oct 2022
Cited by 5 | Viewed by 1330
Abstract
Surface microtexturing has been widely used due to its good hydrophobic or drag reduction characteristics, and become an effective method to improve product performance and reduce energy consumption. This paper mainly discusses the improvement of microtextures on the dynamic pressure characteristics of hydrostatic [...] Read more.
Surface microtexturing has been widely used due to its good hydrophobic or drag reduction characteristics, and become an effective method to improve product performance and reduce energy consumption. This paper mainly discusses the improvement of microtextures on the dynamic pressure characteristics of hydrostatic bearings, and explores the effects of texture parameters on carrying capacity, macroscopic wall two-plane shear force, cavity area and other factors. In the oil film model calculation of the smooth wall surface of the radial hydrostatic bearing under the action of high speed and large external load, the oil film divergent wedge often has a negative pressure area, which is obviously not in line with the actual situation, so the cavitation effect needs to be considered. The CFD analysis method of the “gas-oil” two-phase flow model was carried out by using the mixture model to seek the optimal texture model scheme and thus to improve the load carrying capacity (LCC) and reduce the wall shear force. The effects of the texture area arrangement and geometric parameters on the lubrication characteristics were compared and analyzed. It is found that the carrying capacity of local texture is better than that of global texture, and different texture arrangements can achieve better drag reduction rates. The work presented in this paper studies the lubrication of the surface texture of a hydrostatic bearing. Taking the oil film carrying capacity and shear force as the target parameters, the factors, such as texture morphology, geometric parameters, texture distribution and cavitation phenomenon, are investigated through simulation and experimental methods. The surface textured hydrostatic bearing is expected to obtain the maximum oil film carrying capacity and the minimum friction resistance. The analysis results show that by arranging the partial streamwise texture at the rear end of the diverging wedge, the maximum shear force of the wall can be reduced by about 15%, and the LCC can be increased by about 18%. Full article
(This article belongs to the Special Issue Flow Control, Active and Passive Applications)
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21 pages, 8150 KiB  
Article
Computational Study of the Plasma Actuator Flow Control for an Airfoil at Pre-Stall Angles of Attack
by Takuto Ogawa, Kengo Asada, Makoto Sato, Tomoaki Tatsukawa and Kozo Fujii
Appl. Sci. 2022, 12(18), 9073; https://0-doi-org.brum.beds.ac.uk/10.3390/app12189073 - 09 Sep 2022
Cited by 3 | Viewed by 1570
Abstract
Large-eddy simulations of the flows over an NACA0015 airfoil were conducted to investigate a flow control authority of a dielectric barrier discharge plasma actuator at pre-stall angles of attack. The Reynolds number was set to 63,000, and angles of attack were set to [...] Read more.
Large-eddy simulations of the flows over an NACA0015 airfoil were conducted to investigate a flow control authority of a dielectric barrier discharge plasma actuator at pre-stall angles of attack. The Reynolds number was set to 63,000, and angles of attack were set to 4, 6, 8, and 10 degrees. The plasma actuator was installed at 5% chord length from the airfoil’s leading edge. Good flow control authority was confirmed in terms of lift-to-drag ratio increase and drag reduction. These improvements mainly result from the reduction of the pressure drug, which is due to the change in pressure distribution accompanying the movement and shrink of the laminar separation bubble on the airfoil surface. Additionally, although flow control using a burst drive with a nondimensional burst frequency of six improves the lift-to-drag ratio at all angles of attack, the phenomena leading to the improvement differ between near-stall angles (10 and 12 degrees) and the other lower angles. At near-stall angles, the turbulent transition is rapidly promoted by PA, and the flow is reattached. Whereas, at the lower angles, the transport of two-dimensional vortex structures, which maintain their structures up to downstream and suppress the turbulent transition, makes the flow reattachment. Full article
(This article belongs to the Special Issue Flow Control, Active and Passive Applications)
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12 pages, 11774 KiB  
Article
Efficiency of Pulsating Base Bleeding to Control Trailing Edge Flow Configurations
by Carlos Carbajosa, Alejandro Martinez-Cava, Eusebio Valero and Guillermo Paniagua
Appl. Sci. 2022, 12(13), 6760; https://0-doi-org.brum.beds.ac.uk/10.3390/app12136760 - 04 Jul 2022
Cited by 2 | Viewed by 1660
Abstract
As high-pressure-turbines operate at extreme temperature conditions, base bleed can be applied at the trailing edge of the airfoils, enhancing the thermal protection along the trailing edge surface, but also disrupting the trailing edge flow and altering the overall aerodynamic pressure losses. The [...] Read more.
As high-pressure-turbines operate at extreme temperature conditions, base bleed can be applied at the trailing edge of the airfoils, enhancing the thermal protection along the trailing edge surface, but also disrupting the trailing edge flow and altering the overall aerodynamic pressure losses. The current work explores the potential use of base bleed as a flow control tool to modulate the flow between turbine blade rows. Through the numerical analysis of a symmetric airfoil immersed in a subsonic flow, the effects that trailing edge ejection has on the base region properties and the downstream flow are evaluated. In particular, previous research constrained to steady blowing is now extended to consider an unsteady pulsating base bleed injection. Three injection frequencies are investigated, covering a wide range of base bleed intensities. The results presented herein demonstrate that pulsating bleed flow is more efficient than its steady counterpart in terms of reducing pressure losses and controlling the primary frequency of the downstream oscillations for the same mass flow injection. Full article
(This article belongs to the Special Issue Flow Control, Active and Passive Applications)
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20 pages, 9339 KiB  
Article
Influence of Wake Intensity on the Unsteady Flow Characteristics of the Integrated Aggressive Interturbine Duct
by Zhijun Lei, Hongrui Liu, Gang Li, Jianbo Gong, Yanfeng Zhang, Xingen Lu, Gang Xu and Junqiang Zhu
Appl. Sci. 2022, 12(13), 6655; https://0-doi-org.brum.beds.ac.uk/10.3390/app12136655 - 30 Jun 2022
Cited by 4 | Viewed by 1144
Abstract
The interturbine transition duct (ITD), located between the high-pressure (HP) and low-pressure (LP) turbines of aeroengines, tends to be designed as an aggressive ITD integrated with wide-chord struts to meet the requirements of civil aeroengines for high bypass ratios and thrust–weight ratios. This [...] Read more.
The interturbine transition duct (ITD), located between the high-pressure (HP) and low-pressure (LP) turbines of aeroengines, tends to be designed as an aggressive ITD integrated with wide-chord struts to meet the requirements of civil aeroengines for high bypass ratios and thrust–weight ratios. This paper presents a detailed unsteady numerical investigation of the effects of the HP rotor trailing-edge radius on the unsteady flow characteristics in the integrated aggressive interturbine transition duct (AITD), including the transport and dissipation of HP rotor wakes, the control mechanism of HP rotor wakes on flow separation and the influence of wake parameters. A sweeping rod, with a nondimensional diameter ranging from d/s = 0.056~0.143 (based on the pitch (s) of wide-chord struts at the midspan) and a reduced frequency (f) of 1.07, is used to simulate the HP rotor wake to decouple its influence from other secondary flows. Using the k-ω SST turbulence model and gamma–theta transition model, a structured grid with 6.3 million nodes can achieve similar global results. The wake in the lower part of the AITD channel dissipates rapidly because of the stretching between its own circumferential motion and the radial upward secondary flow, especially for a small d/s. Only the residual wake in the upper part can reach wide-chord struts in the case with large d/s. A sweeping rod with a large d/s can reduce the radial pressure gradient in the AITD, inhibit the internal secondary flow to a certain extent, reduce the dissipation rate of the wake, enhance its suppression effect on flow separation on a wide-chord strut, and decrease the flow loss. However, the wake can also enhance the passage vortex due to the increasing circumferential pressure gradient in the wide-chord strut channel, resulting in increasing blade profile loss. In the scope of this study, the aerodynamic gain of the wake is still not enough to compensate for its loss increment (including its own dissipation loss). Therefore, selecting a small trailing-edge radius of the HP rotor is conducive to improving the aerodynamic performance of the integrated AITD. Full article
(This article belongs to the Special Issue Flow Control, Active and Passive Applications)
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17 pages, 3343 KiB  
Article
Drag Reduction by Riblets on a Commercial UAV
by Lorenzo Cacciatori, Carlo Brignoli, Benedetto Mele, Federica Gattere, Celeste Monti and Maurizio Quadrio
Appl. Sci. 2022, 12(10), 5070; https://0-doi-org.brum.beds.ac.uk/10.3390/app12105070 - 18 May 2022
Cited by 9 | Viewed by 2948
Abstract
Riblets are micro-grooves capable of decreasing skin-friction drag, but recent work suggests that additional benefits are possible for other components of aerodynamic drag. The effect of riblets on a fixed-wing, low-speed Unmanned Aerial Vehicle (UAV) on the total aerodynamic drag are assessed here [...] Read more.
Riblets are micro-grooves capable of decreasing skin-friction drag, but recent work suggests that additional benefits are possible for other components of aerodynamic drag. The effect of riblets on a fixed-wing, low-speed Unmanned Aerial Vehicle (UAV) on the total aerodynamic drag are assessed here for the first time by means of RANS simulations. Since the microscopic scale of riblets precludes their direct representation in the geometric model of the UAV, we model riblets via a homogenised boundary condition applied on the smooth wall. The boundary condition consists in a suitably tuned partial slip, which assumes riblets to be locally aligned with the flow velocity, and to possess optimal size. Several configurations of riblets coverage are considered to extract the potential for drag reduction of different parts of the aircraft surface. Installing riblets with optimal size over the complete surface of the UAV leads to a reduction of 3% for the drag coefficient of the aircraft. In addition to friction reduction, analysis shows a significant additional form of drag reduction localised on the wing. By installing riblets only on the upper surface of the wing, total drag reduction remains at 1.7%, with a surface coverage that is only 29%, thus yielding a significant improvement in the cost–benefit ratio. Full article
(This article belongs to the Special Issue Flow Control, Active and Passive Applications)
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19 pages, 55459 KiB  
Article
Aerodynamic Efficiency Improvement on a NACA-8412 Airfoil via Active Flow Control Implementation
by Nil Couto and Josep M. Bergada
Appl. Sci. 2022, 12(9), 4269; https://0-doi-org.brum.beds.ac.uk/10.3390/app12094269 - 23 Apr 2022
Cited by 8 | Viewed by 2175
Abstract
The present paper introduces a parametric optimization of several Active Flow Control (AFC) parameters applied to a NACA-8412 airfoil at a single post-stall Angle of Attack (AoA) of 15∘ and Reynolds number Re = 68.5×103. The aim [...] Read more.
The present paper introduces a parametric optimization of several Active Flow Control (AFC) parameters applied to a NACA-8412 airfoil at a single post-stall Angle of Attack (AoA) of 15∘ and Reynolds number Re = 68.5×103. The aim is to enhance the airfoil efficiency and to maximize its lift. The boundary layer separation point was modified using Synthetic Jet Actuators (SJA), and the airfoil optimization was carried on by systematically changing the pulsating frequency, momentum coefficient and jet inclination angle. Each case has been evaluated using Computational Fluid Dynamic (CFD) simulations, being the Reynolds Averaged Navier–Stokes equations (RANS) turbulence model employed the Spalart Allmaras (SA) one. The results clarify which are the optimum AFC parameters to maximize the airfoil efficiency. It also clarifies which improvement in efficiency is to be expected under the operating working conditions. An energy balance is presented at the end of the paper, showing that for the optimum conditions studied the energy saved is higher than the one needed for the actuation. The paper clarifies how a parametric analysis has to be performed and which AFC parameters can be initially set as constant providing sufficient previous knowledge of the flow field is already known. A maximum efficiency increase versus the baseline case of around 275% is obtained from the present simulations. Full article
(This article belongs to the Special Issue Flow Control, Active and Passive Applications)
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13 pages, 2376 KiB  
Article
A New Hybrid Optimization Method, Application to a Single Objective Active Flow Control Test Case
by Martí Coma, Navid Monshi Tousi, Jordi Pons-Prats, Gabriel Bugeda and Josep M. Bergada
Appl. Sci. 2022, 12(8), 3894; https://0-doi-org.brum.beds.ac.uk/10.3390/app12083894 - 12 Apr 2022
Cited by 4 | Viewed by 1638
Abstract
Genetic Algorithms (GA) are useful optimization methods for exploration of the search space, but they usually have slowness problems to exploit and converge to the minimum. On the other hand, gradient based methods converge faster to local minimums, although are not so robust [...] Read more.
Genetic Algorithms (GA) are useful optimization methods for exploration of the search space, but they usually have slowness problems to exploit and converge to the minimum. On the other hand, gradient based methods converge faster to local minimums, although are not so robust (e.g., flat areas and discontinuities can cause problems) and they lack exploration capabilities. This article presents a hybrid optimization method trying to combine the virtues of genetic and gradient based algorithms, and to overcome their corresponding drawbacks. The performance of the Hybrid Method is compared against a gradient based method and a Genetic Algorithm, both used alone. The rate of convergence of the methods is used to compare their performance. To take into account the robustness of the methods, each one has been executed more than once, with different starting points for the gradient based method and different random seeds for the Genetic Algorithm and the Hybrid Method. The performance of the different methods is tested against an optimization Active Flow Control (AFC) problem over a 2D Selig–Donovan 7003 (SD7003) airfoil at Reynolds number 6×104 and a 14 degree angle of attack. Five design variables are considered: jet position, jet width, momentum coefficient, forcing frequency and jet inclination angle. The objective function is defined as minus the lift coefficient (−Cl), so it is defined as a minimization problem. The proposed Hybrid Method enables working with N optimization algorithms, multiple objective functions and design variables per optimization algorithm. Full article
(This article belongs to the Special Issue Flow Control, Active and Passive Applications)
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23 pages, 2776 KiB  
Article
An Efficient Hybrid Evolutionary Optimization Method Coupling Cultural Algorithm with Genetic Algorithms and Its Application to Aerodynamic Shape Design
by Xin Zhao, Zhili Tang, Fan Cao, Caicheng Zhu and Jacques Periaux
Appl. Sci. 2022, 12(7), 3482; https://0-doi-org.brum.beds.ac.uk/10.3390/app12073482 - 29 Mar 2022
Cited by 7 | Viewed by 1699
Abstract
Evolutionary algorithms have been widely used to solve complex engineering optimization problems with large search spaces and nonlinearity. Both cultural algorithm (CA) and genetic algorithms (GAs) have a broad prospect in the optimization field. The traditional CA has poor precision in solving complex [...] Read more.
Evolutionary algorithms have been widely used to solve complex engineering optimization problems with large search spaces and nonlinearity. Both cultural algorithm (CA) and genetic algorithms (GAs) have a broad prospect in the optimization field. The traditional CA has poor precision in solving complex engineering optimization problems and easily falls into local optima. An efficient hybrid evolutionary optimization method coupling CA with GAs (HCGA) is proposed in this paper. HCGA reconstructs the cultural framework, which uses three kinds of knowledge to build the belief space, and the GAs are used as an evolutionary model for the population space. In addition, a knowledge-guided t-mutation operator is developed to dynamically adjust the mutation step and introduced into the influence function. HCGA achieves a balance between exploitation and exploration through the above strategies, and thus effectively avoids falling into local optima and improves the optimization efficiency. Numerical experiments and comparisons with several benchmark functions show that the proposed HCGA significantly outperforms the other compared algorithms in terms of comprehensive performance, especially for high-dimensional problems. HCGA is further applied to aerodynamic optimization design, with the wing cruise factor being improved by 23.21%, demonstrating that HCGA is an efficient optimization algorithm with potential applications in aerodynamic optimization design. Full article
(This article belongs to the Special Issue Flow Control, Active and Passive Applications)
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19 pages, 4436 KiB  
Article
Simulation of the Influence of Wing Angle Blades on the Performance of Counter-Rotating Axial Fan
by Guijun Gao, Qingshan You, Ziming Kou, Xin Zhang and Xinqi Gao
Appl. Sci. 2022, 12(4), 1968; https://0-doi-org.brum.beds.ac.uk/10.3390/app12041968 - 14 Feb 2022
Cited by 3 | Viewed by 1978
Abstract
We took the mining counter-rotating fan FBD No.8.0 as the research object, used orthogonal test and numerical simulation to study the influence of wing angle blade on fan performance, and simulated and analyzed its aerodynamic noise. The results show that the pressure distribution [...] Read more.
We took the mining counter-rotating fan FBD No.8.0 as the research object, used orthogonal test and numerical simulation to study the influence of wing angle blade on fan performance, and simulated and analyzed its aerodynamic noise. The results show that the pressure distribution of the optimal blade angle blade fan on the pressure surface of the secondary blade is stronger than that of the prototype blade, and the maximum pressure at the blade height of 25%, 50%, and 75% is increased by 2.3%, 9.3%, and 8.1%, respectively, than original blade. Compared with the prototype blade; wing angle blades can effectively reduce the generation of shedding vortices at the trailing edge of the blade, and reduce the strength of shedding vortices, so that the entropy production of the optimal wing angle blade fan is 1.55% lower than that of the prototype fan. Compared with the prototype fan, the full pressure and efficiency of the angle blade fan under the rated flow have increased by 7.24% and 1.76%, and the average increase of 11.32% and 3.88%, respectively, under the full flow condition. Compared with the prototype fan, the maximum sound power of the wing blade fan in the first and second blade trailing edge regions is reduced by 0.17% and 1.62%, respectively. Full article
(This article belongs to the Special Issue Flow Control, Active and Passive Applications)
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Review

Jump to: Editorial, Research

18 pages, 3137 KiB  
Review
A Review of Flow Control for Gust Load Alleviation
by Yonghong Li and Ning Qin
Appl. Sci. 2022, 12(20), 10537; https://0-doi-org.brum.beds.ac.uk/10.3390/app122010537 - 19 Oct 2022
Cited by 7 | Viewed by 2530
Abstract
Effective control of aerodynamic loads, such as maneuvering load and gust load, allows for reduced structural weight and therefore greater aerodynamic efficiency. After a basic introduction in the types of gusts and the current gust load control strategies for aircraft, we outline the [...] Read more.
Effective control of aerodynamic loads, such as maneuvering load and gust load, allows for reduced structural weight and therefore greater aerodynamic efficiency. After a basic introduction in the types of gusts and the current gust load control strategies for aircraft, we outline the conventional gust load alleviation techniques using trailing-edge flaps and spoilers. As these devices also function as high-lift devices or inflight speed brakes, they are often too heavy for high-frequency activations such as control surfaces. Non-conventional active control devices via fluidic actuators have attracted some attention recently from researchers to explore more effective gust load alleviation techniques against traditional flaps for future aircraft design. Research progress of flow control using fluidic actuators, including surface jet blowing and circulation control (CC) for gust load alleviation, is reviewed in detail here. Their load control capabilities in terms of lift force modulations are outlined and compared. Also reviewed are the flow control performances of these fluidic actuators under gust conditions. Experiments and numerical efforts indicated that both CC and surface jet blowing demonstrate fast response characteristics, capable for timely adaptive gust load controls. Full article
(This article belongs to the Special Issue Flow Control, Active and Passive Applications)
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