大型客机增升装置的气动特性研究

近年来, 随着深度学习在图像处理、语音识别、自动驾驶、自然语言处理等领域迅速发展, 该技术也被越来越广泛地应用于处理具有复杂非线性、高维度、大数据量等特点的流体力学方向. 传统的方法无法有效地处理这些庞大的数据, 深度学习因其具有强大的函数拟合能力, 可以从大量的数据中挖掘有用的信息. 当前, 流体力学深度学习技术有了初步的一些研究成果, 在流动信息特征提取、多源数据信息融合及流场的智能重构等方面具有重要的工程价值, 其应用潜力逐渐得到证实. 如何利用地面风洞试验、数值模拟及飞行试验获取的数据进行深入挖掘, 快速智能感知及重构流场, 可为主动流动控制提供重要指导. 本文主要从深度学习不同类型的网络结构出发探讨了卷积神经网络在流场重构中的研究进展, 文章首先介绍卷积神经网络的一些基本概念以及基本网络结构, 之后简要介绍流场超分辨率重构网络、端到端的映射网络、长短期记忆网络的基本结构与理论, 并详细归纳出他们的改进形式在流场重构领域的一系列研究进展与成果, 最后对文章做出总结并探讨了流场重构深度学习技术所面临的挑战与展望.

… flow past the high-lift system due to changing flap riggings. At … flap parameters, one can observe the following: 1) the flap gap affects the flap suction peak significantly whereas the flap …

High-lift devices are essential aerodynamic features used to enhance aircraft performance during the low-speed regime, namely takeoff and landing, as well as in high-maneuverability flight regimes. In this paper, a comparative study of high-lift system design philosophies used in two classes of aircraft, commercial airliners and military fighters, is presented. Commercial aviation has an overriding interest in trailing-edge high-lift devices for fuel efficiency, safety, and economic maturity. Military fighter design has an overriding interest in leading-edge devices for enhanced aircraft maneuverability, controllability, and post-stall flight characteristics. The paper presents a systematic comparison of design philosophies used in high-lift system design in commercial transports and military fighters. Commercial aviation uses trailing-edge high lift devices on aircraft such as the Boeing and Airbus families for lift-to-drag ratio optimization, and to operate within acceptable margins of weight, size, and maintenance. Military fighter aircraft use trailing-edge and leading-edge devices, such as slats and Leading-Edge Vortex Controllers (LEVCONs), to achieve enhanced aircraft maneuverability, controllability, and post-stall flight characteristics. The LEVCON operation is presented, including the mechanism of vortex generation and delay of stall. The extent to which modern fighters integrate the leading-edge aerodynamic controls with digital flight control is discussed. A comparative analysis of airliner and fighter high lift system design philosophies is presented. Airliner high lift systems are designed to operate in a predictable, safe, and efficient regime of low-speed flight. Fighter high lift systems are designed to operate in a regime of extreme flight regimes, in particular high angles of attack. Finally, future trends in high lift system design are discussed including unmanned aerial vehicles (UAVs) and blended-wing-body configurations. A review of promising trends in adaptive wing geometries, smart materials, and active flow control actuators is presented, including the prospect of truly aerostructurally integrated intelligent high lift systems.

Aerodynamic performance of aircraft wings vary with flight path conditions and depend on efficiency of high lift systems. In this work, a study on high lift devices and mechanisms that aim to increase maximum lift coefficient and reduce drag on commercial aircraft wings is discussed. Typically, such extensions are provided to main airfoil along span wise direction of wing and can increase lift coefficient by more than 100% during operation. Increasing the no of trailing edge flaps in chord wise direction could result in 100% increment in lift coefficient at a given angle of attack but leading edge slats improve lift by delaying the flow separation near stall angle of attack. Different combinations of trailing edge flaps used by Airbus, Boeing and McDonnel Douglas manufacturers are explained along with kinematic mechanisms to deploy them. The surface pressure distribution for 30P30N airfoil is evaluated using 2D vortex panel method and effects of chord wise boundary layer flow transitions on aerodynamic lift generation is discussed. The results showed better agreements with experiment data for high Reynolds number (9 million) flow conditions near stall angle of attack.

… A complete procedure to study and optimize a multi-element high-lift device is presented … parameters such as the flap and slat rotations. Then, the high-lift device is optimized according …

… to airframe noise are landing gear and high-lift devices2. In the latter case, the unsteady flow in and around leading-edge slats and trailing edge flap systems is known to be responsible …

… high-lift systems for both transports and military aircraft employ both leading-edge devices (such as slats) and trailing-edge devices … high-lift wing geometries with part-span slat and flap …

… THE high-lift devices to be considered in this paper, the slat and slotted flap, have been … to produce a configuration of wing and high-lift devices which yields the optimum performance. …

… of high-lift devices and systems. These … flap to be used on the 727 jet transport in the 1960s. Further work resulted in the leading-edge slat and the era of leading-edge high-lift devices…

… In this paper, a transition prediction approach for the slat of a high-lift system is … slat and flap settings employed are slat deflection of 30 deg, slat gap of 2.95%, slat overhang of 2.5%, flap …

… high-lift system of this wing section includes the following fi ve elements: the segmented slat… Note, this Rbar value was obtained for the high-lift system in the takeoff position; ie, slat nos. …

The application of active flow control for high-lift multi-element wing sections is investigated. A computational fluid dynamics procedure is used to simulate the interactive flow in conjunction with distributed flow control. Favorable nonlinear interactions using flow control on a conventional wing section and an advanced airfoil lead to major aerodynamic performance improvements at representative takeoff and landing conditions. This study demonstrates that judicious application of flow control at select locations on the individual wing elements may lead to near inviscid lift levels in the linear lift range and substantial gains in maximum lift.

An aeroacoustic model test has been conducted to investigate the mechanisms of sound generation on high-lift wing configurations. This paper presents an analysis of flap side-edge …

… aerofoil with NACA22 leading-edge slat is experimentally and … illustrate that the leading-edge slat significantly delays the stall … with fowler flap and specially developed leadingedge slot. …

<div class="htmlview paragraph">Today, Computational Fluid Dynamics (CFD) is more commonly used in aerospace industry, and becoming an essential engineering tool. CFD is largely being used as a preliminary design tool, and often accompanied by wind tunnel test for modeling validation. Embry-Riddle Aeronautical University (ERAU), Prescott campus, one of the few universities in the U.S. to provide strong undergraduate hands-on CFD curriculum, allowed a group of students the opportunity to model flow over two different airfoils using CFD applications and also with the use of a subsonic wind tunnel for CFD validations. A NACA 23012 airfoil with a double slotted Fowler flap and a leading edge Handley-Page slat was created for the purpose of this analysis. This research effort is an example of using both structured and unstructured grid CFD to expose students at an undergraduate level and to recognize its relationship between experimental data on an aircraft wing design.</div>

… Fowler flap, plain flap, and slat are taken into consideration … affected by ground effect; Fowler flap can increase the lift for … 2 located near the leading edge of Fowler flap. High pressure …

… was applied at the leading-edge flap shoulder of a simplified … The term simplified infers that no slat or Fowler flaps are used. … leading-edge flap and a 25% chord simply hinged trailing-…

Purpose Some recent effort showed that usage of Krueger flaps helps to maintain laminar flow in cruise flight. Such flaps are positioned higher relative to the chord to shield the leading edge from the insect contamination during take-off. The flap passes several through critical intermediate position during the deployment to its design position. The purpose of this paper is to analyse the aerodynamics. Design/methodology/approach To better understand such flow phenomena, the combined approach of computational fluid dynamics and experimental methods were used. Flow simulation was performed with in-house finite volume Navier–Stokes solver in fully turbulent unsteady RANS regime. The experimental data were obtained by means of force and pressure measurements and some areas of the flow field were examined with 2 C particle image velocimetry. Findings The airfoil with flap in critical position has a very limited maximum lift coefficient. The maximum achievable lift coefficient during the deployment is significantly affected by the vertical position of the trailing edge of the flap. The most unfavourable position during the deployment is not the flap perpendicular to the chord, but the flap inclined closer to it is the retracted position. Research limitations/implications The flap movement was not simulated either in the simulation or in the experiment. Only intermediate static positions were examined. Practical implications A better understanding of aerodynamic phenomena connected with the deployment of a Krueger flap can contribute to the simpler and lighter of kinematics and also to decrease time-to-market. Originality/value Limited experimental and computational results of Krueger flap in critical positions during the deployment are published in the literature.

… In this study, we demonstrate the design of a Krueger flap as … We generated a family of high-lift systems with Krueger flaps … the high-lift systems with Krueger flap and conventional slat as …

… to investigate the flow physics of Krueger flaps and better understand their acoustic sources. … run on Krueger flap configurations: The first study resolved part of the span of the flap and …

This study focuses on the mechanical design, kinematics and integration assessment of Krueger flap configurations developed for application on a Hybrid Laminar Flow Control (HLFC) Ground Based Demonstrator (GBD). Two high-lift flap geometries were initially explored: articulated “bull-nose” Krueger and a simplified single-panel configuration. Following a series of CAD analyses, the single-panel Krueger with a sharp leading edge was optimized, demonstrating favorable behavior while providing superior integration within the GBD framework. This configuration, coupled with a novel “butterfly” kinematic system, fulfills stringent geometric constraints without requiring modifications to the wing’s leading edge. Moreover, the design enables reliable sealing between the Krueger panel and the wing lower surface, ensuring operational robustness. The work encompasses design studies conducted using CATIA v5 environment. Additional attention was given to geometrical and operational constraints, including insect-shielding requirements, minimum chord dimensions, and stowage limitations, all while maintaining compatibility with suction-based laminar flow technologies. Both configurations—the bull-nose and the sharp leading edge Krueger—are presented, together with the kinematic design philosophy and results based on the space allocation into the wing leading edge . These results establish a practical framework for implementing advanced Krueger flap and kinematic concepts for hybrid laminar flow control technology.

… TE flap deflected to 30 at landing. The configuration was then optimized for takeoff, where the Krueger flap is slotted, … The Krueger flap is fixed at the same position as at landing. The TE …

… high lift wing without nacelle stall is triggered at the outboard sections of the fixed wing. When the nacelles are added the lift … laid on the high lift performance in the linear lift regime and …

… had thin wings/These suffered from leading-edge stall, for which nose droop or slats were a … restrictions we have imposed, the maximum possible lift for any kind of airfoil is 4ir. Since …

Abstract Stall is an important cause closely associated with the flight accidents of commercial aircrafts, and stall lift robustness of HLD (high-lift devices) plays a significant role in flight safety issues. In this study, stall characteristics of the HLD of a wide-body commercial aircraft are simulated and analyzed via DES (detached eddy simulation) method, and the impacts of geometric parameters of the HLD on stall lift characteristics are investigated. Afterwards, stall lift robustness design for the HLD is performed via a proposed inverse method which combines the GRNN (generalized regression neural network) method and PCA (principal component analysis) method. Then the inverse design model is established with the aerodynamic parameters as input and the geometric parameters as output. The PCA method is introduced to reduce the dimension of the input data, while the GRNN is employed to predict the geometric parameters. The design process is iterated with new sample points added in. The validated results via DES method indicate that the finally designed HLD configuration conforms with the design targets very well, and thus the stall lift robustness is improved obviously. More specifically, the average lift coefficient near the stall AoA (angle of attack) is improved by 1.4%, and the variance of the lift coefficients near the stall AoA is reduced by 79%, while the stall AoA remains unchanged.

… of Mach and Reynolds numbers on the stall behavior. Because of the cryogenic … stall, shock-related lift limitations, and flap separations and their influence on achievable maximum lift …

… of high-lift airfoil stall have been presented by the code developers, but we nevertheless consider the accurate prediction of maximum lift … of the complex physics affecting stall . Viscous/ …

… of Mach- and Reynolds number on the stall behavior. Due to the cryogenic … stall, shock related lift limitations and flap separations and their influence on achievable maximum lift …

… to delay the stall of the airfoil based on the observation of the lift and drag curve, implying … our airfoil experiences an earlier stall with a lower maximum lift coefficient. The post-stall lift …

… lift may change with span. Different scale effects may apply on different spanwise stations … the high-lift wing. Unlike 2-D cases, where the type of stall is reflected in the slope of the lift …

… of the stall region is … lift curves have second peak after the stall angle of attack, which is the same as that of 30m/s. In conclusion, the magnitude of the maximum lift coefficient and stall …

… high-lift system for a commercial jet transport are quite high.Increases in lift coefficient and decreases in liftover-drag … Previous results with this model show that it will predict airfoil stall, …

… This paper presents findings from the 3rd AIAA CFD High-Lift Prediction Workshop1 using … with deployed high-lift devices. Case 1 assesses grid convergence on the NASA High-Lift …

Major results and findings of the numerical work package of the European high lift programme EUROLIFT are outlined. The main objective of these studies is to validate and test numerical methods for the prediction of high lift flows for transport aircraft configurations. The activities comprise the assessment of current CFD methods for 3D flows, evaluation of means for code improvement, and transition prediction. All aspects are especially devoted to high lift flow problems. A general capability to predict maximum lift on a simplified wing/fuselage high lift configuration is demonstrated by a variety of different numerical approaches. In general, major shortcomings are the reliability and the accurate simulation of large separation areas and the turn-around time to compute 3D lift polars. Advanced turbulence modelling and numerical solver features, such as the preconditioning technique, show a potential to overcome these deficiencies. Promising results with respect to transition prediction were obtained on a swept high lift wing using a database method. The results obtained in the numerical activities represent major ingredients on the way to a consistent numerical approach for the simulation of transport aircraft high lift configurations including all maximum lift determining effects.

… of the high-lift flow for such … CFD to capture maximum lift, to capture the Reynolds-number dependence of maximum lift and to analyze the vortex phenomena associated with the high-lift …

… Based on these facts, the objectives of this study are to verify CFD method for high-lift … field around high-lift configuration. In this paper, RANS simulation of three-dimensional high-lift …

… CFD approach; some previously computed high-lift CFD … 777 high-lift aircraft in 48 working days; an analysis of the CFD … high-lift aircraft. These results will show that the new overset …

ALCULATING viscous fluid flows over high lift configurations is still a challenge in CFD. The … to obtain realistic CFD solutions. The numerical simulation of the flow field around high lift …

… high-lift systems of modern transport aircraft strongly influence the sizing, economics, and safety of the aircraft … ) associated with modern high-lift systems without sacrificing aerodynamic …

This paper presents a detailed investigation into the performance of the open-source finite volume computational fluid dynamics (CFD) code OpenFOAM for complex high-lift aircraft flows. A range of ...

… Section III of the paper presents the results obtained by different numerical optimization strategies based on high-fidelity methods (CFD), for the design of high-lift systems. Within this “…

… In an aircraft design, the development of effective highlift … to the high-lift flow, and increase the knowledge for computing this kind of flow. This paper discusses CFD prediction for high-lift …

This paper presents an ambitious Computational Fluid Dynamics (CFD) grand challenge problem, including a proposed set of increasingly complex and connected challenge problems, to advance the technological state-of-the-art in the numerical prediction of commercial airplane low-speed, high-lift aerodynamic characteristics and performance. It describes the critical need for a vastly improved computational capability for high-lift airplane design, system development, and product certification, highlights current technology gaps and shortcomings, and details key research and development focus areas where significant progress is required. A key goal of this effort is to energize the aerospace CFD/Aerodynamics communities by coordinating and collaborating across multiple levels of government, industry, academia, and other technology providers to accelerate the use of efficient and robust computational tools to ultimately create products with increased aerodynamic performance that are environmentally cleaner, more fuel efficient, and ensure safe flight while reducing non-recurring product development cost and risk.

Numerical simulations have been performed for a simplified high-lift (SHL) version of the Common Research Model (CRM) configuration, where the Fowler flaps of the conventional high-lift (CRM-HL) configuration are replaced by a set of simple hinged flaps. These hinged flaps are equipped with integrated modular active flow control (AFC) cartridges on the suction surface, and the resulting geometry is known as the CRM-SHL-AFC configuration. The main objective is to make use of AFC devices on the CRM-SHL-AFC configuration to recover the aerodynamic performance (lift) of the CRM-HL configuration. In the current paper, a Lattice Boltzmann method-based computational fluid dynamics (CFD) code, known as PowerFLOW R © is used to simulate the entire flow field associated with the CRM-SHL-AFC configuration equipped with several different types of AFC devices. The transonic version of the PowerFLOW R © code that has been validated for high speed flows is used to accurately simulate the flow field generated by the high-momentum actuators required to mitigate reversed flow regions on the suction surfaces of the main wing and the flap. The numerical solutions predict the expected trends in aerodynamic forces as the actuation levels are increased. More efficient AFC systems and actuator arrangements emerged based on the parametric studies performed prior to a Fall 2018 wind tunnel test. Preliminary comparisons of the numerical solutions for lift and surface pressures are presented here with the experimental data, demonstrating the usefulness of CFD for predicting the flow field and lift characteristics of AFC-enabled high-lift configurations.

… a high-lift configuration aircraft model in JAXA. Main objective of the research is to develop the design methodology for a high-lift … actual aircraft was essential for an advancement of CFD …

… art in the CFD validation of three-dimensional high-lift flows, … Flap Concept for General Aviation Aircraft Applications”, 1st Flow … affecting high-lift systems and suggestions for future CFD …

… , CFD methods, based on the resolution of the Navier–Stokes equations are increasingly used in the estimation of high-lift … sustained international CFD validation exercise for 3D high-lift …

… he subsonic aerodynamic flow-fields associated with three-dimensional, swept, medium-to-high aspect ratio multi-element wings required by commercial and military transport aircraft …

… for transport aircraft high lift system design rely on an extensive use of wind tunnel testing in conjunction with simple Computational Fluid Dynamics (CFD) analysis. The CFD tools …

… Numerical simulations using modern computational fluid dynamics (CFD) codes … high-lift configurations. Shmilovich and Yadlin [5] and Shmilovich and Vatsa [9] demonstrated that CFD …

… sufficient 3D experimental high-lift data; only a limited number of 3D high-lift simulations had … found on an aircraft configured for high lift. Previous high-lift CFD simulations and validation …

… high-lift configurations using an overset grid approach1 3 and the OVERFLOW solver. 4; 5 Calculating the viscous uid ow over high-lift … 6 The diffi culties in simulating high-lift ows come …

… Also the boundary layer thickness is increased in a turbulent flow. Both properties are related to … much easily than do turbulent layers. The transition from laminar to turbulent flow is still a …

… high-lift model is being designed for wind tunnel testing during fiscal year (FY) 2018. This paper will describe the high-lift … currently under development for the wind tunnel test, as well as …

… -scale turbulence. However, it was found that the airfoil of an aircraft during a high-lift phase (… It is therefore interesting to study the stall behavior of a multi-element, high-lift airfoil under …

RANS simulations of a generic ultra-high bypass ratio engine high-lift configuration were conducted in three different environments. The purpose of this study is to assess small scale tests in an atmospheric closed test section wind tunnel regarding transferability to large scale tests in an open-jet wind tunnel. Special emphasis was placed on the flow field in the separation prone region downstream from the extended slat cut-out. Validation with wind tunnel test data shows an adequate agreement with CFD results. The cross-comparison of the three sets of simulations allowed to identify the effects of the Reynolds number and the wind tunnel walls on the flow field separately. The simulations reveal significant blockage effects and corner flow separation induced by the test section walls. By comparison, the Reynolds number effects are negligible. A decrease of the incidence angle for the small scale model allows to successfully reproduce the flow field of the large scale model despite severe wind tunnel wall effects.

… flows and about 1,500 for very turbulent flows. It was assumed that conditions are similar for the flow over an aerofoil, ie for any external flow … high-lift devices such as slots and flaps. …

This paper describes the application of a compressible large-eddy simulation (LES) solver to the flow over the High-Lift Common Research Model (CRM-HL) in landing configuration, a complex external aerodynamic flow configuration with deployed slats, flaps, a flow-through nacelle, and the associated brackets/fairings on the high-lift devices. The bulk Mach number is (0.2) and the mean-aerodynamic-chord-based Reynolds number is typical of a wind tunnel experiment ([Formula: see text]). A key development in these simulations relative to previous work is that this work serves to establish robustness of LES methods to Reynolds number and aircraft configuration. Previous studies focused on the Japan Aerospace Exploration Agency Standard Model, which featured a nearly [Formula: see text] lower Reynolds number than the present CRM-HL investigation and less aggressive wing/slat leading-edge curvature than the CRM-HL geometry, which led to lower leading-edge pressure suction peak magnitudes, both of which led to less stringent grid resolution requirements. In these LES simulations, an algebraic equilibrium wall modeling approach is employed along with a dynamic implementation of the Smagorinsky subgrid-scale model. The calculations are carried out in both a free air setting and one that includes the wind tunnel facility at seven angles of attack at five grid resolution levels, ranging from [Formula: see text] million control volumes. In free air, the solutions show decreasing sensitivity to the grid with each successive refinement level and systematically approach the experimental lift coefficient data as the grid is refined, with the 1.5 billion control volume case showing excellent agreement with the corrected experimental data. The simulations in both free air and in the wind tunnel predict a stall mechanism featuring a large inboard juncture stall and a nose-down break in the pitching moment curve, both of which agree with the experimental observations. The accuracy of the simulations is assessed via comparisons of integrated forces/moments, surface pressures, and surface skin friction visualizations. Graphics processing unit (GPU) acceleration of the charLES solver results in tractable turnaround times that make LES a useful tool in the aerospace industry design cycle. Recent GPU acceleration of the flow solver has made LES solutions that are highly accurate in lift/drag/moment for relevant high-lift aircraft flows achievable within about 5 h of wall time on 600 GPU cores.

A 10%-scale high-lift version of the Common Research Model (CRM-HL) and an Active Flow Control (AFC) version of the model equipped with a simple-hinged flap (CRM-SHLAFC) were successfully tested. The tests were performed in the 14by 22-Foot Subsonic Tunnel (14x22) at the NASA Langley Research Center (LaRC). The CRM-HL has a set of 37° inboard and outboard single-element Fowler flaps. The CRM-SHL-AFC has a set of 50° inboard and 55° outboard simple-hinged flaps equipped with integrated modular AFC cartridges on the flap shoulder. Both high-lift configurations share the same 30° slats and engine nacelle. Three new types of AFC devices were examined: the Double-Row Sweeping Jets (DRSWJ), the Alternating Pulsed Jets (APJ), and the High Efficiency Low Power (HELP) actuators. The DRSWJ and the APJ actuators used two rows of unsteady jets, whereas the HELP actuators used a combination of unsteady and steady jets, to overcome strong adverse pressure gradients while minimizing the mass flow usage. Nozzle pressure ratio, mass flow consumption and the power coefficient, which takes account of both supply air pressure and mass flow usage for the actuators, were used for judging the performance efficiency of the AFC devices. A prestall lift performance degradation for the CRM-HL configuration was resolved with a properly placed nacelle chine. The configuration with nacelle chine was chosen as the representative reference conventional high-lift case for comparison with the CRMSHL-AFC. The AFC-induced lift coefficient increment (DCL) was maintained for the entire lift curve over the CRM-SHL-AFC case with no AFC for almost all flow-control cases examined. The lift curve of the reference CRM-HL have a slightly steeper slope compared to those of the CRM-SHL-AFC configurations. The HELP actuation concept was extremely effective in controlling flow separation in the “linear region” of the curves comparing lift coefficient to mass flow rate. The HELP actuation achieved a targeted DCL of 0.50 using a moderate amount of mass flow and supply air pressure. The CRM-SHL-AFC configuration equipped with HELP actuation was able to match or exceed the lift performance of the reference conventional high-lift configuration (i.e., CRM-HL equipped with a nacelle chine), thus meeting the NASA Advanced Air Transport Technology (AATT) project goal.

… flow physics. In particular, the multiple elements with small gaps give rise to multiple wakes, flow separation, laminar/turbulent … The numerical simulation of the flowfield around high-lift …

… in the results of wind tunnel tests. The first concern^ the application of wind tunnel blockage … The second problem arises during ground effects testing over a "onmoving tunnel floor or …

… to visualize the laminar-to-turbulent boundary-layer transition … To visualize laminar and turbulent regions on a TSP painted … a high-lift wind tunnel model that - for a selected flow state …

… flow of 30P-30N multi-element airfoil, the main purpose is to … Liu Peiqing, on a plane wing airfoil mounted control different … coefficient and drag coefficient of multi-element airfoil, but will …

… experimental optimization of multi-element airfoils. A modern … modeling approach to multielement airfoil optimization at near… Flow interference was felt to be minimal and not a signifi …

… To promote two-dimensional flow over the model in view of its low aspect ratio and strong wall-model aerodynamic interference, a new side-wall boundary layer control (BLC) system …

Для численного моделирования аэродинамики многоэлементного профиля применяются осредненные по Рейнольдсу уравнения Навье-Стокса несжимаемой среды, замкнутые однопараметрической дифференциальной моделью турбулентности Spalart-Allmaras. Система исходных уравнений записывалась относительно произвольной криволинейной системы координат. Согласование полей давления и скорости осуществлялось с помощью метода искусственной сжимаемости, модифицированного для расчета нестационарных задач. Интегрирование системы исходных уравнений проводилось численно с использованием метода контрольного объема. Для конвективных потоков использовалась противопоточная аппроксимация Rogers-Kwak, основанная на схеме Roe третьего порядка точности. В модели турбулентности для аппроксимации конвективных слагаемых применялась схема TVD с ограничителем потоков ISNAS третьего порядка. Представлены результаты расчета турбулентного обтекания многоэлементного профиля в широком диапазоне углов атаки. В результате проведенных исследований выполнен анализ поля течения вокруг многоэлементного профиля, коэффициентов давления, подъемной силы и силы лобового сопротивления. Выделены физические особенности структуры течения при обтекании многоэлементного профиля 30P30N. В исследуемом диапазоне углов атаки обтекание профиля во взлетно-посадочной конфигурации носит стационарный характер за исключением областей, где отрыв потока происходит с острых кромок, таких как внутренняя часть предкрылка и область в хвостовой части основного профиля. Внутри этих областей возникают рециркуляционные течения. С увеличением угла атаки размеры отрывной зоны на внутренней поверхности предкрылка уменьшаются, а в хвостовой части основного профиля остаются практически постоянными. На верхней поверхности основного профиля формируется струя воздуха вследствие ускорения потока между предкрылком и передней кромкой основного профиля. Наличие зазора между основным профилем и закрылком приводит к интерференции струйных течений на верхней поверхности закрылка. Показано, что взлетно-посадочная конфигурация обладает более высокими значениями коэффициента подъемной силы, чем крейсерская конфигурация, особенно на больших углах атаки. Результаты расчетов удовлетворительно согласуются с данными других авторов

… Therefore, the best way to calibrate a code with this dataset is to use experimental data which has not been corrected for wall interference or tunnel blockage effects and model the wind …

Abstract Based on the response surface methodology and the grid method combining with numerical simulation of Reynolds-averaged Navier-Stokes equations,the lift-enhancing optimizations of three-element airfoil parameters and its air-blowing flow control parameters are carried out. The finite volume method is adopted to discretize the Reynolds-averaged Navier-Stokes equations in space, the second-order upwind scheme is used in time advance, and SST k – ω turbulence model is used to compute turbulence viscosity. The objective function is obtained with the response surface methodology,and the optimal solution is made using nonlinear programming with the grid method. On the base of multi-element airfoil parameter optimization, the influencing parameters ofair-blowing effect are analyzed and selected, the optimization design variables are determinedas the air-blowing slotlocations, angles and air-blowing momentumcoefficients, and lift-enhancing aerodynamic optimization ofair-blowing flow control parameters on multi-element airfoil is completed. It is shown from the results that the optimization method combining response surface methodology with the grid method is fit for parameter optimizationof multi-element airfoil and its flow control with air-blowing on the flap forlift-enhancing; the flow around the multi-element airfoil can be well controlled and its aerodynamic performance is greatly improved, then the maximum lift coefficient achieves 4.9589which is usually the maximum lift coefficient of the five-element airfoil; after optimization the air-blowing slot anglesare of about 20° on the trailing edge flapsand the air-blowing momentum coefficientsof slotsexist an optimum value.

… This paper describes resuits obtained for small (sub-boundary-layer) vane-type vortex generators mounted on a multi-element airfoil in a landing configuration. Measurements include lift…

Abstract Experimental measurements using Particle Image Velocimetry were carried out to understand the flow characteristics of a 30P30N high-lift airfoil with and without slat cove fillers. The tests were carried out for the 30P30N airfoil with a retracted chord of c = 0.35 , at angles of attack of α = 6 ∘ and 12 ∘ , and for a chord-based Reynolds number of R e c = 7.0 × 10 5 . The wall pressure fluctuation results show that the use of slat cove fillers eliminates the slat tonal noise component. The results of the mean flow fields such as the normalized mean velocity, Reynolds stress components, and turbulent kinetic energy are presented for the baseline, half-slat cove filler, and slat cove filler configurations. The velocity contour results with streamlines showed a recirculation region within the slat cavity. The use of the half-slat cove filler reduced the size of the recirculation region and the use of the slat cove filler eliminated the recirculation region. The mean velocity and turbulent kinetic energy profiles at the slat wake showed insignificant difference between the three tested configurations. The Particle Image Velocimetry results were further analyzed using Proper Orthogonal Decomposition. The results showed that the first two eigenmodes of the vorticity with the highest energy were contained within the slat shear layer and vortex shedding emanating from the slat cusp for the baseline case. The energy levels were distributed over the slat shear layer for the half-slat cove filler and slat cove filler configurations as the vortex shedding is suppressed by the use of the slat cove fillers.

<div class="htmlview paragraph">A wind-tunnel test was conducted for an unswept wing with a half-span Fowler flap. Surface pressures, flow visualization, and wake surveys were obtained for two flap riggings representative of landing configurations. The primary influence of the half-span flap is to create spanwise pressure gradients on the main element and flap. Pressure distributions near the flap tip indicate the presence of two distinct suction peaks on the upper surface. Flow visualization using smoke verifies the existence of two co-rotating vortices near the flap tip that merge before reaching the trailing edge. Seven-hole-probe wake surveys yield values for both profile and induced drag.</div>

A three-dimensional computational fluid dynamics analysis of low Reynolds number [ O ( 10 4 )] flow over a 30P30N three-element high lift wing is carried out using a high-order spectral element method. In this article, we study the flow in the slat cove region and the slat wake/shear layer interaction. Vortical structures, identified in the computations, are very similar to those visualized in recent experiments. For Reynolds numbers below a critical interval (found in recent experiments), Gortler vortices are observed in the slat wake, while for Reynolds numbers above the critical interval, a roll-up is observed in the slat cove and both streamwise and spanwise vortices form in the slat wake. Prior to the formation of Gortler and roll-up vortices, three-dimensional tongue- or rib-like vortex shapes, similar to those found in the wake of bluff bodies, are observed in the slat cove and promote transition to three-dimensional flow. Above the critical interval, streaks and spanwise vortices are observed to dominate the slat wake and lead to the formation of hairpin vortices which contribute to the transition to turbulence. Integral flow parameters such as lift, drag, and pressure coefficients are analyzed in the range of Reynolds numbers studied.

… In order to maintain two-dimensionality within the slat cove and flap cove regions, no … The pressure distribution with respect to model the coordinates for the Baseline case at the …

… A total of 160 pressure tubes (144 for pressure distributions, … pressure (ESP) modules that were located in the wing cove … slat pressure distributions for the 15and 40-deg-flap setting (…

… The structured grid layer is employed to cover the region where relevant viscous phenomena … From the pressure distributions, one can see that low pressure is better distributed over the …

… The time-averaged pressure coefficient Cp distribution results extracted along the mid-… flap validate very well with the experimental data. The close-up view of the pressure distribution …

… Cµ) on the pressure distribution over the airfoil across the range of cove gaps are shown in … peak forms near the flap cove (x/c = 0.9) and an adverse pressure gradient is present along a …

… Previous wind tunnel studies on a model wing section had shown that a broadband slat … contour and thus avoids turbulence spots to merge into the accelerated flow in the gap between …