| Autor(en) | El Sayed M., Yosef | Oswald, Philipp | Sattler, Stephan | Kumar, Pradeep | Radespiel, Rolf | Behr, Christian | Sinapius, Michael | Petersen, Jan | Wierach, Peter | Quade, Markus | Abel, Markus | Noack, Bernd R. | Semaan, Richard | Wierach, Peter | Radespiel, Rolf |
|---|---|
| Titel | Open- and closed-loop control investigations of unsteady Coanda actuation on a high-lift configuration |
| Herausgeber | AIAA Paper |
| Erscheinungsjahr | 2018 |
| Abstract | The present study investigates the lift gains and losses generated by the superposition of a periodic spanwise-synchronous and spanwise-varied actuation component onto a steady component on an airfoil with a highly deflected Coanda flap. The unsteady actuation is provided by 33 specially-designed lip segments that deliver actuation frequencies up to 300 Hz and actuation amplitudes up to 100% of the mean blowing intensity. The results demonstrate the benefits of superimposing a periodic spanwise-synchronous component onto the steady actuation component for a separated or partially-attached flow, where up to ∆C l = 0.2 lift increase is achieved. Square wave motion is shown to be more robust than sinusoidal motion with a broader lift gain region. Spanwise traveling wave yield the highest lift gains with ∆C l = 0.25 with a relatively slow wave frequency and long wavelength. Machine learning control has also been successfully implemented with promising initial results. |
| Autor(en) | El Sayed M., Yosef | Semaan, Richard | Radespiel, Rolf |
|---|---|
| Titel | Sparse Modeling of the Lift Gains of a High-Lift Configuration with Periodic Coanda Blowing |
| Herausgeber | AIAA Paper |
| Erscheinungsjahr | 2018 |
| Abstract | The present study investigates and models the lift gains generated by the superposition of a periodic actuation component on a steady component on an airfoil with highly deflected Coanda flap. The periodic actuation is provided by two synchronized specially-modified valves that deliver actuation frequency up to 30 Hz and actuation amplitude up to 20% of the mean blowing intensity. The lift gains response surface is modeled using a data-driven sparse identification approach. The results clearly demonstrate the benefits of superimposing a periodic component on the steady actuation component for a separated or partially-attached flow, where up to ∆C l = 0.5 lift increase is achieved. On the other hand, this same superimposition for an attached flow is detrimental to the lift, with up to ∆C l = −0.3 lift reduction compared to steady actuation with similar blowing intensity. |
| Autor(en) | El Sayed, Yosef | Beck, Nils | Kumar, Pradeep | Semaan, Richard | Radespiel, Rolf |
|---|---|
| Titel | Challenges in the Experimental Quantification of the Momentum Coefficient of Circulation Controlled Wings. |
| Herausgeber | New Results in Numerical and Experimental Fluid Mechanics XI. Springer, Cham, 2018. S. 533-543 |
| Erscheinungsjahr | 2018 |
| Abstract | Based on three experiments in wind and water tunnels, the challenges in quantifying the momentum coefficient are investigated and solutions to minimize the associated uncertainties are proposed. It is shown that including the viscous losses, determining the blowing slot height changes under loading conditions, as well as measuring the jet pressure is crucial for accurately quantifying the momentum coefficient. |
| Autor(en) | François, Daniela | Radespiel, Rolf | Semaan, Richard |
|---|---|
| Titel | Numerical Investigations of Spanwise-Varied Unsteady Coanda Actuation on High-Lift Configuration |
| Herausgeber | AIAA journal of aircraft |
| Erscheinungsjahr | 2018 |
| Abstract | The present study investigates possible lift gains generated by spanwise-varied blowing on a high-lift configuration equipped with a droop nose and a Coanda flap. Two types of numerical simulations are performed and compared: unsteady Reynolds-averaged Navier–Stokes simulations and improved delayed detached-eddy simulations with algebraic sensors. The unsteady Reynolds-averaged Navier–Stokes simulations achieve the best actuation settings at F+=0.5. No relevant sensitivity an actuation amplitude of 25% of the jet slit height and an actuation frequency of F is detected with regard to the phase shift of the actuated spanwise segments. In contrast, the algebraic improved delayed detached-eddy simulations results show clear sensitivity to actuation phase shift. The algebraic improved delayed detached-eddy scale-resolving simulations also exhibit different wake dynamics from those of unsteady Reynolds-averaged Navier–Stokes. Based on both the unsteady Reynolds-averaged Navier–Stokes and algebraic improved delayed detached-eddy simulations results, this study demonstrates the benefits that the superposition of a two-dimensional periodic actuation component (no phase shift between actuated segments) has on the lift. The benefits of three-dimensional segmented actuation remain unknown and await further research. |
| Autor(en) | Semaan, Richard | El Sayed M., Yosef | Radespiel, Rolf |
|---|---|
| Titel | Sparse Model of the Lift Gains of a High-Lift Configuration with Unsteady Coanda Blowing |
| Herausgeber | Active Flow and Combustion Control 2018 |
| Erscheinungsjahr | 2018 |
| Abstract | The present study investigates and models the lift gains and losses generated by the superposition of a periodic actuation component onto a steady component on an airfoil with a highly deflected Coanda flap. The periodic actuation is provided by two synchronized specially-designed valves that deliver actuation frequencies up to 30 Hz and actuation amplitudes up to 20% of the mean blowing intensity. The lift gains/losses response surface is modeled using a data-driven sparse identification approach. The results clearly demonstrate the benefits of superimposing a periodic component onto the steady actuation component for a separated or partially-attached flow, where up to ΔC l = 0.47 lift increase is achieved. On the other hand, this same superimposition for an attached flow is detrimental to the lift, with up to ΔC l = −0.3 lift reduction compared to steady actuation with similar blowing intensity is observed. |
| Autor(en) | Vasista, Srinivas | Nolte, Felix | Monner, Hans Peter | Horst, Peter | Burnazzi, Marco |
|---|---|
| Titel | Three-dimensional design of a large-displacement morphing wing droop nose device |
| Herausgeber | Journal of Intelligent Material Systems and Structures, DOI: 10.1177/1045389X18770863 |
| Erscheinungsjahr | 2018 |
| Abstract | The numerical three-dimensional structural design of a large-displacement flexible morphing wing leading edge, otherwise known as a droop nose, is presented in this article. The droop nose is an essential component of a novel internally blown high-lift system for a transport aircraft to delay stall and reduce internal compressor requirements. A design chain consisting of optimization procedures was used to arrive at the structural design of the droop nose composed of a composite fiberglass skin with integral stringers and supporting kinematic mechanisms. The optimization tools aim to produce a design with minimal error to the critical target shapes. A maximum final error of 10.09 mm between calculated and target trajectories of the stringers was found after the kinematic optimization stage. After inputting the kinematic optimization results into the skin optimization stage and solving, a maximum error in the order of 13 mm and curvature difference 0.0028 1/mm were calculated, occurring in the outboard region. Prior two-dimensional analyses with similar shape deviations showed 0.4% lift reduction though further three-dimensional investigations are required. Concepts for integrating industrial requirements abrasion and lightning strike protection and in-flight de-icing into a multifunctional skin show promise and the resulting aerodynamic surface quality was found to be adequate. |
| Autor(en) | El Sayed, Yosef | Semaan, Richard | Radespiel, Rolf |
|---|---|
| Titel | Open Loop Control on a Coanda Flap Water Tunnel Model |
| Herausgeber | 35th AIAA Applied Aerodynamics Conference. 2017 |
| Erscheinungsjahr | 2017 |
| Abstract | Water tunnel experiments are conducted to assess the lift gains of superimposed steady and periodic unsteady actuation on an airfoil with a highly deflected Coanda flap. The periodic actuation is provided by two synchronized specially-modified valves that deliver actuation frequencies up to 30Hz and actuation amplitudes up to 20% of the mean blowing intensity. The results clearly demonstrate the benefits of superimposing a periodic forcing component on a steady blowing component for a separated or partially-attached flow, where up to 14% lift increase is achieved. On the other hand, this same superimposition for an attached flow is detrimental to the lift, with up to 8.2% lift reduction compared to steady actuation with similar blowing intensity. |
| Autor(en) | El Sayed, Yosef | Semaan, Richard | Sattler, Stephan | Radespiel, Rolf |
|---|---|
| Titel | Wake characterization of a circulation control wing |
| Herausgeber | Experiments in Fluids, 2017, 58. Jg., Nr. 10, S. 144. |
| Erscheinungsjahr | 2017 |
| Abstract | We propose a three-pronged methodology to characterise the wake behind a circulation control wing. The study relies on time resolved particle image velocimetry (TR-PIV) measurements in a water tunnel for a range of blowing intensities. The first method is the well-known proper orthogonal decomposition (POD). The second tool is a new scheme that we introduce, in which the peak power spectrum frequency is determined at every location, and contour plotted. Finally, a modified Q-criterion vortex detection and quantification method is presented. The results show the complementary advantage of the three methods in analysing wake flows with varying conditions. |
| Autor(en) | Kauth, Felix | Narjes, Gerrit | Müller, Jan | Seume, Jörg | Vasista, Srinivas | Müller, Thomas | Francois, Daniela | El Sayed, Yosef | Semaan, Richard | Behr, Christian | Schwerter, Martin | Leester-Schädel, Monika | Nolte, Felix | Giesecke, Daniel | Atalayer, Caglar | Radespiel, Rolf |
|---|---|
| Titel | Progress in Efficient High-Lift |
| Herausgeber | AIAA AVIATION Forum, 35th AIAA Applied Aerodynamics Conference, Denver, 2017 |
| Erscheinungsjahr | 2017 |
| Abstract | This paper presents some of the progress in research on efficient high-lift systems for future civil aircraft achieved by the Coordinated Research Centre CRC 880 sponsored by the German Research Foundation. Several new approaches to increasing the lift are applied as part of the design of a reference aircraft with short take-off and landing ca- pability: The numerically predicted positive effect of Coanda jet blowing at the trailing edge flap is validated in water tunnel experiments. Robust miniature pressure and hot- film sensors are developed for the closed-loop control of a piezo-actuated blowing lip. A flexible leading-edge device utilizes composite materials, for which new structural designs are developed. Additionally, a potential de-icing system, as well as a lightning-strike pro- tection are presented. A high power-density electrically driven compressor with a broad operating range is designed to provide the blowing airflow. Different propulsion systems for the reference aircraft are evaluated. An ultra-high bypass ratio engine is considered to be most promising, and thus a preliminary fan stage design process is established. The rotor dynamic influences of the engine on the aircraft structure are investigated through a hybrid approach using a multibody model and modal reduction. |
| Autor(en) | Semaan, Richard |
|---|---|
| Titel | Optimal sensor placement using machine learning |
| Herausgeber | Computers and Fluids |
| Erscheinungsjahr | 2017 |
| Abstract | A new method for optimal sensor placement based on input variables importance of machine learned models is proposed. With its simplicity, adaptivity, and low computational cost, the method offers many advantages over existing approaches. The method is implemented on flow over an airfoil equipped with a Coanda actuator. The analysis is based on flow field data obtained from two-dimensional unsteady Reynolds averaged Navier–Stokes (URANS) simulations with different actuation conditions. The optimal sensor locations are compared against the current de-facto standard of maximum POD modal amplitude location, and against a brute force approach that scans all possible sensor combinations. The results show that both the flow conditions and the type of sensor have an effect on the optimal sensor placement, whereas the choice of the response function appears to have limited influence. |
| Autor(en) | Burnazzi, Marco | Thiemeier, Jakob | Radespiel, Rolf |
|---|---|
| Titel | Numerical Stall Behavior Investigation of an Aircraft Equipped with Coanda Flap and Droop Nose |
| Herausgeber | New Results in Numerical and Experimental Fluid Mechanics X |
| Erscheinungsjahr | 2016 |
| Abstract | An active high-lift set up is employed on a wing-body aircraft configuration and the stall behavior is analyzed by means of CFD RANS simulations. The high-lift system is composed of a trailing-edge gap-less Coanda flap and a leading-edge flexible droop nose. The effect of the leading-edge device is studied by using comparisons with the cruise leading-edge configuration. Comparisons with previous 2D simulations highlight lower lift performances for the wing section of the 3D model with respect to the airfoil data. This is due to 3D flow dynamics that limit the lift generated by the wing and induce stall with mechanisms not observed in 2D. Cross flow at the wing leading edge, or over the suction side of the wing root, increase the boundary layer thickness over the wing, thus reducing the efficiency of the Coanda flap. |
| Autor(en) | Radespiel, Rolf | Burnazzi, Marco | Casper, Marcus | Scholz, Peter |
|---|---|
| Titel | Active Flow control for high lift with steady blowing |
| Herausgeber | The Aeronautical Journal, 120, pp 171-200 doi:10.1017/aer.2015.7 |
| Erscheinungsjahr | 2016 |
| Abstract | Active flow control with steady blowing is a powerful means to suppress or delay turbulent flow separation resulting from adverse pressure gradients in the flow field. The paper reviews recent progress with two promising approaches focused on improving maximum lift of transport aircraft wings. While the tangential blowing of thin wall jets uses a slot along the wing span to generate largely scalable momentum overshoots close to the wall, the alternate method re-arranges momentum in strongly loaded boundary layers, by taking advantage of blowing from localized orifices, that can place longitudinal vorticity at desired locations. Analysis of computational and experimental results for both approaches identifies flow physics, parameter sensitivities and scaling behaviors. It appears that the different approaches are also different in their potentials to provide extra lift. Longitudinal vortex generator jets are limited in the maximum lift gains that can be obtained. This is because the devices are limited to rearrange momentum, which inherently requires momentum to exist at some place, where the vortices have some influence. The potentials of providing lift increases by tangential blowing are larger, as this technique can provide large flow turning on airfoils and wings by exploiting the Coanda effect with the wall jet. |
| Autor(en) | Semaan, Richard | Kumar, Pradeep | Burnazzi, Marco | Tissot, Gilles | Cordier, Laurent | Noack, Bernd R. |
|---|---|
| Titel | Reduced-order modelling of the flow around a high-lift configuration with unsteady Coanda blowing |
| Herausgeber | Journal of Fluid Mechanics (2016), vol. 800, pp. 72–110. |
| Erscheinungsjahr | 2016 |
| Abstract | We propose a hierarchy of low-dimensional proper orthogonal decomposition (POD) models for the transient and post-transient flow around a high-lift airfoil with unsteady Coanda blowing over the trailing edge. The modal expansion comprises actuation modes as a lifting method for wall actuation following Graham et al. (Intl J. Numer. Meth. Engng, vol. 44 (7), 1999, pp. 945–972) and Kasnako ̆glu et al. (Intl J. Control, vol. 81 (9), 2008, pp. 1475–1492). A novel element is separate actuation modes for different frequencies. The structure of the dynamic model rests on a Galerkin projection using the Navier–Stokes equations, simplifying mean-field considerations, and a stochastic term representing the background turbulence. The model parameters are identified with a data assimilation (4D-Var) method. We propose a model hierarchy from a linear oscillator explaining the suppression of vortex shedding by blowing to a fully nonlinear model resolving unactuated and actuated transients with steady and high-frequency modulation of blowing. The models’ accuracy is assessed through the mode amplitudes and an estimator for the lift coefficient. The robustness of the model is physically justified, and then observed for the training and the validation dataset. |
| Autor(en) | Beutel, Tobias | Sattler, Stefan | El Sayed, Yosef | Schwerter, Martin | Zander, Martin | Büttgenbach, Stephanus | Leester-Schädel, Monika | Radespiel, Rolf | Sinapius, Michael | Radespiel, Rolf |
|---|---|
| Titel | Design of a high-lift experiment in water including active flow control |
| Herausgeber | Smart Materials and Structures, Vol. 23 , 077004 (10pp) |
| Erscheinungsjahr | 2014 |
| Abstract | This paper describes the structural design of an active flow-control experiment. The aim of the experiment is to investigate the increase in efficiency of an internally blown Coanda flap using unsteady blowing. The system uses tailor-made microelectromechanical (MEMS) pressure sensors to determine the state of the oncoming flow and an actuated lip to regulate the mass flow and velocity of a stream near a wall over the internally blown flap. Sensors and actuators are integrated into a highly loaded system that is extremely compact. The sensors are connected to a bus system that feeds the data into a real-time control system. The piezoelectric actuators using the d33 effect at a comparable low voltage of 120 V are integrated into a lip that controls the blowout slot height. The system is designed for closed-loop control that efficiently avoids flow separation on the Coanda flap. The setup is designed for water-tunnel experiments in order to reduce the free-stream velocity and the system’s control frequency by a factor of 10 compared with that in air. This paper outlines the function and verification of the system’s main components and their development. |
| Autor(en) | Burnazzi, Marco | Kumar, Pradeep | Semaan, Richard | Radespiel, Rolf |
|---|---|
| Titel | NUMERICAL ASSESSMENT OF TWO PERIODIC ACTUATION APPROACHES FOR FLOW SEPARATION CONTROL |
| Herausgeber | DLRK Kongress, 2014, Augsburg |
| Erscheinungsjahr | 2014 |
| Abstract | This study investigates two actuation approaches to implement periodic tangential blowing over a gap-less high-lift flap. The high-lift configuration is composed of an active simple-hinged Coanda flap and a leading-edge droop nose device. The two approaches compared in the present work are based on different methods for obtaining a periodic oscillation of the Coanda jet. The first approach varies the jet momentum by periodically changing the slot exit section. As a result the jet velocity remains approximately constant and the mass flow drives the momentum oscillations. In the second approach, the total pressure inside the jet plenum is varied, leading to different jet velocities and mass flows. These two approaches create jets with different characteristics, which interact differently with the flow over the flap. The analysis is based on flow-field data obtained from 2D unsteady Reynolds averaged Navier-Stokes (uRANS) simulations. The two actuation approaches are compared for two different frequencies and two different amplitudes. The results show that similar flow mechanisms are obtained by the two approaches, and the resulting lift performances are comparable. However, in the case of large amplitude signals the lip-motion approach lead to smaller fluctuations of lift coefficient and to a slightly higher average lift. |
| Autor(en) | Burnazzi, Marco | Radespiel, Rolf |
|---|---|
| Titel | Design and Analysis of a Droop Nose for Coanda Flap Applications |
| Herausgeber | AIAA JOURNAL OF AIRCRAFT Vol. 51, No. 5, DOI: 10.2514/1.C032434 |
| Erscheinungsjahr | 2014 |
| Abstract | The present study describes the fundamentals of droop nose design for improving the aerodynamics of airfoils with active high-lift using an internally blown Coanda-type flap. The main objectives are to increase the stall angle of attack and reduce the power required by the high-lift system. A two-dimensional sensitivity analysis explores the effects of varying airfoil camber and thickness in the first 20% of the chord. The resulting droop nose configuration improves the maximum lift coefficient by about 20% and increases the stall angle of attack by around 10–15 deg. A target lift coefficient of about 4.7 is reached with 28% less jet momentum coefficient, compared to the clean nose. As the modified leading-edge geometry presents different stall mechanisms, the aerodynamic response to variations of jet momentum is also different. In particular, for a jet momentum coefficient above 0.035, the stall angle of attack increases with jet momentum, in contrast with the behavior observed with the clean nose. |
| Autor(en) | Burnazzi, Marco | Radespiel, Rolf |
|---|---|
| Titel | Assessment of leading-edge devices for stall delay on an airfoil with active circulation control |
| Herausgeber | CEAS Aeronaut J (2014) 5:359–385 DOI 10.1007/s13272-014-0112-5 |
| Erscheinungsjahr | 2014 |
| Abstract | The use of active, internally blown high-lift flaps causes the reduction of the stall angle of attack, because of the strong suction peak generated at the leading-edge. This problem is usually addressed by employing movable leading-edge devices, which improve the pressure distribution, increase the stall angle of attack, and also enhance the maximum lift coefficient. Classical leading-edge devices are the hinged droop nose or the more effective slat with a gap. The flow distortions generated by the gap become an important source of noise during approach and landing phases. Based on these considerations, the present work aims at evaluating the potentials of gap-less droop nose devices designed for improving the aerodynamics of airfoils with active high lift. Both conventional leading-edge flaps and flexible droop noses are investigated. Flexible droop nose configurations are obtained by smoothly morphing the baseline leading-edge shape. Increasing the stall angle of attack and reducing the power required by the active high-lift system are the main objectives. The sensitivities of the investigated geometries are described, as well as the physical phenomena that rule the aerodynamic performance. The most promising droop-nose configurations are compared with a conventional slat device as well as with the clean leading-edge. The response of the different configurations to different blowing rates and angles of attack are compared and the stalling mechanisms are analyzed. |
| Autor(en) | Burnazzi, Marco | Radespiel, Rolf |
|---|---|
| Titel | Synergies between suction and blowing for active high-lift flaps |
| Herausgeber | CEAS Aeronaut Journal, DOI 10.1007/s13272-014-0146-8 |
| Erscheinungsjahr | 2014 |
| Abstract | The present 2-D CFD study investigates aero- dynamic means for improving the power efficiency of an active high-lift system for commercial aircraft. The high- lift configuration consists of a simple-hinged active Coanda flap, a suction slot, and a flexible droop nose device. The power required to implement circulation control is pro- vided by electrically driven compact compressors posi- tioned along the wing behind the wingbox. The compact compressors receive air from the suction slot, which also represents an opportunity to increase the aerodynamic performance of the airfoil. The present work investigates the aerodynamic sensitivities of shape and location of the suction slot in relation to the maximum lift performance of the airfoil. The main purpose of the study is the reduction of the compressor power required to achieve a target lift coefficient. The compressor power requirements can be reduced in two ways: obtaining a high total pressure at the end of the suction duct (compressor inlet) and reducing the momentum needed by the Coanda jet to avoid flow sepa- ration from the flap. These two objectives define the guideline of the suction slot design. As a result, a jet momentum reduction of 16 % was achieved for a target lift coefficient of 5 with respect to the same configuration without suction. Furthermore, the study yielded physical insight into the aerodynamic interaction between the two active flow control devices. |
| Autor(en) | El Sayed M, Yosef | Semaan, Richard |
|---|---|
| Titel | Progress toward Closed Loop Control of a Flow around an Airfoil with Coanda Blowing |
| Herausgeber | Springer, ICOMASeF, Prato (Tuscany) Italy, 2014 |
| Erscheinungsjahr | 2014 |
| Abstract | Progress toward developing a closed loop control of flow around an airfoil with a Coanda flap is presented. Two loop components were addressed and analysed for the reference no-blowing case: the estimator and its input signal. For the estimator, a Proper Orthogonal Decomposition (POD) Galerkin model based on unsteady Reynolds averaged Navier-Stocks (uRANS) data was evaluated. To compensate for the unresolved dissipative scales in uRANS and for truncation error, the POD Galerkin model was calibrated by introducing an eddy viscosity term. The cali-brated POD Galerkin model succeeded in replicating the time coefficients of the first two modes but failed to replicate the higher modes. The sensor location over the flap was optimized using modified Linear Stochastic Estimation (mLSE). With an optimal sensor placement it was possible to determine the state of the flow more accurately than for the same number of evenly spaced sensors. |
| Autor(en) | Semaan, Richard | El Sayed, Yosef | Sattler, Stephan | Sultana, Kaniz | Burnazzi, Marco | Scholz, Peter | Radespiel, Rolf |
|---|---|
| Titel | A Generalized Reduced-Order Model of Flow around an Airfoil with Circulation Control |
| Herausgeber | AIAA-2014-2517, 7th AIAA Flow Control Conference, 16-20 June, 2014, Atlanta, GA |
| Erscheinungsjahr | 2014 |
| Abstract | A low-dimensional generalized model is proposed for a flow around an airfoil with circulation control, describing natural vortex shedding and steady actuation. The suggested application range of the model extends from the un-actuated natural state to the strongly actuated near-steady state. The form of the dynamical system has been based on generalized mean-field consideration. Time resolved PIV snapshots are employed to derive the POD time coefficients and to calibrate the system parameters. The model is solely dependent on the actuation blowing momentum coefficient, and makes a good candidate for flow control applications. |
| Autor(en) | Burnazzi, Marco | Radespiel, Rolf |
|---|---|
| Titel | Design of a Droopnose Configuration for a Coanda Active Flap Application |
| Herausgeber | 51th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition, Dallas (TX), AIAA 2013-0487 |
| Erscheinungsjahr | 2013 |
| Abstract | The present study describes the fundamentals of droopnose design for improving the aerodynamics of airfoils with active high-lift using a Coanda flap. Increasing the stall angle of attack and reducing the power required by the high-lift system, are the main objectives. The sensitivities of the investigated geometries are described, as well as the physical phenomena that rule the aerodynamic performance. |
| Autor(en) | Burnazzi, Marco | Radespiel, Rolf |
|---|---|
| Titel | SYNERGIES OF SUCTION AND BLOWING FOR ACTIVE HIGH-LIFT FLAPS |
| Herausgeber | DLRK 2013 - German Aerospace Congress 2013, Stuttgart. |
| Erscheinungsjahr | 2013 |
| Abstract | The present work represents an advanced step in the multidisciplinary design of an active high-lift system for commercial aircraft. The airfoil configuration developed within the framework of the Collaborative Research Centre SFB880 is composed of an active Coanda flap and a droopnose device. The power required to implement circulation control is provided by electrically-driven compact compressors, positioned along the wing behind the wingbox. This solution could reduce the additional engine power needed for the active high- lift system. Air is provided to the compact compressors by means of a suction slot located on the suction side of the airfoil, which represents an opportunity to increase the aerodynamic performance of the airfoil. The present work investigates the aerodynamic sensitivities of shape and location of the suction slot, in relation to the high-lift performance of the airfoil and to the total pressure recovery achieved at the end of the suction duct. A significant benefit is achieved by suction and the presented analysis yields physical insight into the flow dynamics around the airfoil. |
| Autor(en) | Müller, Lars | Kozulovic, Dragan | Radespiel, Rolf |
|---|---|
| Titel | Aerodynamic Performance of an Over-thewing Propeller Configuration at Increasing Mach Number |
| Herausgeber | Proc. Deutscher Luft- und Raumfahrtkongress, Stuttgart, Germany |
| Erscheinungsjahr | 2013 |
| Abstract | Over-the-wing propeller configurations show increased climb performance and, through effective acoustic shielding, reduced noise emissions when compared to a conventional tractor configuration. The main aero-dynamic mechanisms could be identified by steady flow simulations of a simplified geometry and actuator disk. At takeoff, where the thrust coefficient is very high, the drag of the wing decreases much stronger than the thrust of the propeller. This paper investigates the cruise conditions where the thrust coefficient is by one order of magnitude lower. The numerical results give evidence that, at a moderate flight Mach number of 0.6, the beneficial influence of the over-the-wing propeller on the drag coefficient of the wing is negligibly small. On the other hand, the propeller loses an even larger relative amount of efficiency due to compressibility effects on the inflow velocity above the wing. As a result, the propulsive efficiency of a channel wing configu-ration is 16% smaller than the tractor value, increasing the fuel consumption by a similar percentage. Semi-empirical correlations show that, even at very low Mach numbers, a drawback of at least 5% remains. How-ever, improvements concerning the propeller position and wing shape indicate a potential to restore two thirds of the performance loss. |
| Autor(en) | Seume, Jörg | Burnazzi, Marco | Schwerter, Martin | Behr, Christian | Rudenko, Anton | Schmitz, Andre | Dörbaum, Michael | Atalayer, Caglar |
|---|---|
| Titel | SFB 880 – Efficient High Lift |
| Herausgeber | 62nd DLRK, Stuttgart, Germany, 2013 |
| Erscheinungsjahr | 2013 |
| Abstract | The collaborative research center (Sonderforschungsbereich, abbreviated SFB) 880 investigates the fundamentals of high-lift generation for future civil aircraft, focusing on the fields of aeroacoustics, lift generation and flight dynamics. The present paper addresses the research on efficient lift generation which is denoted as Research Area B. The underlying research hypothesis of the present work is that further significant increases in lift generation of civil aircraft compared to the current state technology are possible using active lift systems. The investigated high-lift concept utilizes a combination of internally blown flaps and circulation control to achieve high flow turning over the wing. A flexible leading edge device for the wing without gap or step is designed to reduce noise generation and to increase the efficiency of the active blowing system. Further, closed-loop control of blowing is envisaged. The overall objective of the project is to design an active lift system that requires a minimum of additional engine power to generate the required lift. A multidisciplinary, collaborative approach is taken, combining the fields of aerodynamics, material science, microtechnology, turbomachinery and electrical engineering to obtain optimum performance of the overall lift generation system. The research progress during the first two years of this ongoing work is presented in this paper. |