| Autor(en) | Keller, Dennis | Rudnik, Ralf |
|---|---|
| Titel | Investigation and Improvement of Directional Stability and Control under Slipstream Effects |
| Herausgeber | 2018 AIAA Aerospace Sciences Meeting, Kissimmee, FL, USA, 2018 |
| Erscheinungsjahr | 2018 |
| Abstract | The scope of this paper is to investigate and improve the aerodynamic properties of a propeller driven active high-lift configuration in lateral motion. Therefore, results of 3D RANS simulations of a landing configuration with circulation control and slipstream deflection under crosswind and one engine inoperative (OEI) conditions are discussed. The configuration shows directionally unstable behavior at small sideslip angles and high yawing moment production under OEI conditions. Flowfield analysis indicate that both can be attributed to wake-tail interefence effects, caused by slipstream-vortex interaction. The integration of tail fences at the rear of the fuselage leads to considerable improvements under both conditions. |
| Autor(en) | Savoni, Luciana | Rudnik, Ralf | Ronzheimer, Arno | Heykena, Constance |
|---|---|
| Titel | High Lift Design and Aerodynamic Assessment for an Over-the-Wing Pylon-Mounted Engine Configuration with STOL Capabilities |
| Herausgeber | AIAA 2018-4207 2018 AIAA AVIATION Forum, 25–29 June 2018, Atlanta GA (USA). |
| Erscheinungsjahr | 2018 |
| Abstract | A CFD-based assessment of the low speed high lift performance of over-the-wing mounted engine (OWME) installations for a short range airliner with STOL capabilities is presented in this paper. The main objective of the analysis is to investigate the flow phenomena on the upper surface of the wing in low speed conditions and the interaction between the engine and jet flow and the circulation control supported high lift system. The high lift configuration is characterized by pylon mounted over-the-wing installed UHBR engines, highly deflected Coanda flaps and a specifically designed droopnose at the leading edge of the wing. The study is part of the Collaborative Research Center 880. The design and implementation of the high lift system will be described, together with the numerical approaches and selected results for the considered test cases. The OWME turubofan configuration will be compared to a reference configuration for the same mission with a high wing turboprop configuration. Differences in terms of resulting high lift performance and flow interactions with the different type of engine will be analyzed. Some considerations on the resulting challenges will also be briefly expressed, with the aim of underlining the importance of the low speed mission segment assessment for such configurations. |
| Autor(en) | Diekmann, Jobst Henning | Keller, Dennis | Faez, Edris | Rudnik, Ralf | Gollnick, Volker |
|---|---|
| Titel | Flight mechanics model for spanwise lift and rolling moment distributions of a segmented active high-lift wing |
| Herausgeber | CEAS Aeronautical Journal |
| Erscheinungsjahr | 2017 |
| Abstract | In this study, the aerodynamics of wings using an active high-lift system are investigated. The target is the flight mechanical description of the spanwise forces and resulting moments and the influence of the active high-lift system to their distribution. The high-lift system is a blown flap system divided into six segments per wing. Each segment is assumed to be individually controlled, so the system shall be used for aircraft control and system failure management. This work presents a flight mechanical sub-model for the simulation of flight dynamics, which has been derived from high-fidelity CFD results. An assessment of single-segment blowing system failures will be presented including recommendations for compensation of either lift or rolling moment loss. For this investigation, the compensation is required to act at the same wing side on which the failure appears. Thus, the potential for an increase of system reliability shall be proven. The results show that less performance investment in terms of pressurized air is necessary to compensate the rolling moment of a failing segment instead of its lift. However, large blowing performance increases for the remaining wing segments that occur for some of the failure cases. |
| Autor(en) | Horst, Peter | Sommerwerk, Kay | Neuert, Nora | Krukow, Ian | Keller, Dennis | Diekmann, Jobst | Rang, Joachim | Görtz, Stefan | Krukow, Ian |
|---|---|
| Titel | Flight Dynamics Investigation of an Active High-Lift Aircraft |
| Herausgeber | 35th AIAA Applied Aerodynamics Conference, AIAA AVIATION Forum, Denver, Colorado, 2017 |
| Erscheinungsjahr | 2017 |
| Abstract | The increasing air traffic requires improvements in aircraft design concerning fuel efficiency, noise re- duction, and short take-off and landing (STOL) capabilities. The Sonderforschungsbereich (Coordinated Research Centre) SFB 880 investigates an aircraft with STOL capabilities. The aircraft uses high-pressure air blown through a slot in front of the high lift devices for circulation control. This jet interacts with the boundary layer of the oncoming flow, thus introducing momentum. The increased momentum allows the flow to bend around the flap leading edge due to the Coanda effect. This attached flow, even at very high flap angles of around 65° , results in higher lift coefficients. Consequently, lower approach speeds and shorter runway distances become possible. It is obvious that such aircraft exhibit some unusual characteristics. This paper summarizes some highly interactive results which all end up in a versatile Flight Dynamics model, which allows to investigate the behavior of such aircraft. |
| Autor(en) | Keller, Dennis |
|---|---|
| Titel | High-Lift Design for a Forward Swept Natural Laminar Flow Wing |
| Herausgeber | Deutscher Luft- und Raumfahrtkongress, München, 2017 |
| Erscheinungsjahr | 2017 |
| Abstract | The scope of the paper is to present the results of a RANS based aerodynamic high-lift design for a natural laminar flow wing with negative sweep. The chosen high-lift system consists of a Krueger leading edge flap with shielding function and a fixed-vane trailing edge flap. The design was first optimized in two main wing sections and then verified by 3D RANS siumlations of a wing-body model. Finally, engines were added to the geometric model in order to estimate the high-lift performance of the landing configuration. With a maximum lift coefficient of CL = 2.85 for the wing-body model with engine, the target from the preliminary aircraft design was reached. Further potential for improvement was found in the optimization strategy and the shape of the fuselage-wing junction. |
| Autor(en) | Keller, Dennis | Rudnik, Ralf |
|---|---|
| Titel | Aerodynamic Assessment of Potential Rudder Force Augmentation due to Circulation Control based on a VTP Rudder Design for a STOL Aircraft |
| Herausgeber | Campus Forschungsflughafen, Vol. 14, pp. 141-150 |
| Erscheinungsjahr | 2017 |
| Abstract | The scope of the paper is to assess the potential of using circulation control at the vertical tail plane in order to increase the maximum rudder side force. Therefore, a numerical study on the rudder design is carried out, consisting of a 2D sensitivity study, an estimation of the 3D forces and moments via lifting line method, and a verification by 3D Reynolds-averaged Navier-Stokes (RANS) simulations. Compared to the baseline rudder, the lifting line method yields a 138% increase of the rudder yawing moment due to the use of circulation control. 3D RANS simulations verify the lifting line results. The deviation between yawing moments from the RANS computations and the lifting line method is less than 11%. |
| Autor(en) | Keller, Dennis | Rudnik, Ralf |
|---|---|
| Titel | NUMERICAL INVESTIGATIONS OF AERODYNAMIC PROPERTIES OF A PROPELLER BLOWN CIRCULATION CONTROL SYSTEM ON A HIGH WING AIRCRAFT |
| Herausgeber | CEAS Aeronautical Journal, Vol. 7, Springer, pp. 441–454, 2016 |
| Erscheinungsjahr | 2016 |
| Abstract | The contribution gives an overview over a wide range of CFD simulations, which were performed in the course of the German collaborative research center 880 in order to investigate the aerodynamic properties of a complete turboprop powered transport aircraft in landing configuration with a circulation control high-lift system. The main purpose of the contribution is to highlight aerodynamic and flight mechanical aspects of the integration of lift augmentation technologies into the design of a short take-off and landing aircraft concept. In this context, the influence of engine nacelles and thrust on the stall behavior and the following improvements due to the use of a nacelle strake are discussed. Furthermore, static longitudinal and lateral stability as well as the dynamic longitudinal stability are investigated. While circulation control itself has a rather small impact on the stability, the impact of engine thrust in conjunction with circulation control is considerable. Additionally, the one engine inoperative case was simulated. For some flow and engine conditions, the resulting yawing moments are more than twice as high as the actual yawing moments due to asymmetric thrust. |
| Autor(en) | Keller, Dennis | Rudnik, Ralf |
|---|---|
| Titel | Integration Aspects of Lift Augmentation Systems on the Aerodynamics of a High-Lift Configuration |
| Herausgeber | Campus Forschungsflughafen Forschungsbericht, Vol. 15, No. 4, pp. 145-156, 2015 |
| Erscheinungsjahr | 2015 |
| Abstract | The scope of this report is to illustrate the installation effects of circulation control and turboprop engines on the stability characteristics of the reference aircraft's landing configuration in lateral motion and in failure cases. Therfore, RANS simulations of the full configuration at different side slip angles and with asymmetric boundary conditions of the circulation control system and the propellers were performed. It is shown that the lateral stability of the investigated configuration is influenced by both aspects. While thrust generally leads to a reduced stability, activated circulation control tends to amplify the aircraft's behavior. As a result, the configuration is unstable under certain conditions. The simulation of the one engine inoperative case demonstrated yawing moments up to twice as high as the actual yawing moments due to the asymmetric thrust. Furthermore, the report highlights the impact of the design update on the aerodynamic behavior in longitudinal motion, where an increase of maximum angle of attack and maximum lift could be achieved. Additional configuration enhancements were realized due to the design and integration of a nacelle strake. |
| Autor(en) | Keller, Dennis | Rudnik, Ralf |
|---|---|
| Titel | Numerical Investigations of Aerodynamic Properties of a Propeller Blown Circulation Control System on a High Wing Aircraft |
| Herausgeber | 50th 3AF International Conference on Applied Aerodynamics, Toulouse, 29.3.-1.4.2015 |
| Erscheinungsjahr | 2015 |
| Abstract | The contribution gives an overview over the wide range of CFD simulations, which were performed in the course of the German collaborative research center 880 in order to investigate the aerodynamic properties of a complete aircraft landing configuration with a circulation control high-lift system and turboprop engines. The main purpose is to highlight the integration aspects of lift augmentation technologies into the design of a short take-off and landing aircraft concept. Therefore, the influence of engine nacelles and thrust on the stall behavior and the following improvements due to the use of a nacelle strake are discussed. Furthermore, static longitudinal and lateral stability as well as the dynamic longitudinal stability are investigated. While circulation control itself has a rather small impact, the impact of engine thrust in conjunction with circulation control is considerable. Additionally, the one engine inoperative case was simulated. For some flow and engine conditions, the resulting yawing moments are more than twice as high as the actual yawing moments due to asymmetric thrust and thus are higher than expected. |
| Autor(en) | Keller, Dennis | Rudnik, Ralf |
|---|---|
| Titel | Numerical Investigation of the Dynamic Behavior of a High Lift Configuration with Circulation Control |
| Herausgeber | AIAA 33rd Applied Aerodynamics Conference, Dallas, TX, USA, 2015 |
| Erscheinungsjahr | 2015 |
| Abstract | The scope of this paper is to demonstrate the feasibility of a numerical evaluation of dynamic derivatives of a 3D high-lift configuration. Furthermore, the influence of active lift augmentation systems on the longitudinal dynamic derivatives shall be illustrated. Therefore, forced pitching and plunging motions at different boundary conditions were simulated. The investigation started with a comprehensive sensitivity study regarding algorithmic and configurational parameters on a representative 2D-model. The results show the impact of frequency, amplitude, flap deflection and blowing coefficient. Based on the preliminary 2D study, boundary conditions were selected for the simulation of the entire aircraft in landing configuration. The dynamic derivatives were successfully evaluated based on the linearization method. Neither thrust, nor blowing showed significant impact on the longitudinal dynamic derivatives. |
| Autor(en) | Keller, Dennis | Rudnik, Ralf |
|---|---|
| Titel | Numerical Investigation of Engine Effects on a Transport Aircraft with Circulation Control |
| Herausgeber | Journal of Aircraft, Vol. 52, pp. 421-438, 2015 |
| Erscheinungsjahr | 2015 |
| Abstract | The scope of this paper is to illustrate the installation effects of a turboprop engine on a high-lift configuration of a short take off and landing (STOL) aircraft with circulation control. In addition to the influence on the wing performance, the impact on the longitudinal static stability of the aircraft is also investigated. Furthermore, critical failure cases, namely extit{one engine inoperative} (OEI), as well as an asymmetric circulation control failure, are assessed. Therefore, steady CFD calculations based on the Reynolds-averaged Navier-Stokes (RANS) equations were performed. The propeller is modeled with an actuator disk approach. The results show strong potential of increasing lift by synergy effects between circulation control and propeller slipstream. However, the longitudinal stability and controllability are adversely affected. Regarding the case of OEI, the resulting yawing moments are twice as high as the actual yawing moments from the asymmetric thrust and therefore higher than expected. |
| Autor(en) | Keller, Dennis | Rudnik, Ralf |
|---|---|
| Titel | Numerical Investigations of Aerodynamic Properties of a Propeller Blown Circulation Control System on a High Wing Aircraft |
| Herausgeber | 50th 3AF International Conference on Applied Aerodynamics, Toulouse, 29.3.-1.4.2015 |
| Erscheinungsjahr | 2015 |
| Abstract | The contribution gives an overview over the wide range of CFD simulations, which were performed in the course of the German collaborative research center 880 in order to investigate the aerodynamic properties of a complete aircraft landing configuration with a circulation control high-lift system and turboprop engines. The main purpose is to highlight the integration aspects of lift augmentation technologies into the design of a short take-off and landing aircraft concept. Therefore, the influence of engine nacelles and thrust on the stall behavior and the following improvements due to the use of a nacelle strake are discussed. Furthermore, static longitudinal and lateral stability as well as the dynamic longitudinal stability are investigated. While circulation control itself has a rather small impact, the impact of engine thrust in conjunction with circulation control is considerable. Additionally, the one engine inoperative case was simulated. For some flow and engine conditions, the resulting yawing moments are more than twice as high as the actual yawing moments due to asymmetric thrust and thus are higher than expected. |
| Autor(en) | Keller, Dennis |
|---|---|
| Titel | Numerical Approach Aspects for the Investigation of the Longitudinal Static Stability of a Transport Aircraft with Circulation Control |
| Herausgeber | New Results in Numerical and Experimental Fluid Mechanics IX, 4629 |
| Erscheinungsjahr | 2014 |
| Abstract | The aim of the investigation is to gain more certainty about the approach to evaluate the longitudinal stability and controllability of a high-lift configuration of a transport aircraft with circulation control. Since the work was carried out with a CFD RANS approach, a comprehensive meshing study was performed in advance. |
| Autor(en) | Horst, Peter | Keller, Dennis | Diekmann, Jobst Henning | Krukow, Ian | Sommerwerk, Kay |
|---|---|
| Titel | SFB880: Flight Dynamics |
| Herausgeber | Deutscher Luft- und Raumfahrtkongress, Stuttgart, 2013 |
| Erscheinungsjahr | 2013 |
| Abstract | The paper summarizes approaches and first results on flight dynamics of the Collaborative Research Centre SFB 880 - "Fundamentals of High Lift for Future Commercial Aircraft" - , i.e. high fidelity solutions of dynamics in aerodynamics, aeroelasticity and flight control. |
| Autor(en) | Keller, Dennis | Rudnik, Ralf |
|---|---|
| Titel | Numerical Investigation of Engine Effects on the Stability and Controllability of a Transport Aircraft with Circulation Control |
| Herausgeber | AIAA Applied Aerodynamics, San Diego, 2013 |
| Erscheinungsjahr | 2013 |
| Abstract | The scope of this paper is to illustrate the installation effects of a turboprop engine on a high-lift configuration of a short take off and landing (STOL) aircraft with circulation control. In addition to the influence on the wing performance, the impact on the longitudinal static stability of the whole aircraft is also investigated. Furthermore, critical failure cases, namely one engine inoperative (OEI), as well as an asymmetric circulation control failure are assessed. Therefore, CFD calculations based on the Reynolds-averaged Navier-Stokes (RANS) equations were performed, whereas the propeller is modeled with an actuator disk. |