The Experts below are selected from a list of 5397 Experts worldwide ranked by ideXlab platform
Ralf Rudnik - One of the best experts on this subject based on the ideXlab platform.
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Investigation and improvement of directional stability and control of a propeller-driven STOL aircraft
CEAS Aeronautical Journal, 2019Co-Authors: Dennis Keller, Ralf RudnikAbstract:The scope of this paper is to investigate and improve the aerodynamic properties of a propeller driven state-of-the-art active high-lift Configuration in lateral motion. 3D RANS simulations of the Landing Configuration with circulation control and slipstream deflection under crosswind, and one engine inoperative (OEI) conditions were performed. The Configuration shows directionally unstable behavior at small sideslip angles and high yawing moment production under OEI conditions. Flowfield analyses indicate that both can be attributed to wake-tail interference effects caused by slipstream–vortex interaction. The integration of tail fences at the rear of the fuselage leads to considerable improvements for both conditions.
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Nacelle Strake Design for Short Takeoff and Landing Configuration with Turboprop Engines
Journal of Aircraft, 2018Co-Authors: Dennis Keller, Yasim Julian Hasan, Ralf RudnikAbstract:The scope of this Paper is to investigate the integration effects of turboprop engines on a high-lift wing with an internally blown plain flap system with Reynolds-averaged Navier–Stokes computatio...
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Investigation and Improvement of Directional Stability and Control under Slipstream Effects
2018 AIAA Aerospace Sciences Meeting, 2018Co-Authors: Dennis Keller, Ralf RudnikAbstract: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 interference effects, caused by slipstream-vortex interaction. The integration of tail fences at the rear of the fuselage leads to considerable improvements under both conditions.
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Numerical investigations of aerodynamic properties of a propeller blown circulation control system on a high wing aircraft
CEAS Aeronautical Journal, 2016Co-Authors: Dennis Keller, Ralf RudnikAbstract: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 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. In addition, 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.
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NACELLE STRAKE DESIGN FOR A SHORT TAKE-OFF AND Landing Configuration WITH TURBOPROPS
2016Co-Authors: Dennis Keller, Ralf Rudnik, Yasim Julian HasanAbstract:The scope of the presentation is to discuss the integration effects of turboprop nacelles on a high-lift wing with an internally blowing plain flap system with Reynolds-Averaged-Navier-Stokes computations. It is shown that the resulting nacelle vortices can significantly reduce the maximum angle of attack and maximum lift coefficient at zero thrust conditions. In order to limit the negative impact, an inboard nacelle strake was designed with the aim of maximizing the lift coefficient of the Landing configuration at zero thrust. To reach this goal, a sensitivity study on basic geometric strake parameters was carried out. The best nacelle strake is able to improve the maximum lift coefficient by 17 lift counts and the maximum angle of attack by three degrees. The study also revealed further potential of improvement due to an outboard strake. Using an outboard strake, which is not properly designed but simply mirrored from the inboard one leads to an additional improvement of 13 lift counts and 4 degrees in maximum angle of attack. Furthermore, it is shown that the installation of an inboard strake does not negatively impact the high-lift performance at a moderate thrust level.
Dennis Keller - One of the best experts on this subject based on the ideXlab platform.
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Investigation and improvement of directional stability and control of a propeller-driven STOL aircraft
CEAS Aeronautical Journal, 2019Co-Authors: Dennis Keller, Ralf RudnikAbstract:The scope of this paper is to investigate and improve the aerodynamic properties of a propeller driven state-of-the-art active high-lift Configuration in lateral motion. 3D RANS simulations of the Landing Configuration with circulation control and slipstream deflection under crosswind, and one engine inoperative (OEI) conditions were performed. The Configuration shows directionally unstable behavior at small sideslip angles and high yawing moment production under OEI conditions. Flowfield analyses indicate that both can be attributed to wake-tail interference effects caused by slipstream–vortex interaction. The integration of tail fences at the rear of the fuselage leads to considerable improvements for both conditions.
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Nacelle Strake Design for Short Takeoff and Landing Configuration with Turboprop Engines
Journal of Aircraft, 2018Co-Authors: Dennis Keller, Yasim Julian Hasan, Ralf RudnikAbstract:The scope of this Paper is to investigate the integration effects of turboprop engines on a high-lift wing with an internally blown plain flap system with Reynolds-averaged Navier–Stokes computatio...
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Investigation and Improvement of Directional Stability and Control under Slipstream Effects
2018 AIAA Aerospace Sciences Meeting, 2018Co-Authors: Dennis Keller, Ralf RudnikAbstract: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 interference effects, caused by slipstream-vortex interaction. The integration of tail fences at the rear of the fuselage leads to considerable improvements under both conditions.
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Numerical investigations of aerodynamic properties of a propeller blown circulation control system on a high wing aircraft
CEAS Aeronautical Journal, 2016Co-Authors: Dennis Keller, Ralf RudnikAbstract: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 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. In addition, 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.
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NACELLE STRAKE DESIGN FOR A SHORT TAKE-OFF AND Landing Configuration WITH TURBOPROPS
2016Co-Authors: Dennis Keller, Ralf Rudnik, Yasim Julian HasanAbstract:The scope of the presentation is to discuss the integration effects of turboprop nacelles on a high-lift wing with an internally blowing plain flap system with Reynolds-Averaged-Navier-Stokes computations. It is shown that the resulting nacelle vortices can significantly reduce the maximum angle of attack and maximum lift coefficient at zero thrust conditions. In order to limit the negative impact, an inboard nacelle strake was designed with the aim of maximizing the lift coefficient of the Landing configuration at zero thrust. To reach this goal, a sensitivity study on basic geometric strake parameters was carried out. The best nacelle strake is able to improve the maximum lift coefficient by 17 lift counts and the maximum angle of attack by three degrees. The study also revealed further potential of improvement due to an outboard strake. Using an outboard strake, which is not properly designed but simply mirrored from the inboard one leads to an additional improvement of 13 lift counts and 4 degrees in maximum angle of attack. Furthermore, it is shown that the installation of an inboard strake does not negatively impact the high-lift performance at a moderate thrust level.
Markus Fischer - One of the best experts on this subject based on the ideXlab platform.
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effect of slat settings gap and overlap on slat noise based on a test vortex injected upstream of the slat hook
AIAA CEAS Aeroacoustics Conference, 2006Co-Authors: Rolf Emunds, Markus FischerAbstract:The noise sources of commercial aircrafts has nowadays to be split in two categories: the first category covers all the noise sources generated by the propulsion unit while the second category is associated with the airframe itself. Based on the development of high-bypass low noise turbofan engines the contribution of airframe noise in approach and Landing Configuration is enhanced and thus is playing a growing role in aircraft design. On modern civil transport aircraft during approach and Landing airframe and propulsion noise are approximately of the same order of magnitude, hence airframe noise is becoming an increasingly important parameter in the design of civil transport aircraft. The high-lift devices, i.e. the slat trailing edge portion and the flap sidewalls as well as the Landing gear are the main contributors to the airframe noise during take-off and Landing. This paper presents the results of a Computational Aeroacoustics (CAA) analysis for a 2D high-lift pr ofile as part of the Airbus strategy for low-noise high-lift design. The current activities concentrate on slat noise variations due to different slat settings (slat-wing gap (radius of maximum circle to be prescribed between slat pressure side and wing suction side) and slat-wing overlap size (horizontal distance between slat upper trailing edge and wing leading edge) at the design angle of attack. The investigation is based on the vortex injection method that injects a single test vortex at a unique relative position close to the slat hook into a steady state flow field coming from CFD. Beside the changes of the acoustic response due to slat setting variations, complete aerodynamic lift-polars (Cl-α) have been computed for all different slat settings allowing judging also on the aerodynamic impact (i.e. the lift to drag ratio) of such geometrical variations.
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effect of re number ma number and angle of attack on slat noise based on a test vortex injected upstream of the slat hook
AIAA CEAS Aeroacoustics Conference, 2005Co-Authors: Rolf Emunds, Markus FischerAbstract:The noise sources of commercial aircrafts may be split in two categories: the first category covers all the noise generated by the propulsion unit while the second category is associated with the airframe itself. Based on the development of high-bypass low noise turbofan engines the contribution of airframe noise in approach and Landing Configuration is enhanced, thus playing a growing role in aircraft design. The high-lift devices, especially the upper slat trailing edge portion and the flap sidewalls as well as the Landing gear are the main contributors to the airframe noise during take-off and Landing. This paper presents the results of a Computational Aeroacoustics (CAA) analysis for a 2D high-lift profile as part of the Airbus strategy for low-noise high-lift design. Previous, primarily experimental [1,2,3], research activities have shown that the slat (also in conjunction with the main wing leading edge) is one of the major contributors to high-lift airframe noise. With focus on the slat, especially the pressure side (cove area) and the upper trailing edge are to be identified as being the primary source of slat noise. Thus, the current activities concentrate on investigating slat noise by injecting a single test-vortex upstream of the slat hook (i.e. the lower slat trailing edge) for different Re-numbers, Ma-numbers and angles of attack into a steady state flow field coming from CFD.
Nasa - One of the best experts on this subject based on the ideXlab platform.
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Proceedings of the 8th Annual Summer Conference: NASA/USRA Advanced Design Program
2019Co-Authors: NasaAbstract:Papers presented at the 8th Annual Summer Conference are categorized as Space Projects and Aeronautics projects. Topics covered include: Systematic Propulsion Optimization Tools (SPOT), Assured Crew Return Vehicle Post Landing Configuration Design and Test, Autonomous Support for Microorganism Research in Space, Bioregenerative System Components for Microgravity, The Extended Mission Rover (EMR), Planetary Surface Exploration MESUR/Autonomous Lunar Rover, Automation of Closed Environments in Space for Human Comfort and Safety, Walking Robot Design, Extraterrestrial Surface Propulsion Systems, The Design of Four Hypersonic Reconnaissance Aircraft, Design of a Refueling Tanker Delivering Liquid Hydrogen, The Design of a Long-Range Megatransport Aircraft, and Solar Powered Multipurpose Remotely Powered Aircraft.
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Reusable Reentry Satellite (RRS): Recovery tradeoff study
2019Co-Authors: NasaAbstract:The main objectives of the Recovery Tradeoff Study were as follows: (1) to determine whether a land or water recovery best suits RRS system requirements; (2) what type of terminal recovery system is best suited for the RRS; and (3) what are the recovery access timelines after system Landing. Based on the trade parameters and evaluation criteria used in this study, the land-Landing Configuration has an advantage over the water-Landing Configuration. It is recommended that a land-Landing Configuration be developed assuming WSMR as the Landing site. It is also recommended that natural orbits be used for low inclination missions and any orbit adjustments for Landing site targeting be performed at the end of the mission. Near-integer orbits should be used for high inclination missions and allow orbital decay to precess the ground track over the Landing site range.
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Assured crew return vehicle post Landing Configuration design and test
2019Co-Authors: NasaAbstract:The 1991-1992 senior Mechanical and Aerospace Engineering Design class continued work on the post Landing Configurations for the Assured Crew Return Vehicle (ACRV) and the Emergency Egress Couch (EEC). The ACRV will be permanently docked to Space Station Freedom fulfilling NASA's commitment of Assured Crew Return Capability in the event of an accident or illness aboard Space Station Freedom. The EEC provides medical support and a transportation surface for an incapacitated crew member. The objective of the projects was to give the ACRV Project Office data to feed into their feasibility studies. Four design teams were given the task of developing models with dynamically and geometrically scaled characteristics. Groups one and two combined efforts to design a one-fifth scale model for the Apollo Command Module derivative, an on-board flotation system, and a lift attachment point system. This model was designed to test the feasibility of a rigid flotation and stabilization system and to determine the dynamics associated with lifting the vehicle during retrieval. However, due to priorities, it was not built. Group three designed a one-fifth scale model of the Johnson Space Center (JSC) benchmark Configuration, the Station Crew Return Alternative Module (SCRAM) with a lift attachment point system. This model helped to determine the flotation and lifting characteristics of the SCRAM Configuration. Group four designed a full scale EEC with changeable geometric and geometric and dynamic characteristics. This model provided data on the geometric characteristics of the EEC and on the placement of the CG and moment of inertia. It also gave the helicopter rescue personnel direct input to the feasibility study. Section 1 describes in detail the design of a one-fifth scale model of the Apollo Command Module Derivative (ACMD) ACRV. The objective of the ACMD Configuration Model Team was to use geometric and dynamic constraints to design a one-fifth scale working model of the Apollo Command Module Derivative (ACMD) Configuration with a Lift Attachment Point (LAP) System. This model was required to incorporate a rigidly mounted flotation system and the egress system designed the previous academic year. The LAP system was to be used to determine the dynamic effects of locating the lifting points at different locations on the vehicle. The team was then to build and test the model; however, due to priorities, this did not occur. To better simulate the ACMD after a water Landing, the nose cone section was removed and the deck area exposed. The areas researched during the design process were construction, center of gravity and moment of inertia, and lift attachment points.
Rolf Emunds - One of the best experts on this subject based on the ideXlab platform.
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effect of slat settings gap and overlap on slat noise based on a test vortex injected upstream of the slat hook
AIAA CEAS Aeroacoustics Conference, 2006Co-Authors: Rolf Emunds, Markus FischerAbstract:The noise sources of commercial aircrafts has nowadays to be split in two categories: the first category covers all the noise sources generated by the propulsion unit while the second category is associated with the airframe itself. Based on the development of high-bypass low noise turbofan engines the contribution of airframe noise in approach and Landing Configuration is enhanced and thus is playing a growing role in aircraft design. On modern civil transport aircraft during approach and Landing airframe and propulsion noise are approximately of the same order of magnitude, hence airframe noise is becoming an increasingly important parameter in the design of civil transport aircraft. The high-lift devices, i.e. the slat trailing edge portion and the flap sidewalls as well as the Landing gear are the main contributors to the airframe noise during take-off and Landing. This paper presents the results of a Computational Aeroacoustics (CAA) analysis for a 2D high-lift pr ofile as part of the Airbus strategy for low-noise high-lift design. The current activities concentrate on slat noise variations due to different slat settings (slat-wing gap (radius of maximum circle to be prescribed between slat pressure side and wing suction side) and slat-wing overlap size (horizontal distance between slat upper trailing edge and wing leading edge) at the design angle of attack. The investigation is based on the vortex injection method that injects a single test vortex at a unique relative position close to the slat hook into a steady state flow field coming from CFD. Beside the changes of the acoustic response due to slat setting variations, complete aerodynamic lift-polars (Cl-α) have been computed for all different slat settings allowing judging also on the aerodynamic impact (i.e. the lift to drag ratio) of such geometrical variations.
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effect of re number ma number and angle of attack on slat noise based on a test vortex injected upstream of the slat hook
AIAA CEAS Aeroacoustics Conference, 2005Co-Authors: Rolf Emunds, Markus FischerAbstract:The noise sources of commercial aircrafts may be split in two categories: the first category covers all the noise generated by the propulsion unit while the second category is associated with the airframe itself. Based on the development of high-bypass low noise turbofan engines the contribution of airframe noise in approach and Landing Configuration is enhanced, thus playing a growing role in aircraft design. The high-lift devices, especially the upper slat trailing edge portion and the flap sidewalls as well as the Landing gear are the main contributors to the airframe noise during take-off and Landing. This paper presents the results of a Computational Aeroacoustics (CAA) analysis for a 2D high-lift profile as part of the Airbus strategy for low-noise high-lift design. Previous, primarily experimental [1,2,3], research activities have shown that the slat (also in conjunction with the main wing leading edge) is one of the major contributors to high-lift airframe noise. With focus on the slat, especially the pressure side (cove area) and the upper trailing edge are to be identified as being the primary source of slat noise. Thus, the current activities concentrate on investigating slat noise by injecting a single test-vortex upstream of the slat hook (i.e. the lower slat trailing edge) for different Re-numbers, Ma-numbers and angles of attack into a steady state flow field coming from CFD.
