| Autor(en) | Heykena, Constance | Friedrichs, Jens |
|---|---|
| Titel | Aerodynamic investigation of an embedded UHBR-engine concept |
| Herausgeber | Proceedings of GPPS Forum 18 Global Power and Propulsion Society, Zurich, 2018 |
| Erscheinungsjahr | 2018 |
| Abstract | To cope with the changing demands in air transport the Collaborative Research Centre (CRC) 880 emphasis future development of technologies for the application on a cruise efficient transport aircraft. The future aviation challenges like the reduction in fuel consumption and noise emission shall be met by a transport aircraft design with short take-off and landing capabilities. Part of this concept is to mount the aircraft propulsion system on the wing aft of its trailing edge. Nacelles mounted over-the-wing cannot only offer benefits in noise reduction due to shield effects by the wing but also have the potential to accommodate aircraft engines with growing engine diameters without any ground clearance restrictions. Moreover, a possible synergy between the wing flowfield and nacelle inlet might lead to a short nacelle design which is crucial for increasing bypass ratios of turbofan engines. Within the presented numerical study, a preliminary design of an embedded Ultra-High-Bypass-Ratio-engine (UHBR) was investigated to evaluate the corresponding flow phenomena for an on-wing-nacelle (OWN) at high speed conditions. The axial position of the engine will be varied at constant lift. The results show that the aircraft performance improves in terms of angle of attack and drag by shifting the nacelle axially downstream. |
| Autor(en) | Heykena, Constance | Friedrichs, Jens | Savoni, Luciana | Rudnik, Ralf |
|---|---|
| Titel | Engine airframe integration sensitivities for a STOL commercial aircraft concept with over-the-wing mounted UHBR-turbofans |
| Herausgeber | Proceedings of Global Power and Propulsion Forum, Montreal, 2018 |
| Erscheinungsjahr | 2018 |
| Abstract | A transport aircraft concept featuring over-the-wing-mounted nacelles (OWN) positioned aft of the wing’s trailing edge is investigated with numerical methods. The objective of the study is to compare two different approaches for integrating the nacelle to the airframe from an aerodynamic point of view. On one hand, a pylon mounted OWN configuration is chosen for installing the propulsion system. On the other hand, a closer coupling between wing and nacelle by embedding the OWN into the wing is examined. Both configurations will be analysed at a representative reference position and discussed in terms of similarities and differences. Afterwards, a positioning study with a free flying nacelle is conducted to explore the aerodynamic sensitivities of wing and nacelle for this engine airframe integration position. The results show that a favourable position with the potential for drag reduction can be found. |
| Autor(en) | Lummer, Markus | Mößner, Michael | Delfs, Jan |
|---|---|
| Titel | Computation and Validiation of Acoustic Shielding at Realistic Aircraft Configurations |
| Herausgeber | AIAA Paper, DOI: 10.2514/6.2018-2823, American Institute of Aeronautics and Astronautics, Aviation 2018, Atlanta, GA |
| Erscheinungsjahr | 2018 |
| Abstract | Acoustic shielding calculations were performed for a generic test object (NACA 0012) and two realistic aircraft configurations, an Unmanned Aerial Vehicle (UAV) and a Hybrid Wing Body (HWB), and compared with experimental data, where the monopole sound source was realized using laser pulses. The agreement between calculation and experiment is good. Due to wind tunnel size limits experimental data are often restricted to the acoustic nearfield and its usability for farfield shielding predictions must be assessed numerically. In the present paper, shielding patterns were defined and its evolution with increasing distance from the geometry was studied using a simple shifting and scaling procedure. For higher frequencies, a linear scaling of the patterns with increasing distance could be established. |
| Autor(en) | Savoni, Luciana | Rudnik, Ralf |
|---|---|
| Titel | Pylon Design for a Short Range Transport Aircraft with Over-the-Wing Mounted UHBR Engines |
| Herausgeber | AIAA 2018-0011, AIAA SciTech Forum, 8–12 January 2018, Kissimmee, FL (USA). |
| Erscheinungsjahr | 2018 |
| Abstract | Over-the-wing mounted (OWM) engines, together with their design challenges and their potential in terms of aerodynamic benefits and positive installation effects, are investigated with CFD methods. The analysed reference configuration is a new concept of a civil transport aircraft with short take-off and landing characteristics featuring a circulation control supported high lift system. The concept is intended to provide extraordinary airfield performance while meeting low noise standards. The reference aircraft will be firstly analysed in its wing/body layout. Successively, engine and pylon will be integrated and analysed. A description of the pylon design and parametrization will be given. The results of the wing/body/engine/pylon configuration computations will be discussed in order to assess the transonic flow phenomena taking place on the upper wing when an engine is integrated over the wing in cruise condition and the overall impact of the pylon on the flowfield. Particular attention will be reserved to the flow on the pylon, in order to identify aerodynamic characterisitscs, possible flow separations and to evaluate a strategy for an optimization process. The pylon optimization procedure will be described in detail, together with the tools used and the parameters defining the pylon shape. The preliminary results and trends of the Design of Experiment will eventually be discussed in order to provide an outlook on complete optimization scenarios for such configurations |
| Autor(en) | Delfs, Jan W. | Appel, Christina | Bernicke, Paul | Blech, Christopher | Blinstrub, Jason | Heykena, Constance | Kumar, Pradeep | Kutscher, Konstantin | Lippitz, Nicolas | Lummer, Markus | Rossian, Lennart | Savoni, Luciana | Delfs, Jan |
|---|---|
| Titel | Aircraft and technology for low noise short take-off and landing |
| Herausgeber | 35th AIAA Applied Aerodynamics Conference |
| Erscheinungsjahr | 2017 |
| Abstract | This paper discusses characteristic multi-disciplinary issues related to quiet short take-off and landing for civil transport aircraft with a typical short to medium range mission. The work reported here is focussing on the noise aspects and is embedded in the collaborative research centre CRC880 in Braunschweig, Germany. This long term aircraft research initiative focusses on a new transport aircraft segment for operation on airports with shorter runway length in commercial air transport. This calls for a community-friendly aircraft designed for operations much closer to the home of its passengers than today. This scenario sets challenging, seemingly contradictory aircraft technology requirements, namely those for extreme lift augmentation at low noise. The Research Centre CRC880 has therefore devised a range of technology projects that aim at significant noise reductions and at the generation of efficient and flexible high lift. The research also addresses flight dynamics of aircraft at takeoff and landing. Two companion papers, reporting about the research in the field of ”Efficient high lift” 1 and ”Flight dynamics” 2 complete the presentation of the CRC880. It is envisaged that in general significant noise reduction -compared to a reference turbofan driven aircraft of year 2000 technology- necessarily requires component noise reduction in combination with a low noise a/c concept. Results are presented from all the acoustics related projects of CRC880 which cover the aeroacoustic simulation of the source noise reduction by flow permeable materials, the characterization, development, manufacturing and operation of (porous) materials especially tailored to aeroacoustics, new UHBR turbofan arrangements for minimum exterior noise due to acoustic shielding as well as the prediction of jet noise vibration excitation of cabin noise by UHBR engines compared to conventional turbofans at cruise. |
| Autor(en) | Savoni, Luciana | Rudnik, Ralf |
|---|---|
| Titel | Aerodynamic Assessment of Pylon-Mounted Over-the-Wing Engine Installations on a STOL Commercial Aircraft Concept |
| Herausgeber | New Results in Numerical and Experimental Fluid Mechanics, Vol. 11, pp 51-60, Springer Verlag, ed. A. Dillmann, et.al. |
| Erscheinungsjahr | 2016 |
| Abstract | Aerodynamic interference effects and potential benefits of an over-the-wing engine installation are examined with CFD methods. The reference configu-ration is a new concept of transport aircraft with STOL capabilities. The wing/body configuration is compared to the wing/body/engine configuration with power-off nacelle. Subsequently, jet-on computations are carried out to address the influence of the jet presence on the engine/airframe interference effects. The engine is initially considered in the reference position. Following this, a position variation of the engine is performed to analyze the interaction with the shock wave generating on the wing. To conclude the study, a preliminary evaluation of the installation drag is done, to investigate the possibility of having a favorable interference effect and reducing drag with respect to more conventional under-the-wing mounted engines installations. |
| Autor(en) | Delfs, Jan | Faßmann, Benjamin | Lippitz, Nicolas | Mößner, Michael | Müller, Lars | Rurkowska, Katherina |
|---|---|
| Titel | SFB 880 – AEROACOUSTIC RESEARCH FOR LOW NOISE TAKE-OFF AND LANDING |
| Herausgeber | CEAS Aeronautical Journal |
| Erscheinungsjahr | 2014 |
| Abstract | This paper gives an overview about prediction capabilities and the development of noise reduction technologies appropriate to reduce high lift noise and propeller noise radiation for future low noise transport aircraft with short take-off and landing capabilities. The work is embedded in the collaborative research centre SFB880 in Braunschweig, Germany. Results are presented from all the acoustics related projects of SFB880 which cover the aeroacoustic simulation of the effect of flow permeable materials, the characterization, development, manufacturing and operation of (porous) materials especially tailored to aeroacoustics, new propeller arrangements for minimum exterior noise due to acoustic shielding as well as the prediction of vibration excitation of aircraft structures, reduced by porous materials. |
| Autor(en) | Müller, Lars |
|---|---|
| Titel | Aerodynamic Performance of an Over-the-wing Propeller Configuration at Increasing Mach Number |
| Herausgeber | CEAS Aeronautical Journal, Vol. 5, No. 3, pp. 305-317 |
| Erscheinungsjahr | 2014 |
| Abstract | Over-the-wing propeller configurations and particularly channel wing concepts show increased climb performance, and through effective acoustic shielding, reduced noise emissions when compared to a conventional tractor configuration. The main aerodynamic mechanisms could be identified by steady flow simulations of a simplified wing geometry and actuator disk. At take-off, 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 ofmagnitude lower. The numerical results give evidence that, even 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 amount of propeller efficiency that is lost through high inflow velocity above the wing increases with Ma due to compressibility effects. As a result, the propulsive efficiency of an over-the-wing configuration is 16 % smaller than the reference (tractor). Semi-empirical correlations showthat even at very lowMach numbers a drawback of at least 5 %remains. Although repositioning the propeller at the wing trailing edge may recover 4 % of the propulsive efficiency atMa = 0.6, it is not advisable to give up most of the noise-shielding effect at take-off which is an important advantage of the channel wing. |
| Autor(en) | Müller, Lars |
|---|---|
| Titel | Unsteady Flow Simulations of an Over-the-Wing Propeller Configuration |
| Herausgeber | 50th AIAA/ASME/SAE/ASEE Joint Propulsion Conference, No. AIAA 2014-3886, Cleveland, Ohio |
| Erscheinungsjahr | 2014 |
| Abstract | The aerodynamic integration effects of an embedded over-the-wing propeller at take-off conditions are discussed based on steady and unsteady Reynolds-averaged Navier-Stokes flow simulations. In contrast to the rotating blade and hub geometry, the steady computations utilized an actuator disk model with blade element theory enhancement to investigate the mutual influnce between installed propeller and wing with sufficient accuracy. A simplified high-lift geometry of this channel wing concept is compared to a conventional tractor configuration. While the general overthe- wing integration effects, such as lift-to-drag ratio improvement and deteriorated propeller efficiency, are already captured by inexpensive steady simulations, only unsteady computations with full propeller geometry reveal some important flow details. The most striking unsteady effect is the interaction of the blade tip vortex with the boundary layer of the wing which only occurs at the channel wing due to the close coupling. As a consequence the low momentum fluid detaches above the flap leading to a comparatively low lift coefficient. |
| Autor(en) | Müller, Lars | Heinze, Wolfgang | Kozulovic, Dragan | Hepperle, Martin | Radespiel, Rolf |
|---|---|
| Titel | Aerodynamic Installation Effects of an Over-the-Wing Propeller on a High-Lift Configuration |
| Herausgeber | J. Aircraft, Vol. 51, No. 1, pp. 249-258, 2014 |
| Erscheinungsjahr | 2014 |
| Abstract | Preliminary design studies indicate that a cruise-efficient short takeoff and landing aircraft has enhanced takeoff performance at competitive direct operating costs when using high-speed propellers in combination with internally blown flaps. The original tractor configuration is compared to an over-the-wing propeller, which allows for noise shielding. An additional geometry with partially embedded rotor similar to a channel wing is considered to increase the beneficial interaction. This paper shows the aerodynamic integration effects with a focus on climb performance and provides an assessment of the three aforementioned configurations for a simplified wing segment at takeoff conditions. Steady Reynolds-averaged Navier–Stokes simulations have been conducted using an actuator disk model and were evaluated based on the overall design. Interacting with the blown flap, the conventional tractor propeller induces large lift and drag increments due to the vectored sliptream. Although this effect is much smaller for an over-the-wing configuration, by halving the lift augmentation, the lift-to-drag ratio and the propulsive efficiency are considerably improved. Besides a moderate lift gain, the main advantage of a channel wing design is the location of the thrust vector close to the center of gravity resulting in a smaller nosedown pitching moment due to thrust. A disadvantage of over-the-wing propellers is the inhomogeneous inflow at higher velocity, which leads to oscillating blade loads and reduced efficiency. |
| Autor(en) | Müller, Lars | Kozulovic, Dragan | Friedrichs, Jens |
|---|---|
| Titel | Unsteady Flow Simulations of an Over-the-wing Propeller Configuration |
| Herausgeber | Proceedings of 50th AIAA/ASME/SAE/ASEE Joint Propulsion Conference, Cleveland |
| Erscheinungsjahr | 2014 |
| Abstract | The aerodynamic integration effects of an embedded over-the-wing propeller at take-off conditions are discussed based on steady and unsteady Reynolds-averaged Navier-Stokes flow simulations. In contrast to the rotating blade and hub geometry, the steady computations utilized an actuator disk model with blade element theory enhancement to investigate the mutual influnce between installed propeller and wing with sufficient accuracy. A simplified high-lift geometry of this channel wing concept is compared to a conventional tractor configuration. While the general over-the-wing integration effects, such as lift-to-drag ratio improvement and deteriorated propeller efficiency, are already captured by inexpensive steady simulations, only unsteady computations with full propeller geometry reveal some important flow details. The most striking unsteady effect is the interaction of the blade tip vortex with the boundary layer of the wing which only occurs at the channel wing due to the close coupling. As a consequence the low momentum fluid detaches above the flap leading to a comparatively low lift coefficient. |
| Autor(en) | Müller, Lars | Kozulovic, Dragan | Radespiel, Rolf |
|---|---|
| Titel | Aerodynamic performance of an over-the-wing propeller configuration at increasing Mach number |
| Herausgeber | CEAS Aeronautical Journal DOI 10.1007/s13272-014-0108-1 (online, to be printed soon) |
| Erscheinungsjahr | 2014 |
| Abstract | Over-the-wing propeller configurations and particularly channel wing concepts show increased climb performance, and through effective acoustic shielding, reduced noise emissions when compared to a conventional tractor configuration. The main aerodynamic mechanisms could be identified by steady flow simulations of a simplified wing geometry and actuator disk. At take-off, 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, even 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 amount of propeller efficiency that is lost through high inflow velocity above the wing increases with Ma due to compressibility effects. As a result, the propulsive efficiency of an over-the-wing configuration is 16 % smaller than the reference (tractor). Semi-empirical correlations show that even at very low Mach numbers a drawback of at least 5 % remains. Although repositioning the propeller at the wing trailing edge may recover 4 % of the propulsive efficiency at Ma = 0.6, it is not advisable to give up most of the noise-shielding effect at take-off which is an important advantage of the channel wing. |
| Autor(en) | Lummer, Markus | Richter, Christoph | Pröber, Carsten | Delfs, Jan |
|---|---|
| Titel | Validation of a Model for Open Rotor Noise Predictions and Calculation of Shielding Effects using a Fast BEM |
| Herausgeber | AIAA Paper, DOI: 10.2514/6.2013-2096, American Institute of Aeronautics and Astronautics, CEAS/AIAA Aeroacoustics Conference 2013, Berlin |
| Erscheinungsjahr | 2013 |
| Abstract | For application in BEM/FMM shielding calculations a simple analytical model for the loading noise of contra rotating open rotors (CRORs) with different rotational speeds is derived. Following previous work of S.L.A. Glegg, the model is formulated in frequency domain and the pressure is approximated by a set of dipoles on circles on the propeller disk. The dipole strength depends on the blade loading function and can be obtained, e.g., by CFD calculations. For arbitrary rotational speeds, the blade loading function is not a perodic function on the propeller disk anymore and must be approximated, e.g., by a least-squares Fourier approximation. The CROR model is checked against a time domain solution using rotating dipoles and validated with data from a test of Rolls-Royce’s open rotor model rig 145 in DNW. The lowest three and most dominant peaks in the spectrum of the uninstalled rotor are well predicted by the method with errors less than 3dB with a correct directivity. For higher frequencies larger errors are observed. The CROR model has been developed for shielding calculations with the DLR BEM/FMM code. Some information about the code is given and the applicability of the model is demonstrated for a CROR installed at a modified DLR F6 aircraft geometry |
| 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) | Müller, Lars | Kozulovic, Dragan | Hepperle, Martin | Radespiel, Rolf |
|---|---|
| Titel | Installation Effects of a Propeller Over a Wing with Internally Blown Flaps |
| Herausgeber | Proc. of the 30th AIAA Applied Aerodynamics Conference, No. AIAA 2012-3335, New Orleans, LA (USA) |
| Erscheinungsjahr | 2012 |
| Abstract | Aiming at maximum climb performance, the lift-to-drag ratio and the installed thrust of a STOL transport aircraft can be enhanced through a synergistic propeller integration. Reynolds- Averaged-Navier-Stokes simulations have been conducted on a generic geometry to quantify the aerodynamic interactions between the propulsion system and a wing with blown flaps. At takeo , a conventional tractor configuration shows a distinct thrust vectoring e ect inducing large lift and drag increments. By relocating the propeller at midchord above the wing, the lift over drag ratio and the installed eciency are considerably improved while losing half of the lift augmentation. Compared to a simple over-the-wing installation, a channel wing design with a partially embedded propeller has the advantage that the thrust vector is closer to the center of gravity resulting in a smaller pitching moment due to thrust. An issue of over-the-wing propellers is the inhomogeneous inflow to the propeller which leads to cyclic variations in blade load and reduced net thrust. |
| Autor(en) | Müller, Lars | Kozulovic, Dragan | Hepperle, Martin | Radespiel, Rolf |
|---|---|
| Titel | The Influence of the Propeller Position on the Aerodynamics of a Channel Wing |
| Herausgeber | Proc. of 61. Deutscher Luft- und Raumfahrtkongress, No. DLRK 2012-281259, Berlin (Germany) |
| Erscheinungsjahr | 2012 |
| Abstract | The paper investigates a generic channel wing configuration regarding the aerodynamic sensitivities to design parameters. Numerical simulations include a variation of the channel depth, the chordwise position of the propeller and clearance for the simplified wing and actuator disk geometry. Evaluation of the lift-to-drag ratio of the wing and the propeller efficiency indicate complex dependencies between geometric parameters and aerodynamic performance. It is evident that a highly integrated design with large embedding depth and minimum gap size leads to most beneficial influences on the wing but an adverse effect on the propeller. As the propulsion system always suffers from this kind of installation, the mutual influence is not of synergistic nature. Evaluating a corrected lift-to-drag ratio which takes the thrust loss on the actuator disk into account, the figure of merit of the overall configuration is only little affected by the three design parameters. More specifically, a less close coupling is considered advantageous when aiming at high climb angles. Together with the expected shielding capabilities, a small noise footprint at take-off can be indirectly achieved through aerodynamically driven measures. |