| Autor(en) | Giesecke, Daniel | Friedrichs, Jens |
|---|---|
| Titel | Aerodynamic Comparison Between Circumferential and Wing-Embedded Inlet Distortion for an Ultra-High Bypass Ratio Fan Stage |
| Herausgeber | Proceedings of the ASME Turbo Expo 2019: Turbomachinery Technical Conference and Exposition. Volume 2A: Turbomachinery. Phoenix, Arizona, USA |
| Erscheinungsjahr | 2019 |
| Abstract | Future aircraft design concepts often show a somewhat wing embedded ultra-high bypass ratio engine. The aircraft concept of the Coordinated Research Centre 880 (CRC880) is a single-aisle configuration with engines partly integrated over the aircraft wing. The aircraft is designed to take off and land on regional airfields with low noise and fuel emissions to address the guidelines set by the ACARE. As a result of the engine installation, the inlet induces a non-axisymmetric boundary layer ingestion into the fan stage. In experimental setups, inlet distortion has often been seen as a 60-degree circumferential inlet stagnation pressure distortion. However, the fan stage inlet flow of the prescribed engine installation of the CRC880 differs to a great extent from a 60-degree sector. In this paper, an aerodynamic comparison between a realistic inflow situation and a similar 60-degree inlet distortion for the same ultra-high bypass ratio fan stage is given. The realistic inflow situation is a result of the flow moving over the aircraft wing suction side and entering the nacelle. As non-axisymmetric inlet geometry remains the same for both cases, therefore, only the total pressure boundary condition at nacelle inlet was changed between both cases. Hence, full annulus simulations are required. Both inlet distortion cases are equivalent by matching average 60-degree distortion coefficient. This study points out that the method, by using averaged 60-degree segment values, excludes specific inflow characteristics. For the same averaged 60-degree distortion coefficient, the local distortion of the embedded case is up to four times larger at rotor tip compared to the segmental approach. For constant mass flow, fan pressure ratio and isentropic efficiency drop by more than five and eight percent respectively. At peak efficiency operating condition, the decrease is even more significant with more than nine percent in stage efficiency. For future embedded aircraft engine configurations, the fan designer has to take into account the non-axisymmetric local flow changes. Hence, the 60-degree segment method is not sufficient when investigating experimental boundary layer ingesting fans and therefore, further method developments are necessary. |
| Autor(en) | Giesecke, Daniel | Bullert, Marcel | Friedrichs, Jens | Stark, Udo |
|---|---|
| Titel | Optimization of High Subsonic, High Reynolds Number Axial Compressor Airfoil Sections for Increased Operating Range |
| Herausgeber | Proceedings of the Global Power & Propulsion Society (GPPS) Forum, Montreal, Canada, 2018 |
| Erscheinungsjahr | 2018 |
| Abstract | In this paper an increase of up to 4 % in surge margin while having more than a one percent increase in peak isentropic efficiency for an optimized stator of a high subsonic axial compressor was achieved. Using a simplified design method coupled with an optimization algorithm, only stacked stator spanwise blade elements were optimized and remaining the same rotor. Subsonic axial compressor can be exposed to different inflow situations along blade height with circumferential changes. In the present study, the optimization of each airfoil section is done by only varying three main parameters, which reduces computational time. The chosen approach combines a generalized parabolic arc mean camber with the so-called Class Function / Shape Function Methodology. The comparison to the original stator airfoil sections shows an increase in operating range of up to 22 % with 33 % lower minimum losses. A stator only investigation confirms the increased performance for all optimized airfoil sections. |
| Autor(en) | Giesecke, Daniel | Lehmler, Marcel | Friedrichs, Jens | Blinstrub, Jason | Bertsch, Lothar | Heinze, Wolfgang |
|---|---|
| Titel | Evaluation of ultra-high bypass ratio engines for an over-wing aircraft configuration |
| Herausgeber | Journal of the Global Power and Propulsion Society, 2, 493–515 |
| Erscheinungsjahr | 2018 |
| Abstract | Today, main hub airports are already at their capacity limit and hence, smaller airports have become more interesting for providing point-to-point connections. Unfortunately, the use of regional airports induces an increased environmental footprint for the population living around it. In an attempt to solve the related problems, the research project Coordinated Research Centre 880 aims to examine the fundamentals of a single-aisle aircraft with active high-lift configuration powered by two geared ultra-high bypass turbofan engines mounted over the wing. Low direct operating costs, noise shielding due to the over-wing configuration, and short runway lengths are the main advantages. Highlighting the performance, economical and noise benefits of a geared ultra-high bypass engine is the key aim of this paper. This assessment includes a correspondingly adjusted aircraft. Open literature values are applied to design the two investigated bypass ratios, a reference engine with a bypass ratio of 5 and 17 respectively. This study shows that a careful selection of engine mass flow, turbine entry temperature and overall pressure ratio determines the desirable bypass ratio. The aircraft direct operating costs drop by 5.7% when comparing the designed conventional with a future ultra-high bypass ratio engine. Furthermore, the sound at source for a selected mission and operating condition can be reduced by 7 dB. A variable bypass nozzle area for the ultra-high bypass ratio engine is analysed in terms of performance and operability. An increase of safety margin is shown for the turbofan engine with a variable bypass nozzle. It is concluded that this unconventional aircraft configuration with ultra-high bypass ratio engines mounted over the wing has the potential to relieve main hub airports and reduce the environmental impact. |
| 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) | Atalayer, Caglar | Friedrichs, Jens | Wulff, Detlev |
|---|---|
| Titel | Aerodynamic Investigation of S-Duct Intake for High Power Turboprop Installed on a Channel Wing |
| Herausgeber | The Aeronautical Journal, 121(1242), pp. 1131-1146 |
| Erscheinungsjahr | 2017 |
| Abstract | Installation effects on the S-duct intakes of a high power turboprop were investigated by comparing three different nacelle configurations as the channel wing, over-the-wing and conventional tractor wing using computational fluid dynamic methods. The interaction of the propeller, the wing, and the nacelle on the scoop type turboprop intakes were identified in terms of recovery and distortion on the aerodynamic interface planes. An actuator disc model was used to simulate the propeller downstream effects. The channel wing installation of S-ducts showed approximately 2% higher total pressure recovery than the other configurations. The channel wing configuration with a wrap-around S-duct experienced a 2% lower circumferential distortion intensity, whereas over-the-wing had an increase by 3% in comparison to the tractor wing. It was also observed that the S-duct type had a greater influence on the radial distortion intensity than the installation type. The swirl coefficient distribution showed that multiple peaks occurred as opposed to swirl results based on a single sector of the aerodynamic interface plane. The difference between swirl peaks of shaft penetration S-duct was reduced by 14% when installed on channel wing, whereas the peaks of wrap-around experienced 90° phase shift, and their difference showed 10% increase on channel wing. |
| Autor(en) | Atalayer, Caglar | Friedrichs, Jens | Wulff, Detlev |
|---|---|
| Titel | Installation Effects on Highly Loaded Turboprop S-Duct Intake Proximity |
| Herausgeber | ASME Turbo Expo 2017: Turbomachinery Technical Conference and Exposition |
| Erscheinungsjahr | 2017 |
| Abstract | S-duct intake of a highly loaded turboprop installed on a channel wing was investigated for the interaction effects using computational fluid dynamics. Performance effects on the aerodynamic interface plane (AIP) were compared for varying the intake proximity to propeller mid-plane and nacelle hub. A wrap-around intake with a length aspect ratio of L/D = 3 was used for the analysis. Propeller slipstream was approximated with an actuator disc model. Steady-state RANS simulations was run for cruise condition. The performance was analysed in terms of total pressure recovery and distortion coefficients on AIP. Circumferential and radial distortion intensity descriptors were used along with standard coefficients for the distortion levels. Gain in total pressure recovery was achieved when the intake distance to nacelle hub was increased, whereas it was decreased with farther distance to actuator disc. The larger gap between the nacelle hub and the S-duct intake increased both the distortion coefficient and circumferential intensity on the AIP, as opposed to the decrease in radial distortion intensity. A different trend was observed for the intakes closest to the actuator disc, which showed higher recovery, experienced lower distortion except in radial direction. Analysis of the swirl distortion coefficient on the intake AIP revealed multiple peaks along the circumference. The comparison of maximum positive peaks confirmed a decrease with increasing distance to nacelle hub as the radial distortion intensity. The negative swirl peak comparison revealed an increase with increasing distance to nacelle hub, similar to distortion coefficient. The results will serve as guidelines for the S-duct intake design process and its integration into highly loaded turboprop nacelle of the high-lift aircraft. |
| Autor(en) | Atalayer, Caglar | Friedrichs, Jens | Wulff, Detlev |
|---|---|
| Titel | Aerodynamic Performance Comparison Of High Power Turboprop S-Duct Intake On Channel Wing At Varying Azimuth |
| Herausgeber | 12th European Conference on Turbomachinery Fluid Dynamics & Thermodynamics ETC12, Stockholm, Sweden |
| Erscheinungsjahr | 2017 |
| Abstract | S-duct intake component for a highly loaded turboprop engine was investigated considering its installation on a channel wing of an active high-lift aircraft using computational fluid dynamics. The objective is to observe the interaction effects of the propeller-nacelle-wing on the S-duct intake aerodynamics, especially when the intake is positioned at different azimuth angles with respect to rotation axis. Single scoop wrap-around type S-duct was integrated into a representative nacelle body. The propeller was modeled as an actuator disc for the slipstream effects. Steady-state Reynolds-averaged Navier-Stokes simulations were run using negative Spalart-Allmaras turbulence model. Although the results showed that the reference S-duct position at phi=270° had the relatively higher recovery than the other variations, significant improvements in total pressure distortion and intensities were achieved at phi=0° and 90° positions. Up to 3% decrease in swirl coefficient levels was observed when the wrap-around S-duct was positioned at phi=90° in comparison to reference position. |
| Autor(en) | Giesecke, Daniel | Atalayer, Caglar | Müller, Thomas | Friedrichs, Jens | Hennings, Holger |
|---|---|
| Titel | Investigation of Intake and Propulsion System for High-Lift Aircraft |
| Herausgeber | SFB 880 - Fundamentals of high-lift for future commercial aircraft: Biennial Report, 2017 |
| Erscheinungsjahr | 2017 |
| Abstract | The propulsion system plays the significant role in achieving the objectives of CRC 880 for active high-lift. Two different engine types are investigated for the CRC 880 aircraft: highly loaded turboprop with a channel wing installation, and a geared ultra-high bypass ratio turbofan mounted over the wing. In the case of turboprop, the aerodynamic interaction between its intake duct and the channel wing flow dictates the engine integration strategy. The main objective is to design an S-duct intake considering its aerodynamic performance. The ultra-high bypass ratio turbofan is investigated for its high performance and favorable effect on direct operating costs. Furthermore, it is mounted over the wing to reduce the noise emissions. From a rotor dynamic perspective, a larger diameter and a modified rotational speed due to the gearbox imply various types of coupling frequencies with the aircraft wing. An engine installed over wing changes the fan inflow and therefore, distortion effects needs to be assessed. The preliminary work of the described topics are covered in this report. |
| Autor(en) | Giesecke, Daniel | Friedrichs, Jens | Stark, Udo |
|---|---|
| Titel | Preliminary Aerodynamic Design of a Fan Stage for an Ultra High Bypass Ratio Engine |
| Herausgeber | 23rd International Society of Air-breathing Engines (ISABE) Conference, Manchester, UK, 2017 |
| Erscheinungsjahr | 2017 |
| Abstract | In the framework of the Coordinated Research Centre 880 (Sonderforschungsbereich 880) the fundamentals of an environmental friendly future regional aircraft are being developed. Therefore, an engine with a bypass ratio of 17 for the target reference aircraft mission has to be designed resulting in an increased propulsive effciency. In order to reduce the adverse viscous drag effects of a large intake for such ultra high bypass ratio engines, the intake will be reduced in its length. With this background, the engine installation position was chosen above the wing to realize some noise shielding effects as well as inflow straightening effects. To investigate the inflow situation and interaction a suitable transonic fan stage has to be developed. The paper describes the design process starting from aircraft specifications to an engine performance model and a preliminary fan stage design. The preliminary fan stage design procedure relies on the isentropic imple-radial equilibrium equation. The blade sections are parabolic mean lines with cubic thickness distributions. During the design process special attention has been drawn on the supersonic flow approaching the rotor leading edge resulting in a complex shock structure. The shock structure goes hand-in-hand with the incidence chosen. Firstly, a peak isentropic effciency of 87 percent was achieved with a large in- and outlet duct. Secondly, numerical simulations using isolated nacelle flow by cutting away the inlet duct show an increase in isentropic effciency to almost 88 percent at design point. To summarize, numerical verifications show consistent results with the design specification and hence, methodology used. Further inflow investigations in case of the on-wing mounted engine will be part of the on-going research project. |
| Autor(en) | Giesecke, Daniel | Stark, Udo | Harms Garcia, Rubén | Friedrichs, Jens |
|---|---|
| Titel | Design and Optimization of Compressor Airfoils by Using Class Function / Shape Function Methodology |
| Herausgeber | 17th International Symposium on Transport Phenomena and Dynamics of Rotating Machinery (ISROMAC), Maui, USA, 2017 |
| Erscheinungsjahr | 2017 |
| Abstract | This paper describes a new design method for high Reynolds number subsonic compressor blade sections for industrial gas turbines and compressors. The focus is on the middle and end stages, where the Reynolds numbers are about 2 to 6×10^6 and the Mach numbers between 0.4 and 0.8. The new design method combines i) a parametric geometry definition method, ii) a fast blade-to-blade flow solver, and iii) an optimization tool with a suitable objective function. The development of a new blade section is based on a conventional NACA-65 design, subsequently modified to an optimized CSM profile, where CSM means Class Function / Shape Function Methodology. The new profile shapes are obtained by superimposing a camber line and a thickness distribution. Both the camber line and the thickness distribution are prescribed as analytical functions to cut down the CPU-time for geometry set up and to guarantee smooth geometries. Numerical calculations are performed by applying the two-dimensional blade-to-blade solver MISES. The optimization method used in this paper is the single-objective genetic algorithm (SOGA) from the DAKOTA library. The objective function consists of 5 components and takes into account the whole loss polar. The corresponding computing time is relatively short - that is 1 to 2 days. At high Reynolds number, the new profiles show decreased design point losses and increased operating limits compared to corresponding results using conventional NACA-65 profiles. In addition, the present results show close agreement with those produced by so-called high performance profiles of the relevant literature. |
| 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) | Müller, Thomas | Giesecke, Daniel | Friedrichs, Jens | Hennings, Holger |
|---|---|
| Titel | Thermodynamic and Rotordynamic Assessment of Conventional and Ultra-High Bypass Ratio Engines |
| Herausgeber | 17th International Symposium on Transport Phenomena and Dynamics of Rotating Machinery (ISROMAC), Maui, USA, 2017 |
| Erscheinungsjahr | 2017 |
| Abstract | Due to the economical aspiration to increase the efficiency and several ecological regulations to reduce CO2 and noise emissions, aircraft and engine manufacturer have to increase the bypass ratio of gas turbines. But, the higher the bypass ratio of a gas turbine is the larger the rotating masses are. Thus, concerning the system stability due to the change of the eigenbehavior of the aircraft in its structure, the dynamic influences of gyroscopic moments as the consequence of the angular momentum of the engine are an uncertainty and need to be investigated carefully. This paper compares two gas turbines, a conventional one with a bypass ratio of 5 and one with an ultra-high bypass ratio of 17. Two different approaches are presented. On the one hand, a comparison regarding the thermodynamical cycle process, on the other hand, using a multibody formulation, a model of a Coanda wing with each of the engines mounted over the airfoil is presented. The analysis conducts the structural coupling and dynamical influences on the wing structure arising during their operation at specific design points. The comparison of the dynamic influences should show which structural effects on the wing structure come along with the trade-off due to increased thermodynamic efficiency. |
| Autor(en) | Müller, Thomas | Hennings, Holger |
|---|---|
| Titel | STRUCTURAL DYNAMIC INFLUENCE OF AN UHBR ENGINE ON A COANDA-WING |
| Herausgeber | IFASD, Como |
| Erscheinungsjahr | 2017 |
| Abstract | Due to the need of higher efficiency and the reduction of CO2 and noise emission the bypass ratio of gas turbines tends to increase. This leads to higher rotational masses which arises the question of gyroscopic moments influencing the eigenbehavior of the aircraft and thus the system stability regarding structural depended phenomena, e.g. flutter. Therefore this paper presents a multibody model to determine the structural coupling between a Coanda wing and an ultra high bypass ratio gas turbine (BPR of 17). The results in form of the spectral analysis of an eigenvalue analysis enables the understanding of the coupling mechanisms and gyroscopic influences. By analyzing the time dependent behavior of the wing-engine system under consid- eration of a follower force, representing the thrust, deepens the understanding of the structural load at the wing root. |
| Autor(en) | Müller, Thomas | Hennings, Holger |
|---|---|
| Titel | Rotordynamic Validation of a Twin Rotor-bearing System Considering Gyroscopic Forces and Bearing Dynamics with a Multibody Formulation: Application to a Geared UHBR Gas Turbine |
| Herausgeber | DLRK, Braunschweig |
| Erscheinungsjahr | 2016 |
| Abstract | A rotordynamic study for an engine with an ultra-high bypass ratio (BPR=17) was performed using a multibody (Simpack) and a finite element (Ansys) description. The previous validation based on an analytical system of a coaxial counter rotating twin rotor model was performed to legitimize the use of Simpack and the methodological approach, which included the modal reduction of finite element bodies and their integration in the multibody description. Therefore the eigenfrequencies as a function of the rotational speed and the unbalance respond due to eccentricity were compared. The same methodology was then applied to the UHBR engine. Performing an evaluation of the critical speed map, Campbell diagram and an unbalance respond analysis to identify the system behavior. By examining the system respond due to an unbalance force the need of a full modal description of the rotating parts with respect to a suspension point of the complete engine was shown. |
| Autor(en) | Atalayer, Caglar | Friedrichs, Jens | Wulff, Detlev |
|---|---|
| Titel | S-Duct Intake Configuration Sensitivity of a Highly Loaded Turboprop by CFD Methods |
| Herausgeber | Proceedings of ASME Turbo Expo 2015: Turbine Technical Conference and Exposition, Montreal, Canada |
| Erscheinungsjahr | 2015 |
| Abstract | Highly-loaded turboprop intake was investigated for two different shaft connection types to assess the configuration sensitivity on performance. Turboprop intakes inherently have S-shape to bend around the gearbox, which have significant effects on the flow. Previous geometric sensitivity analysis on uninstalled, isolated single scoop S-ducts with shaft penetration showed higher recovery and lower distortion trends for long intakes with shorter ducts. The major pressure loss was observed over the bore due to the penetrating shaft. It is expected that changing the configuration to wrap-around will overcome the loss introduced by flow around the bore. The two configurations were compared by varying the S-duct curvatures using computational methods. The results showed an increase in recovery with lower total pressure distortion levels for wrap-around configuration of the same sizes. The gain in the recovery by the configuration change was observed to be similar to the gain when the ducts were shortened. However, wrap-around S-duct suffered from higher swirl distortion than shaft penetration of the same size but these were observed to be lower than the shaft penetration type with short ducts. Distortion intensities showed opposite trends for the two configurations, with wrap-around producing low distortion in circumferential whereas high in radial direction. The results will be used as the basis for the turboprop intake design and its over-the-wing integration on the high-lift aircraft. |
| Autor(en) | Atalayer, Caglar | Friedrichs, Jens | Wulff, Detlev |
|---|---|
| Titel | Sensitivity Analysis of a Highly Loaded Turboprop S-Duct Intake by CFD Methods |
| Herausgeber | 50th AIAA/ASME/SAE/ASEE Joint Propulsion Conference, Cleveland, Ohio, USA, 2014 |
| Erscheinungsjahr | 2014 |
| Abstract | S-duct intake of a high power turboprop with unconventional integration types requires additional design objectives rather than a basic sizing, considering the propeller-wing-nacelle interaction effects. Before the conceptual integration process, sensitivity analysis based on the intake performance has been done to identify the limitations on the S-duct geometry using computational methods. The flow simulations were done on an isolated, uninstalled S-duct intake, excluding propeller effects and particle separator, for an initial specification in advance of the actual sizing. The effects of fundamental geometric features, as the intake aspect ratio, duct lengths and spread angle, were investigated on the flow quality through the aerodynamic interface plane (AIP), quantified by total pressure recovery and distortion. The results show a preference to longer S-ducts whereas the shorter inner ducts are observed to be advantegous for their higher recovery capacities with lower distortion levels. |
| 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. |