HTS machines as enabling technology for all-electric airborne vehicles

Masson, Philippe; Brown, Gerald V.; Soban, Danielle; Luongo, C.A.

doi:10.1088/0953-2048/20/8/005

Cited by 108 publications

(59 citation statements)

References 9 publications

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“…The higher performance machines are intended for military applications, but prototypes for commercial machines are beginning to appear. High temperature superconducting (HTS) machines for aircraft propulsion have previously been discussed, primarily with "tube-and-wing" aircraft in mind [7,12].…”

Section: A Superconducting Generators Motors and Transmission Linesmentioning

confidence: 99%

Turboelectric Distributed Propulsion Engine Cycle Analysis for Hybrid-Wing-Body Aircraft

Felder¹,

Kim²,

Brown³

2009

47th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition

241

285

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Meeting NASA's N+3 goals requires a fundamental shift in approach to aircraft and engine design. Material and design improvements allow higher pressure and higher temperature core engines which improve the thermal efficiency. Propulsive efficiency, the other half of the overall efficiency equation, however, is largely determined by the fan pressure ratio (FPR). Lower FPR increases propulsive efficiency, but also dramatically reduces fan shaft speed through the combination of larger diameter fans and reduced fan tip speed limits. The result is that below an FPR of 1.5 the maximum fan shaft speed makes direct drive turbines problematic. However, it is the low pressure ratio fans that allow the improvement in propulsive efficiency which, along with improvements in thermal efficiency in the core, contributes strongly to meeting the N+3 goals for fuel burn reduction. The lower fan exhaust velocities resulting from lower FPRs are also key to meeting the aircraft noise goals. Adding a gear box to the standard turbofan engine allows acceptable turbine speeds to be maintained. However, development of a 50,000+ hp gearbox required by fans in a large twin engine transport aircraft presents an extreme technical challenge, therefore another approach is needed. This paper presents a propulsion system which transmits power from the turbine to the fan electrically rather than mechanically. Recent and anticipated advances in high temperature superconducting generators, motors, and power lines offer the possibility that such devices can be used to transmit turbine power in aircraft without an excessive weight penalty. Moving to such a power transmission system does more than provide better matching between fan and turbine shaft speeds. The relative ease with which electrical power can be distributed throughout the aircraft opens up numerous other possibilities for new aircraft and propulsion configurations and modes of operation. This paper discusses a number of these new possibilities. The Boeing N2 hybrid-wing-body (HWB) is used as a baseline aircraft for this study. The two pylon mounted conventional turbofans are replaced by two wing-tip mounted turboshaft engines, each driving a superconducting generator. Both generators feed a common electrical bus which distributes power to an array of superconducting motor-driven fans in a continuous nacelle centered along the trailing edge of the upper surface of the wing-body. A key finding was that traditional inlet performance methodology has to be modified when most of the air entering the inlet is boundary layer air. A very thorough and detailed propulsion/airframe integration (PAI) analysis is required at the very beginning of the design process since embedded engine inlet performance must be based on conditions at the inlet lip rather than freestream conditions. Examination of a range of fan pressure ratios yielded a minimum Thrust-specific-fuel-consumption (TSFC) at the aerodynamic design point of the vehicle (31,000 ft /Mach 0.8) between 1.3 and 1.35 FPR. We deduced that this wa...

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Section: A Superconducting Generators Motors and Transmission Linesmentioning

confidence: 99%

Turboelectric Distributed Propulsion Engine Cycle Analysis for Hybrid-Wing-Body Aircraft

Felder¹,

Kim²,

Brown³

2009

47th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition

241

285

View full text Add to dashboard Cite

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“…[1][2][3][4][5][6] is an important step forward to obtain large, but lightweight superconducting bulks, which will be important for several applications like the all-electric plane [7] or applications in space [8,9]. Metallic foams also play an important role as shock-absorbers etc.…”

Section: Introductionmentioning

confidence: 99%

Analysis of the microstructure of superconducting YBCO foams by means of AFM and EBSD

et al. 2014

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YBa 2 Cu 3 O y (YBCO) foam samples show an open, porous foam structure, which may have benefits for many applications of high-T c superconductors. As the basic material of these foams is a pseudo-single crystalline material with the directional growth initiated by a seed crystal similar to standard melt-textured samples, the texture of YBCO is a very important parameter. Therefore, we analysed the local texture and grain orientation of the individual struts forming the foam by means of atomic force microscopy (AFM) and electron backscatter diffraction (EBSD). Due to the processing route starting with Y 2 BaCuO 5 (211), a two-phase analysis must be performed, so a high surface quality is necessary to enable an automated EBSD scan. Good quality Kikuchi patterns were obtained from both the YBCO and 211 phases. We found an inhomogeneous distribution of the residual 211 particles, which are mainly randomly oriented and have sizes ranging between 200 nm and 15 µm. In contrast to this, the YBCO matrix shows a dominating orientation with cracks with a typical distance of 1-10 µm. Furthermore, the analysis of strut cross-sections reveals that the entire strut is converted to the YBCO phase.

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“…The electrically driven propulsion system is feasible only if the electrical motors can be about the same size as, or smaller than, existing gas turbines. FIGURE 2 shows a comparison of power densities for electric motors and aircraft engines taken from data by Masson, et al [3]. The values shown in this figure represent general trends, but values for various motors and engines can vary significantly.…”

Section: Introductionmentioning

confidence: 96%

“…At present, most HTS machines use superconductors only in the rotor where DC currents are used to produce a DC magnetic field, which interacts with an AC excitation in the copper stator windings. Designs for allsuperconducting machines show typical power densities as high as 40 kW/kg for rotational speeds of about 10,000 rpm [3]. The use of HTS wire in the stator armature winding leads to significant AC losses in present YBCO materials.…”

Section: Introductionmentioning

confidence: 99%

Cryocoolers for aircraft superconducting generators and motors

Radebaugh

2012

AIP Conference Proceedings

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The proposal by NASA to use high-temperature superconducting (HTS) generators and motors on future (∼2035) aircraft for turboelectric propulsion imposes difficult requirements for cryocoolers. Net refrigeration powers of about 5 kW to 10 kW at 50 K to 65 K are needed for this application. A 2010 survey by Ladner of published work between 1999 and 2009 on existing Stirling and Stirling-type pulse tube cryocoolers showed efficiencies in the range of 10 to 20 % of Carnot at 50 K, much less than the 30 % of Carnot needed to make the concept feasible. A cryocooler specific mass less than about 3 kg/kW of input power is required to keep the cryocooler mass somewhat less than the mass of the superconducting machinery. Current cryocoolers have specific masses about 3 to 10 times this desired value, even for those designed for airborne or space use. We discuss loss and mass sources and make suggestions where improvements can be made. For Stirling and Stirling-type pulse tube cryocoolers, most of the mass is concentrated in the compressor. We show that higher frequency and pressure can have a major influence on reducing the compressor mass. Frequencies up to about 120 Hz and average pressures up to about 5 MPa may significantly reduce the overall cryocooler size and mass while maintaining high efficiency. Other suggestions for reducing the mass are also given.

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HTS machines as enabling technology for all-electric airborne vehicles

Cited by 108 publications

References 9 publications

Turboelectric Distributed Propulsion Engine Cycle Analysis for Hybrid-Wing-Body Aircraft

Turboelectric Distributed Propulsion Engine Cycle Analysis for Hybrid-Wing-Body Aircraft

Analysis of the microstructure of superconducting YBCO foams by means of AFM and EBSD

Cryocoolers for aircraft superconducting generators and motors

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