Patent GB-1341241-A (GB)
Title: Power plants for the jet propulsion of aircraft
IPC: F02K5/00
Filed: 1971-01-11
Abstract: 1341241 Homopolar machines; MHD power plant SOC NATIONALE D'ETUDE ET DE CONSTRUCTION DE MOTEURS D'AVIATION 11 Jan 1971 [15 Jan 1970] 1159/71 Heading H2A [Also in Division F1] An aircraft jet propulsion plant comprises at least one mechanical compressor for compressing a flow of gas, heating or combustion means for raising the compressed gas flow to a high temperature and a jet pipe through which the gas flow escapes to atmosphere, at least part of the energy for driving the compressor being taken from the high temperature gas flow, at least under certain conditions of operation, by means of an MHD generator, the conversion channel of which, carrying the gas flow, is located downstream of the heating or combustion means. In the embodiment shown in Fig. 9, a compressor 501a, 501b, 501c is followed by a combustion chamber 602, a turbine 601, a combustion chamber 502 and an MHD generator 503 having a superconducting field winding. At take-off and at low speeds, the compressor elements 501a, 501b, 501c are driven mainly by homopolar electric motors 505b connected in series or, as shown, in parallel to a homopolar generator 605 driven by the turbine 601 and having a superconducting field winding. At high speeds, the compressor elements are driven mainly or wholly by homopolar electric motors 505a connected in series to the electrodes 508, 509 of the MHD generator, and the turbine may then act as a compressor. The relative contributions of the two generators 503, 605 are controlled by varying their respective field currents. Instead of separate motors 505a, 505b, a single motor for each compressor element may be provided, the generator driven by the turbine then being connected in parallel with the MHD generator. The connection between the turbine and the compressor may instead be a mechanical one. The turbine and the combustion chamber may be omitted. As shown in Fig. 10, the homopolar motors 505a, 505b have a common superconducting field winding 525. Each motor 505a comprises three rotating discs and three stationary discs interconnected by contacts each preferably formed by a ring of liquid metal, as described in Specification 1160/71. The motors 505a are connected to the MHD generator by annular conductors 511, 512, the latter being formed partly by a stator of the turbine 601. Each motor 505b comprises a single rotating disc connected to annular conductors 611, 612 by annular liquid metal contacts, the conductor 612 being branched off to the motors 505b (not shown) via compressor stator rings 513c. The armature 624 of the homopolar generator driven by the turbine is integral with the turbine-rotor 619 and is connected to the conductors 611, 612 by annular liquid metal contacts 627a, 627b. Two superconducting field windings 625a, 625b carrying currents in the same sense form a substantially axial magnetic field in the region of a disc-like portion 624b of the armature 624. Another superconducting field winding 625c carrying current in the opposite direction forms, in conjunction with the windings 625a, 625b, a substantially radial magnetic field in the region of a cylindrical portion 624a of the armature 624. The compressor may comprise a series of contra-rotating, blade rings each having a disc which forms the armature of an individual homopolar motor as described in Specification 1,340,363.