Patent GB-587150-A (GB)
Title: Turbine unit
IPC: F02K3/12
Filed: 1943-04-15
Abstract: 587,150. Gas turbines; centrifugal pumps. TURBO ENGINEERING CORPORATION. April 15, 1943, No. 6077. Convention date, April 18, 1942. [Classes 110 (i) and 110 (iii)] [Also in Group XXXIII] In a gas turbine plant for aircraft, a twostage high-pressure turbine 502 drives a power shaft 492 which leads to gearing by which a pair of oppositely-rotating air-screws are driven. A two-stage low-pressure turbine 534 drives a four-stage centrifugal compressor and the final blading 538 of the turbine is designed to provide a high axial velocity exhaust which passes to a propulsion jet 550. Air passes to the compressor through a chamber 55<1>, Fig. 12B, and is passed through a cooler 600 between the second and third stages. Streamlined annular guides 564 are located in the pump return passages. Air from the compressor is conducted by the pipe 592 to a vertical combustion chamber 598 and passes through guide vanes 594 just before the position of the burners. The products of combustion pass through nozzles 508'to the inward flow blades 506 of the turbine. These blades are followed by fixed blades 510 and axial-flow blades 572. The gases pass by the pipe 527 to a similar low-pressure turbine 530, 532, 536, 538. The turbines are constructed as described in Specification 520,045 and U.S.A. Specifications 1,926,225 and 1,959,703. The first rotor of each turbine is cooled by an air stream in passages 516, 546 which is induced by bladings in those passages. The streams traverse the stationary bladings 510, 536 within annular guides 518, 548 and mix with the working fluid in the bladings 512, 538. In each case, the air is drawn along grooves 498, 542 in the rotor shafts. In addition, air taken round the second stage of the compressor is passed through channels 522, 524 in the first high-pressure rotor. In another plant, the propeller shaft and high-pressure turbine are axially in line with the air compressor and low-pressure turbine. The highpressure turbine has two inward-flow stages and the low-pressure turbine an inward-flow wheel followed by an axial flow stage. The high velocity exhaust passes without diversions through a heat exchanger on its way to a propulsion jet. The compressed air passes through transverse and circumferential pipes of the heat-exchanger and thence to combustion chambers lying parallel with the general axis. In another plant, the high-pressure turbine is one ring only of inward flow blades on an overhung rotor. The combustion chambers are arranged within the pipes by which the gases, being thereby re-heated, pass, in the opposite direction, from the high-pressure turbine to the low-pressure turbine. The latter comprises two back-to-back inward flow stages. In another plant, the high-pressure turbine comprises a pair of contra-rotational wheels ; the first has inward flow and drives the air-screw. The second has axial flow and drives the last two stages of the compressor. The first two compressor stages are driven at a lower speed by a low-pressure turbine having radial flow at the nozzles and a mainly axial flow in the running blades. The compressor delivery is at the forward end and the air passes through pipes which surround the combustion chambers being thereby re-heated to enter the latter at their rear ends. Alternatively, two combustion chambers in the form of single turn helices surround and extend forwardly, of, the highpressure turbine. The compressor shafts are hollow and are cooled by air from the second stage of the compressor. Cooling air from the interstage cooler passes to the propulsion jet. Governing may be effected by a controlled byepass leading air from the compressor delivery back to directing nozzles which admit it radially inwards to the first compressor stage, or, by a controlled extraction of high-pressure air which is used to drive an air turbine on the high-pressure turbine shaft.