Patent GB-813247-A (GB)
Title: Improvements in gas turbine engines
IPC: F02C3/10
Filed: 1957-01-16
Abstract: 813,247. Gas-turbine plant. GENERAL MOTORS CORPORATION. Jan. 16, 1957 [Jan. 16, 1956], No. 1628/57. Class 110 (3). [Also in Group XII] A gas-turbine engine comprising a compressor supplying air to a combustion chamber feeding a turbine driving and coaxial with the compressor and a separate coaxial power turbine has a rotary thermal regenerator drum mountedto rotate about an axis transverse to the turbine shafts for heating the combustion air by the turbine exhaust gases, the turbine casings and combustion chamber lying within the eircurit. ference of the drum which is contained in a plenum chamber divided by a bulkhead. The bulkhead in which the turbine casings are fixed, separates the high and low pressure sides of the regenerator drum. The invention is described with reference to an automobile gas turbine comprising a centrifugal compressor 47, Fig. 3, feeding air through a diffuser 54 and one part of drum-shaped rotary regenerator matrices 14 to four combustion chambers 16, Fig. 3a. The combustion products are supplied to a turbine 89 which drives the compressor 47 and are then passed to a further turbine 147 which drives the output shaft 350, Fig. 3b, through reduction gearing 120. The turbine 147 exhausts through an annular diffuser 18 and another part of the matrices 14 into two exhaust collectors 19, each of which is provided with a main exhaust outlet and an auxiliary exhaust outlet 21. The matrices 14 rotate about an axis perpendicular to the shaft 60 connecting the turbine 89 and compressor 47 and parallel to the axes of the combustion chambers. The auxiliaries such as fuel pump, tachometer generator are mounted on a casing 10 and are driven from the compressor through a shaft 71, bevel gears 74, 76 and gearing 81. A removable cover-plate 82 provides access to the gearing. The shaft 60 which is stiffened by a sleeve 88, is mounted in a ball-bearing 61 and a roller bearing 86 both of which are supported by the engine frame 53. The outer case of the engine, which serves as the regenerator housing, consists of a sheet metal front cover 94 which is circular in cross-section at the forward end and rectangular at the rear end. The rear flanges of this cover are fixed to the top and bottom of the bulkhead 13 by bolts 96. The side bolting flange 97 of the front cover is arcuate, being disposed outside the margin of the regenerator drums 14 to provide the forward edge of openings through which the drums may be installed and removed. The rear edge of this opening is defined by outside flanges on the exhaust collectors 19. An approximately circular regenerator cover 99 is bolted on to these flanges. This cover comprises a plate 101 having two openings. The forward opening 102 is normally covered by a combustion chamber cover 103. A light metal plate 109 welded to plate 101 covers the rear opening. The rear of the engine between the exhaust collectors 19 is closed by a rear cover 111. A radiationshield 122 which is generally co-extensive with the regenerator cover and spaced outwardly from it, is mounted on each side of the engine. A rear radiation shield 126 is provided to reduce the heat radiated from the exhaust collectors 19 to the reduction gear 120. This shield comprises side plates 127 parallel to and spaced from the inside walls of the exhaust collectors and a central portion which is similar shape to the rear turbine cover 111. The turbine 19, Fig. 3a, comprises an outer casing formed by the parts 136, 137, 138. The part 136 extends through the bulkhead 13 and is secured thereto by bolts 139. The power turbine wheel 137 is bolted to the output shaft 170 which is supported in a cylindrical cartridge 171 by bearings 173, 176. The cartridge 171 is mounted in the reduction gear case 120. A heat shield 184 is disposed between a sealing ring 183 and a portion 159 of the exhaust duct and the face of the turbine wheel 147. Cooling air from the compressor is supplied to the passage 186 and discharged into the space between the seal ring and heat shield 184 from which it flows through holes 187 on to the turbine wheel disc. There are two horizontal combustion chambers 16 on each side through which gas flows inwardly towards the centre of the engine. The combustion chambers comprise a number of rings 191 joined together by corrugated spacing strips. The discharge end of each combustion chamber fits slidably into one of two entrances 193 provided in a transition section 194 leading to a semi-annular discharge section 196. Ignition plugs inserted obliquely into the combustion chamber dome locate the chamber axially. Dilution air openings 202 are provided in the last ring of the combustion chamber and in the entrance portions of the transition sections. Tubes 201 interconnect the combustion chambers. The straps 203 between the entrance portions 193 locate the transition sections 194. The straps 203 have a notch 204 which is received between abutments on a tie bolt 206 threaded into the wall of frame 53. Clips 207 prevent displacement of the straps. The tiebolt 206 also reinforces the combustion chamber cover 103 against gas pressure. The engine frame 53 is shielded from the heat of the hot air by a heat shield which comprises a metal sleeve 211 and a blanket of heat-insulating material 212 within the sleeve. This shield is spaced from the frame 53 to provide an air passage 214 through which unheated air from the compressor is led to holes 216, 217 in the turbine inner shroud support and thence to the rim of the compressor turbine wheel. A plate 220 welded to the sleeve 211 closes the gap between the two regenerator matrices 14. Each regenerator matrix 14 comprises porous heatexchange material 230 between end rings 231 which are provided with gear rings 232 by means of which the matrices are rotated by hydraulic motors. Each of the matrices is supported by four rollers 233 mounted on upper and lower shafts 234, 236. Shaft 234 also carries two driving gears. The bulkhead 13 comprises a central plate 251 which carries above and below the plate two seal bar assemblies 252 which extend from side to side of the engine and from the upper and lower margins of the plate to the top and bottom of the housing. Each seal-bar assembly comprises an inner seal bar 253, a central block 254 and an outer seal bar 256. The block 254 closes the space between the two regenerator drums 14, which extend through the bulkhead on each side between the bars 253, 256. The outside ends of the seal bars are connected by removable end caps 258 to permit installation or removal of the matrices 14. Four main seals 260 are provided to prevent leakage of air from the high pressure side to the low pressure side of the bulkhead. These seals carry rollers 261 which ride on the rim 231 of the matrix and have trunnions 262 which may move radially in slots 263 in the block 254 and slots 264 in the end caps 258. Rim seals formed by graphite sealing segments 268 resiliently loaded by coil springs 269 are also provided. An exhaust pipe 21 running to the rear of the vehicle is of sufficient area to carry the exhaust gases without excessive back pressure when the engine is idling. A main exhaust of larger area in each exhaust collector is closed under idling conditions by a number of spring-loaded overlapping louvres. These lourves may be opened by a power cylinder when the throttle pedal is depressed to increase the fuel supply to the engine. The loading of the spring on the louvres is such that any significant gas pressure will hold the louvres open so that they remain open even when the throttle is closed until the engine has decelerated to its idling speed. The power cylinder may, if desired, be dispensed with. The engine is supported in the chassis by a support 83, Fig. 3, at the inlet of the compressor and by a transverse beam attached to the rear face of the reduction gear case, the extremities of the beam being suitably supported on the chassis. Specifications 813,248, 813,249 and 813,250, [all in Group XIII], are referred to.