GB971223A - Gas turbine power plant - Google Patents

Abstract

971,223. Jet propulsion plant. ROLLS-ROYCE Ltd. Dec. 17, 1962, No. 47629/62. Heading F1J. A gas turbine jet propulsion engine of the by-pass type comprises an air intake passage, compressor means, main combustion equipment, turbine means and reheat combustion equipment, there being a by-pass duct through which a part of the air compressed in the compressor means may by-pass the main combustion equipment and the turbine means and pass into the main gas flow duct upstream of the reheat combustion equipment through one or more openings, means being provided for varying the effective area of the one or more openings. A supplementary air duct is provided and is arranged to receive ram air from the air intake passage and to pass the air to the by-pass duct with which it communicates by way of a valve device. A first embodiment is similar to the embodiment described with reference to Fig. 2 of Specification 971,222 except that in the present case a rotatably-mounted vane 30 is disposed at the outlet of each shoot 37 by which the bypass duct communicates with the main gas flow duct. The plant shown in Fig. 2 comprises a low pressure compressor 46 and a low pressure turbine 51 mounted on a common shaft, a high pressure compressor 48 and a high pressure turbine 50 mounted on a common shaft, main combustion equipment 49 and reheat combustion equipment 52. A part of the air from the low pressure compressor may pass through the by-pass duct 55 and through the outlet shoots 57 into the main gas flow downstream of the turbines 50, 51 but upstream of the reheat equipment 52. The outlet shoots have associated therewith control members 58 which are movable between the two positions indicated in full lines and in broken lines. For by-pass operation the members 58 are disposed in the position of minimum area indicated by full lines. The compressors 46, 48 are provided with adjustable inlet guide vanes 45 and 47 respectively. The plant comprises also a supplementary air duct 43 which communicates at its upstream end with the air intake duct 42 and at its downstream end with the by-pass duct 55 by way of openings controlled by a valve member 61. The upstream end of the supplementary air duct is provided with adjustable vanes 54 which may be positioned either to permit or to prevent flow through the duct. The plant may be operated as a ram jet engine by closing the compressor inlet guide vanes 45 and 47, opening the vanes 54 of the supplementary air duct, opening the valve member 61 whereby ram air may flow from the supplementary air duct 43 to the by-pass duct 55, moving the control members 58 to the maximum area positions and bringing the reheat combustion equipment 52 into operation. In Fig. 3, pivoted flap members 33a are provided adjacent the downstream end of the supplementary air duct 13a, the flap members being positioned as shown in full lines when the plant is operating as a by-pass engine so that part of the air from the low pressure compressor may pass to the by-pass duct 32a and flow through the supplementary air duct is prevented. When operating as a ram jet engine the flap members 33a are moved to the positions indicated in broken lines so that ram air can pass through the supplementary air duct 13a to the by-pass duct 32a and so to the reheat combustion equipment. The intake of the low pressure compressor 16a is closed by the flap members 66 and the intake to the high pressure compressor 18a is closed by the adjustable guide vanes 17a during this phase of operation. Specification 971,221 also is referred to.