Fluid reaction surfaces (i.e. – impellers) – Rotor having flow confining or deflecting web – shroud or... – Radially extending web or end plate
Patent
1987-09-01
1989-01-03
Powell, Jr., Everette A.
Fluid reaction surfaces (i.e., impellers)
Rotor having flow confining or deflecting web, shroud or...
Radially extending web or end plate
416223B, F04D 2922
Patent
active
047953110
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to compressor building and, more particularly, to centrifugal compressor impellers.
BACKGROUND OF THE INVENTION
Known in the art is the impeller of a centrifugal compressor comprising the main disc, blades and a covering disc which consists of a web to effect gas flow in the impeller and a ring to accomodate seals (V.F. Ris. Centrifugal Compressor Machines, 1981, Mashinostroenie Publishers, Leningrad, pp. 35, 103).
The covering disc is made solid from one forging. The impellers with such covering discs feature the possibility of operation at high circumferential velocities (from 120 to 300 m/s).
However, the making of covering discs solid from one forging calls for substantial consumption of metal (metal utilization factor is 15%) and great labour intensity (85% of metal turn into chips).
Besides, high circumferential velocities give rise to flexural strain of the ring and the web, as well as radial strain of the ring. These strains bring about radial movement of the ring which calls for larger clearances between the ring and the seals mounted in the compressor body. The larger the clearances, the greater are gas leakages and the lower is the compressor efficiency.
There is known in the art a centrifugal compressor impeller, comprising the main disc, blades and a covering disc made up from the web for effecting the flow of gas in the impeller and the ring for accomodating the seals, both the web and ring being interconnected. (cf. A. D. Bruk. Smoke Exhausters of Gas Purification Facilities. 1984, Machinostroenie Publishers, Moscow, p. 120).
The ring is connected to the web either through welding or rivetting. The impeller in which the covering disc is made composite with such a connection of the web to the ring features lesser labour and metal intensity compared with that in which the disc is solid, but higher stress in the web-ring joint making it impossible to use such impellers in case circumferential velocities are greater than 120 m/s.
SUMMARY OF THE INVENTION
It is the main object of the present invention to develop an impeller wherein the web is linked with the ring so as to diminish the stress in the place of connection and thereby make it possible to use these impellers for circumferential velocities of over 120 m/s.
The object set forth is accomplished in the centrifugal compressor impeller, comprising the main disc, blades and the covering disc which consists of the interconnected web to effect gas flow in the impeller and the ring to accomodate seals, in which, according to the invention, the web-ring joint is detachable to form mated surfaces in the web and ring and has an annular shoulder on the mated surface of the ring as viewed from the blades, said shoulder being accomodated in the annular groove made on the mated surface of the web whose internal diameter is less than the ring diameter along the mated surfaces by 1 to 1.5.times.10.sup.-3 Do, where Do is the web internal diameter.
It is only the centrifugal force from the inherent mass of the covering disc web and the part of the blades' mass that affects the web. The force of interaction between the web and the ring is actually absent because no interaction is observed between the ring and the web with the chosen difference of diameters (tension value), these elements merely contact each other. The lack of a bending moment rules out the bending of the web thereby ensuring its steady loading and, as a result, the lowering of the level of circumferential stresses and a complete elimination of radial stresses. Besides, the ring of the covering disc is acted upon only by the centrifugal forces of the inherent mass of the ring, therefore, stresses therein and consequently, radial motions are negligible.
The absence of the forces of interaction between the web and the ring, and a low stress level in the place of connection of the web with the ring make it possible to use such a construction of the impellers with the covering discs operating at circumferential velocities substantially surpass
REFERENCES:
patent: 1902406 (1933-03-01), Inokuty et al.
patent: 1983201 (1934-12-01), Van Rijswijk
patent: 2285266 (1942-06-01), Fullemann
patent: 2392858 (1946-01-01), McMahan
patent: 2613609 (1952-10-01), Buchi
patent: 2784936 (1957-03-01), Schmidt
patent: 4720242 (1988-01-01), Lovisetto
V. F. Ris. Centrifugal Compressor Machines, 1981, Mashinostroenie Publishers, Leningrad, pp. 35, 103.
A. D. Bruk Smoke Exhausters of Gas Purification Facilities, 1984, Machinostroenie Publishers, Moscow, p. 120.
Arkhipov Vladimir V.
Levin Yakov S.
Magdychansky Vadim S.
Petrov Gennady I.
Raer Gilya A.
Powell Jr. Everette A.
Proizvodstvennoe Obiedinenie "Nevsky Zavod" Imeni V.I. Lenina
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