|Title of Invention||
"AN IMPROVED IMPELLER FOR CENTRIFUGAL COMPRESSORS"
|Abstract||An improved impeller for centrifugal compressor to prevent leakage of fluid, comprising a plurality of vanes (3) in between back and front shroudes (4,5); and a casing wall (6), said impeller being secured to a rotatable shaft of said compressor and thereon to a motor, characterized in that a plurality of barrier vanes (7) being formed on an outer circumference of said front shrouds (5) extending into a clearnace gap between said front shroud (5) and said casing wall (6) of said impeller.|
|Full Text||This invention relates an improved impeller for
The impeller and the diffuser used in a centrifugal compressors play an important drop acheiving the desired pressure ratinq stage. The impeller are kown in the art and comprises a plurality of vanes fined to the hub surface and rotated against a stationary shroud surface and which constitute an open type impeller. In the closed type impeller the vanes a fixed in between the hub abd shroud parts and shruud becomes a rotatinq part m this type. The main disadvantage associated with the conventional impellers is that the fluid jet/stream issuing from the rotating impeller while passing into the diffuser is effected, by the leakagae of flow that takes place across the tap of the shroud and passes to the suction side of the impeller. This leakagae flow constitutes the re-circulation loss.
Therefore, the mam object of this invention is to provide an improved impeller which obviates the dasadvantagaes associates with the prior art.
Another object of the invention is to propose an imoeller having means to minimise the leakage of the flow recirculation losses.
According to this invention there is provided an impeler comprising a plurality of vanes having back and front shrouds therewith and adapted to be secured with the rotatable sha^t. characterized in that a plurality of bzarrier vanes being provided which extends out from the outer surface of the front shroud near its periphery into the clearance gap between the front shroud and the casing of the impeller.
In accordance with this invention the impeller comprises impeller vanes having bad- and front shrouds provided therewith and adapted to be disposed in a casing wo.11. Specifically according to this invention, barrier vanes a~e provided on the front shroud outer circumference having clearance space between the impeller front shroud and casing wall of the impeler. The impeller vanes are secured with the rotatable shaft. The barrier vanes are of different shapes such as flat constant thic ness shape, curved type in the form of circular and . cnamfered tube
having an aero foil shape. The orientation of setting of the vanes can be either backward slanted, or radial, or forward slanted. The chord length of the vanes is preferably kept small such that the power consumption is low.
An impeller according to a preferred embodiment of this invention is herein described and illustrated in the accompanying drawings wherein:— Fig.1 shows the side sectional view of the impeller, and Fig.2 shows the front sectional view of the impeller.
Referring to the drawings an impeller i has an impeller vanes 3 secured to a shaft 3A. The impeller 1 is disposed in a casing wall 6. The impeller 3 has a back shroud 4 and front shroud 5 provided therewith. These features are as such known in the art do not constitute inventive features of the present invention. Specifically.according to the present invention parrier vanes 7 are provided on the outer circumference of the front shroude 5 in a spaced relationship with the casing wall 6. The vanes are of different shapes for example flat constant thickness type, curved typed in the form of circular arc, g|$
either backward slanted, or radial slanter, or forward slanted. The chord length of vanes is kept small to feeo the power consumption level low. The height of the vanes extending m the axial direction is also kept low and can be limited to the a;iial spacing width between the shroud and casino wall or taken to be eaqal to a traction of the impeller tip width to reeo the power consumption as low as possible.
The height o1 the vanes (7) in the arial direction can be closely equal to the gap width between the front shrouds (4.5) and the casing wall (6) or it can slightly extend into the casing wall (6) with under-cuts provided in t^e c
1. An improved impeller for centrifugal comaressor to orevent leakage of fluid, comprising a plurality of vanes (3) in between back and front shraudes (4,5); and a casing wall (6). said impeller being secured to a rotatable shaft of said compressor and thereon to a motor, characterized in that a plurality of barrier vanes (7) being formed on an outer circumference of said front shrouds (5) extending into a clearnace gap between said front shroud (5) and said casing wall (6) of said impeller.
2. The impeller as claimed in claim 1 wherein said darner vanes (7) comprises a straight or curved vanes, a curved profile vanes of constant or variable thichness. the curve vanes in the form of a circular arc. cambered type of vanes, or vanes having an aero foil shape.
3. The impeller as claimed in claims 1 and 2. wherein said vanes are oriented either backward or slanted or radial slanted. or forward slanted at an angle with respect to the radia. direction.
4. The impeller as claimed in claim 3 wherein a length of said
vane (7) is smaller than the diameter of said impeller, a height
of said vane (7) is eaual to an a;:ial gap width between said
front shroud (5) and said casino wall (6).
5. The impeller as claimed in any of the preceding claims wherein a plurality of undercut is provided in said casino wall (6) at a corresponding location to a path of said barrier vanes (7) to maintain a running clearance.
|Indian Patent Application Number||114/DEL/1996|
|PG Journal Number||21/2004|
|Date of Filing||17-Jan-1996|
|Name of Patentee||BHARAT HEAVY ELECTRICALS LTD,|
|Applicant Address||BHEL HOUSE, SIRI FORT, NEW DELHI 110 049, INDIA.|
|PCT International Classification Number||F04D 17/08|
|PCT International Application Number||N/A|
|PCT International Filing date|