FR2498679A2 - TURBINE CASE GROOVED CIRCONFERENTIALLY - Google Patents

Abstract

TURBINE CASING SURROUNDING A ROTOR WITH SEVERAL FINS, THE ENDS OF WHICH ARE ADJACENT TO THE CASING, THESE CASING INCLUDING SEVERAL GROOVES EXTENDING CIRCUMFERENTIALLY AT THE END OF THE FINS, ACCORDING TO CLAIM 1 OF THE MAIN PATENT THAT THE MAIN FEATURES 6 ARE IN THIS RELATION BETWEEN THEIR DEPTH D AND THE THICKNESS OF THE THICKEST PART OF THE TIP OF THE FINS IS LESS THAN UNIT. ALSO PREFERREDLY, THEY ARE INCLINED WITH RESPECT TO THE RADIAL PLANE X PERPENDICULAR TO THE AXIS OF THE TURBINE AND TOWARDS THE FLUID FLOW INLET AT AN ANGLE BETWEEN 10 AND 40, PREFERREDLY BETWEEN 20 AND 30.

Description

Circumferentially grooved turbine housing.

  The main patent relates to a turbine casing surrounding a multi-fin rotor whose ends

  adjacent to the casing, the latter being in particular constituting

  killed to form several grooves extending circumferentially

  ferrentially at the ends of the fins and intended to reduce

  leakage flow of the fluid at the end of the fins.

  The purpose of this Certificate of Addition is to specify various provisions relating to these grooves which have also been found to be favorable to obtaining a

better efficiency of the turbine.

  Essentially, these arrangements are as follows - said grooves are such that the ratio between their depth and the thickness of the thickest part of the

  tip of the fins must be less than unity.

  Said grooves must be inclined relative to the radial plane perpendicular to the axis of the turbine and towards the fluid flow inlet, by an angle of between 10

  and 401, preferably between 20 and 301.

  These and other main features will appear

  in the following description of an illustrative embodiment

  trative of the invention, with reference to the accompanying drawing, in which: FIG. 1 is a partial axial sectional view of a

  turbine showing the end of a winglet and the part

  sinante of the casing which surrounds it; fig. 2 is a sectional view along II-II of the turbine blade of FIG. 1; fig. Fig. 3 is a turbine efficiency difference diagram as a function of the ratio t (see Fig. 1 and 2); fig. 4 is a difference diagram of yield of

  the turbine as a function of the angle> 6 of inclination of the ra-

  in relation to the radial plane x (see Fig. 1).

  We see in fig. 1 the end of a fin 1 of tur-

  and the neighboring portion 2 of the turbine casing, the flow direction of the fluid through the turbine being indicated by the arrow 3. Each fin here comprises as seen in FIG. 2 a concave high pressure side 4 and a convex low-pressure side 5. The housing 2 has internally, in the vicinity of the end of the fins, several parallel grooves 6 of width b separated by thin walls 7 thick

  a, these grooves preferably having a rounded bottom 8.

  It has been found that the depth of the grooves should not be too great as this may affect their efficiency and the efficiency of the turbine, and that there must be a relationship between their depth d and the thickness of the ends of the fins. indicated in t in fig. 2. The efficiency is improved when the ratio d is less than 1 or even when inversely the ratio d is greater than 1, as shown in the diagram of d t in FIG. 3. This diagram has on the x-axis the ratio - and

  on the y-axis the difference in yield, s R. In the case of em-

  The use of finned fins, small heads or small bandages may be provided at their ends to increase the width of the tip. The following results with a finned turbine having an axial depth of 13.7 mm and an angle of about 45 with respect to the rotor axis result from tests in which the efficiency was measured in relation to that of a turbine having a crankcase

  grooved and otherwise identical features.

  tdbtd R 4R d Ex.I 4,34mm 3,81mm 1,27mm 3,42 1,14 90,9 + O, 1 Ex.II 1, 85mm 3,81mm 1,27mm 1,46 0,49 90,2 -0.4 Ex.III 1.85mm 1.52mm 1.27mm 1.46 1, 22 90.7 + O, 1 Within the framework of these provisions, it has also been found that it is preferable to provide at least four grooves 6 on the axial depth of the end of the fin, these grooves having

  a depth preferably between 1.27 mm and 3.81 mm.

  In addition, as shown in FIG. 1, the grooves 6 are inclined at an angle e with respect to the radial plane x perpendicular to the axis of the turbine, and it has been found that a better yield is obtained by tilting them towards the flow inlet of the fluid in an angle between 10 and 400,

2 498679

  and preferably between 20 and 300 as giving the best result from the diagram of FIG. 4, in which

  has represented on the abscissa the angle g and on the ordinate the difference

  Compared with a turbine having a non-grooved housing and otherwise identical characteristics, the efficiency of R is measured.

  Of course, many variants can be imagined

  born while remaining within the scope of the invention.

Claims (4)

  A turbine housing surrounding a multi-fin rotor having ends adjacent to the housing, said   housing comprising a plurality of circumferentially extending grooves   at the end of the fins, according to claim 1 of the main patent, characterized in that said grooves (6)   are such that the ratio between their depth (d) and the thickness   (t) of the thickest part of the wingtips is less than unity.   2. Turbine casing surrounding a multi-vaned rotor whose ends are adjacent to the housing, said   housing comprising a plurality of circumferentially extending grooves   at the end of the fins according to claim 1 of the main patent or claim 1 above, characterized in that said grooves are inclined (6) with respect to the radial plane (x) perpendicular to the axis of the turbine and towards the fluid flow inlet of an angle of between 10 and 400, preferably between 20 and 300   3. A turbine casing according to any one of the   previous cations, characterized in that it comprises at least four of said grooves in the axial depth of the blade tip.   4. Turbine casing according to any one of the   prior art, characterized in that said grooves   have a depth of between 1.27 mm and 3.81 mm.