SU1562474A1 - Francis turbine - Google Patents

Abstract

The invention can be used in the design of turbines of various purposes with high energy indices and allows to increase the efficiency of the turbine by eliminating separated currents in the impeller. The radii R and R _{n ext} inner and outer contours 5 and 6 are determined by the formula according to: Z - coordinate along the wheel axis 3

R ₁ - outer radius of the wheel 3

L ₁ , L ₂ - the height of the blades 4 of the impeller 3 at the entrance and exit, respectively

R ₂ - the average radius of the wheel 3 at the exit

B - wheel width 3. The U coordinate of the middle line of the blade profile 4 is chosen according to the formula depending on: R - the current radius of the impeller 3

Z _p - the number of blades 4 of the impeller 3

β ^{cf is the} corner of the blade 4 at the exit of the impeller 3 at radius R ₂ . The thickness D _Z profile of the blade 4 is chosen according to the formula depending on: D ₂ , D _2K , D _2B — thickness of the output edge of the profile of the blade 4 when it is cut with cylindrical surfaces of radius R = CONST, R ₁ = CONST and (R ₂ - L ₂ / 2) = CONST respectively

Z - coordinates along the axis of the wheel 3

B is the width of the wheel 3 and the coefficient K _Z = 10.4 - 0.8. Profiling the flow part of the impeller 3 according to these formulas makes it possible to eliminate the separation currents in the wheel 3, which allows to obtain a higher efficiency. In addition, such profiling provides a radial arrangement of the forming blades 4, which predetermines the absence of bending stresses in them from centrifugal forces during rotation of the wheel and ensures the strength and reliability of the design. 4 il.

Description

va blades 4 impeller 3; the angle of the blade 4 at the exit of the impeller 3 at a radius R. The thickness dz of the profile of the blade 4 is chosen according to the formula depending on: d2, dZK, da & - thickness of the output edge of the profile of the blade 4 at its cross section by the cylindrical surfaces of radius R const, R, const and (Ru - lu / 2) const, respectively; Z - coordinates along the axis of the wheel 3; B - wheel width 3 and coefficient Kz 10.4 - 0.8. Profiling the flow part of the impeller 3 according to these formulas makes it possible to eliminate the separation currents in the wheel 3, which allows to obtain a higher efficiency. In addition, such profiling provides a radial arrangement of the forming blades 4, which predetermines the absence of bending stresses in them from centrifugal forces during rotation of the wheel and ensures the strength and reliability of the design. 4 il.

The invention relates to turbine engineering and can be used in the design of turbines for various purposes with high energy indices.

The purpose of the invention is to increase the efficiency of the turbine by eliminating. no tearing currents in the impeller. FIG. 1 shows a turbine, longitudinal section; in fig. 2 is the middle line of the profile in angular coordinates on a cylindrical surface R const with the Z axis; in fig. 3 — average line of a profile in linear coordinates on cylindrical surfaces R, const, Rj, const, R4 - 12/2 const; in fig. 4 - solid profile of a blade on a cylindrical surface R const.

The radial-axial turbine contains an inlet 1, a radial blade 40 precision nozzle apparatus 2 and a radial

 but-axial closed impeller 3. with blades 4 and external and internal

contours 5 and 6. Radii R6H and RH of the inner and outer contours 6 and 45 5 in the meridional plane are selected i in accordance with the equations

RBH. U-R ™ 4 -) - Kts Rf.Ml.Rt. Jl)

Rj,

L;

Ri

It.

KI

Z B5

7 Z

i,

Z - coordinate along the axis of the wheel 3; outer radius of the wheel 3; 1, DD - the height of the blades 4 of the impeller 3 at the entrance and exit, respectively;

 average radius of the wheel 3 at the exit;

B is the width of the wheel 3. The coordinate of the centerline of the profile of the blade 4 is chosen in accordance with the equations

U-R-H at 0 Ј Z B-b, at B - 1, Z i B, Cf A- (l - Z) 6,

,

where A Cft + u, B A D - (0.7 - 0.8)

j - the angular coordinate of the average

profile lines;

R is the current radius of the impeller 3; Zp - the number of blades 4 working

R

Wed Ch

wheels 3, - the angle of the blade 4 at the exit from

impeller 3 ce R,

on the radium

thickness dz blade 4 profile knocking out according to the equation

55

,,. „,, - ЈЈ.

- - | m i,

12V

R

5 1

EiJL djic R

Y,

Kz (0.4-0.8);

d, d2K, dl & are the thickness of the output edge of the blade 4 profile when it is cut with cylindrical surfaces of radius R const, R const and (Ra-l2 / 2) const, respectively.

During turbine operation, the working fluid enters the inlet nozzle 1, made in the form of a cochlea, uniformly distributing it through the nozzles of the nozzle unit 2. The passage through the impeller 3 with blades 4, the working fluid gives it energy. Profiling the flow part of the impeller 3 of a radial-axial turbine according to the above formulas allows to create a series of turbines, in the flow part of which there are no separated currents, which allows to obtain a high efficiency. Such profiling both bakes the radial arrangement of the forming blades 4, which predetermines the absence in them of bending stress and centrifugal forces during rotation of the wheel 3 and, therefore, ensures the strength and reliability of the design. Such a blade shape 4. allows you to get the wheel 3 by milling a cylindrical mill on a numerical control milling machine. This does not require a set of shaped cutters, the impeller 3 treatment program is greatly simplified, the labor / production complexity of the impeller is reduced.

Claims (1)

Invention Formula A radial-axial turbine containing an inlet, a radial blade nozzle and a radial-axially closed impeller with blades and external and internal contours, so that, in order to improve efficiency by eliminating tear-off currents in the turbine impeller, the radii inner ReH and outer R, H contours in the meridional plane are selected in accordance with equations  ) 2 R2 + R, l- (1- RH R, l- (1-R - Jkj.-Ji-z; 7 - 2. L b-l Z - coordinate along the wheel axis; R, is the outer radius of the wheel; 1, 12 - the height of the impeller blades, respectively, at the entrance and exit; R is the average radius of the wheel at the exit; B is the width of the wheel, the U coordinate of the middle line of the blade profile is chosen in accordance with the equation U R with at 0 Z B - 1 ,, U 0 at B - 1, Z B, If A (1-Z) 6 where A (f i + L; AT - ctgPS. d 2 HH z5 ZP U (0.7 - 0.8) ftj. LP - the angular coordinate of the average profile line, happy; R is the current radius of the impeller; Zp - the number of blades of the impeller; L ° R m- - the angle of the blade at the exit of the impeller at a radius R {, and the thickness dz of the blade profile is selected in accordance with the equation dz GKz Z 1 1 + -ag 50 where d, (R, - b) + L; l- (Rt-lt / 2) L2 J Cvr Eli dfl R R, Kz 0.4 - 0.8; d d2 ((, d / 26 - thickness of the output edge of the blade profile at its cross section by cylindrical surfaces of radius R const, P Compiled by A. Zitynyuk Editor N. Yatsola Tehred.Didyk Order 1043 Circulation 429 VNIIPI State Committee for Inventions and Discoveries at the State Committee on Science and Technology of the USSR 113035, Moscow, Zh-35, 4/5 Raushsk nab. R 4 const and (Kr - 12/2) const, respectively. Figm Corrector S.Cherni Subscription