SU759732A1 - Centrifugal partial turbine - Google Patents

Description

The invention relates to the field of turbine construction and can be used with reference to small-sized turbines.

The closest solution of the known is a centrifugal partial turbine containing a fixed nozzle apparatus and a blade impeller [1]

However, this turbine is not reliable enough.

The aim of the present invention is to improve the efficiency and reliability.

This goal is achieved by the fact that the ratio of the total flow areas at the exit of the nozzle apparatus P, and the impeller G ₂ is:

P = 1-2.8

g g

the ratio of the pitch ί of the interscapular channels to the width of the impeller is £ = 1.2-1.5, and the ratio of the chord in ι and _2, respectively, of the concave and convex surfaces of the interscapular channels is

"Ι о

where a is the average width of the working channel.

2

FIG. 1 shows a turbine, a longitudinal section; in fig. 2 - nozzle placement scheme; in fig. 3 - the form of working channels.

The centrifugal partial turbine contains a pipe 1 for supplying a working fluid, _{5 a} fixed nozzle apparatus 2 with nozzles 3 occupying only a part of a circle (partial inlet). The stationary nozzle unit 2 is enclosed by a detachable blade impeller 4, whose walls near the periphery together with the peripheral wall of the nozzle unit 2 form the distributor 5 in the form of a tapering channel, at the outlet of which are working channels 6, made in the peripheral wall of the impeller 4. Step such working channels 6 depends on the flow of the working fluid, its ¹⁵ parameters, speed and requirements for the strength of the impeller. It differs by a large amount from the pitch of the working channels in ordinary partial turbines. For impellers having a practical value of 20, the relative pitch is within

1 = 1.2- 1 5,

where ί - and B - the width of the impeller.

-Ta ^ y.-dl

759732

In some cases, this step is an order of magnitude more than the relative step of the working blades in conventional partial turbines.

Another geometrical parameter that characterizes this class of impellers - _ί ratio of flow areas at the outlet of the nozzle 2 (1)) and the outlet of the impeller 4 (P _2):

P = ^ - = 1-2.8 th

'’G

This ratio covers the class of partial impellers of practical importance. When predetermined physical properties of the working fluid, the degree of pressure reduction in the nozzles and working channels and the pack ¹⁵ odi- largest energy loss value R is kept constant regardless of check working fluid flow, whereas in a conventional partial-stage inlet degree value under the same conditions may vary with with a change in consumption by tens of times. ''

The working channels 6 are bounded by strongly curved surfaces in the central part, where the flow is mainly rotated, and by weakly curved surfaces ²⁵ at the inlet and outlet sections. The rotation of the flow in the working channels can vary from 90 ° for the reactive stage to a value close to 180 ° for the active type stage. _thirty

For the efficiency of the impeller 4, the most important are the surfaces that form the central part of the working channel 6. Their main characteristic can be expressed through the chord ratio in, =

= CE) arc convex surface to the chord l B2 -AE arc of the concave surface of the channel. Depending on the properties of the working fluid of the point A and C on the one hand, and ^! points C and E on the other hand can be placed respectively on the same radii (r1 = Gg, Ge =

= r <and c = _c ), or at different radii (y> r ^ r> rz) 'with displacements of 11 and 12, with this, different angles and outlines of edges are obtained when entering the working channel and leaving it. The greatest angle is 45 gate at the location of points

A, B, C, and B in one meridional section. The main parameter of the working channel - the chord ratio is calculated by the formula

(a, ♦ a? / ® ^{2 = b2 (a / b)} '

where a = - ^ —'— the average height of the channel;

B = g ₊ -g, is the width of the crown of the worker to ¹ forest.

Of practical interest are the edge shifts within the limits defined by the formula:

(- £ * -) (= I-0.8 (1-2 (a / B)).

61

At the same time, working channels 6, depending on the degree of reactivity and relative flow rate, can be performed with equal live sections (a = const!) As tapering (a,> a ₂ ) or expanding (a | <o 2) ·

Centrifugal partial turbine of this design will increase its efficiency and reliability.

Claims (1)

Claim A centrifugal partial turbine containing a stationary saver device and a blade impeller, characterized in that, in order to increase efficiency and reliability, the ratio of the total flow areas at the exit of the nozzle apparatus P, and the “impeller P ₂ is:. '' 4 Р = -р— = 1-2,8 the ratio of step ί interscapular channels to the width of the impeller is = 1.2–15, and the ratio of the chord in and in g, respectively, the concave and convex surfaces of the interscapular canals is £ = 1-0.8 (1-2 ^) where a is the average width of the working channel.