RU2104413C1 - Liquid-packed ring-type machine - Google Patents

Abstract

FIELD: manufacture of compressors and vacuum engineering. SUBSTANCE: blades of liquid-packed ring-type machine are bent in peripheral portion in opposite direction relative to sense of rotation forming angle between tangent lines to circle of wheel and line of bending of blade at point of their connection lying between 90 and 160 deg. EFFECT: enhanced efficiency. 2 cl, 4 dwg, 1 tbl

Description

 The invention relates to compressor engineering and vacuum technology, in particular, to liquid ring pumps and compressors.

 Known liquid ring machine (LCM), comprising a housing, end caps with channels for supplying and discharging a working medium, an eccentrically placed impeller with blades curved in the direction of rotation (A. Golovintsov, Rotary compressors.- M .: Mashgiz, 1964. p. 153, Fig. 97).

 The disadvantage of this design is the low efficiency due to power losses to overcome the friction forces in the bladeless region and the high material consumption of the structure.

 The closest in technical essence is the LCM, comprising a housing, end caps with suction and heating windows, a rotor with radial blades eccentrically placed in the housing, the opposing blades being connected to each other through diametrical channels. A longitudinal groove is made in each blade from the outside, communicating with the diametric channels, while the latter in the adjacent blades are displaced axially relative to each other (USSR AS N 1548520, class F 04 C 7/00, 1990).

 The disadvantage of this design is the low efficiency due to power losses due to vortex formation in the bezoplatochny space.

 The technical task is to increase the efficiency and weight and size characteristics of the LCD.

The task in a liquid ring machine containing a housing, end caps with suction and discharge windows, an eccentrically placed impeller with blades made radial at its base, is achieved by making the LCD wheel curved against the direction of rotation in the peripheral part to form an angle between the tangents to the wheel circumference and the line of bending of the blades at the point of their connection is in the range of 90-160 ^o .

In addition, the curvature of the blades can be performed along an arc of a circle with a minimum radius R _and , determined from the ratio of R _and > 0.15 R _k , where R _k is the radius of the wheel.

It is known (Frolov E.S. et al. Mechanical vacuum pumps.- M .: Mashinostroenie, 1989) that the amount of power N consumed in the LC is proportional to the absolute velocity of the liquid C ₂ cast by the wheel blades into the bladeless space in the third degree, i.e. e. N ≈ C $\genfrac{}{}{0ex}{}{\text{3}}{\text{2}}$ . Then, to reduce power consumption, it is necessary to reduce the value of C ₂ .

It is also known that a decrease in C _{2 is} achieved by increasing the exit angle of the blade β _2l to a value of more than 90 ^o due to the bending of the blade against the direction of rotation, i.e. back (Stepanov A.I., Centrifugal and axial pumps.- M.: Mechanical Engineering, 1960).

With constant values of N and C ₂ for a particular machine, an increase in β _{2l of} more than 90 ^o with a simultaneous increase in the rotor speed n will lead to an increase in the overall dimensions of the LCD.

 Figure 1 presents a liquid ring machine, which contains a housing 1, end caps 2 with suction and discharge windows 3 and 4, an eccentrically placed impeller 5 with blades 6, radial at its base and curved against the direction of rotation in the peripheral part.

- переносные составляющие абсолютных скоростей; W₂,

- относительные составляющие абсолютных скоростей.In FIG. 2 presents fragments of the LCD wheel: a - the wheel blades are bent forward, b - the blades are bent back, c - the radial blades, where U ₂ ,

- figurative components of absolute speeds; W ₂

- relative components of absolute speeds.

Figure 3 presents a fragment of the LCD wheel with blades made radial at its base and curved against the direction of rotation in the peripheral part along an arc of a circle with a minimum radius R _and determined from the ratio R _and > 0.15 R _k , where R _k is the radius wheel, and the angle between the tangents to the circumference of the wheel and the bending line of the blade at the point of the connection is in the range of 90-160 ^o .

 Figure 4 presents a fragment of the wheel of the LCD with blades made as in figure 3, indicating the geometric parameters that determine the specified shape of the blade.

R₁ = 0,4 R_к,
где
β_2л - угол между касательными к окружности колеса и линии изгбиа лопатки в точке их соединения;
R_к - радиус колеса;
R₁ - радиус ступицы;
R_С - радиус перехода радиальной части лопатки в изогнутую;
R₃ - радиус центра изгиба;
R_и - радиус изгиба периферийной части лопатки.From the experience of designing LCMs for the Bessonovsky KZ and Sumy NPO, we know the relations for the geometric parameters that determine the shape of the blades radial at their base and bent in the peripheral part along an arc of a circle:

R ₁ = 0.4 R _to
Where
β _2l - the angle between the tangents to the circumference of the wheel and the line of the curved blade at the point of their connection;
R _to - the radius of the wheel;
R ₁ is the radius of the hub;
R _C is the radius of the transition of the radial part of the blade to the curved;
R ₃ is the radius of the center of bending;
R _and - the bending radius of the peripheral part of the scapula.

.Define the ratio of the radius of bending of the blade R _And the radius of the wheel R _to :

.

We take the angle of exit of the blade β _2l equal to β _2l = 90-160 ^o . The upper limit of the range is limited by the impossibility of bending the scapula over a given value. The lower boundary is limited by the disappearance of the beneficial effect of bending the blades against the direction of rotation. Finally:
R _and / R _k = 0.15 ... ∞, i.e. R _and > 0.15R _k .

The implementation of the blades curved against the direction of rotation radial at its base allows you to best interconnect the movement of fluid in the bladeless space and the gas parameters in the interscapular. Since the gas pressure in the considered interscapular channel (wheel cell) is determined by the fluid velocity in the bladeless space, it is necessary to limit the angle ψ formed by a straight line drawn through the center of the wheel and the base point of the blade on the hub, and a straight line drawn through the center of the wheel and the end point scapula (figure 4). Usually in the LCM ψ is equal to ψ = 10-15 ^o . With an increase in ψ over 15 ^o (as it will be for blades bent back along their entire length, without a radial section), stable operation of the LCM is observed.

Consider, for example, the currently commercially available ZhKM - VVN1-12M with blades radial at its base and curved in the direction of rotation in the peripheral part, equipped with an electric motor with a rotation speed of 1000 rpm, and a ZhKM made on the basis of VVN1- 12M, but with a wheel having blades made radial at its base and curved against the direction of rotation in the peripheral part so that the angle between the tangents to the wheel circumference and the bend line of the blade at the point of connection in the range of 90-160 ^o
The calculation of the efficiency and productivity of the compared machines was carried out according to the methodology for calculating LCM (Frolov ES, et al. Mechanical vacuum pumps.- M .: Mechanical Engineering, 1989) at a suction pressure of 20 kPa.

 The calculation results are shown in the table.

The table shows that the implementation of the LCD blades radial at its base and curved against the direction of rotation in the peripheral part so that the angle between the tangents to the wheel circumference and the bend line of the blade at the point of their connection is within 90-160 ^o , allows to increase the efficiency LCD for 8-14%.

 In addition, with an increase in the rotational speed without a significant decrease in efficiency, the overall dimensions of the LCD are improved due to an increase in productivity by 50%.

 The liquid ring machine operates as follows.

When the wheel 5 is rotated, a liquid ring is formed. On the suction side, the liquid exits between the blades 6 of the wheel 5 to the housing 1 and gas is sucked in through the suction windows 3. On the compression side, the liquid enters between the blades 6 in the wheel 5 and pushes gas into the discharge ring 4. The LCD blades are curved against the direction of rotation in the peripheral parts with the formation of the angle between the tangents to the circumference of the wheel and the line of bending of the blades at the point of their connection within 90-160 ^o leads to an increase in the efficiency of the liquid ring machine, as the power losses on the vortices are reduced ianie.

Claims (2)

1. A liquid-ring machine containing a housing, end caps with suction and discharge windows, an eccentrically placed impeller with blades made radial at its base, characterized in that in the peripheral part of the blade is made curved against the direction of rotation to form an angle between the tangents to the circumference of the wheel and the bending lines of the blades at the point of their connection, which is within 90 180 ^o . 2. The machine according to claim 1, characterized in that the curvature of the blades is made along an arc of a circle with a minimum radius R _and determined from the ratio R _and > 0.15 R _k , where R _{k is the} radius of the wheel.

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