A kind of centrifugal pump with low-noise characteristic
Technical field
The present invention relates to a kind of centrifugal pump, refer in particular to a kind of centrifugal pump with low-noise characteristic, belong to field of fluid machinery.
Background technique
Centrifugal pump is a kind of universal machine, in the every field of national economy, all play important role, and it is efficient, to safely and steadily run be the final goal that Centrifugal Pump Design is pursued; Spiral case is the important composition part of centrifugal pump, its Main Function is the liquid collection by going out stream from impeller, and eliminate the turning effort of fluid, because the discharge section area of spiral case constantly increases, therefore the kinetic transformation of liquid can also be become pressure energy by effectively, thus reduces the loss of flowing; Simultaneously when impeller periodic performance is by spiral case cut water, larger pressure pulsation will be produced, this kind of phenomenon is called the stator-rotor interaction effect of impeller-cut water, this effect is the important sources of centrifugal pump vibration noise, and have strict requirement in some field (petrochemical industry, nuclear power) the vibration noise performance to centrifugal pump, too high vibration noise serious harm, must the content considered of emphasis when therefore low-noise performance is also Centrifugal Pump Design to stable, the safe operation of pump.
In current Centrifugal Pump Design process, general emphasis considers the efficiency of pump, to reach the object of energy efficient, makes centrifugal pump reach the highest working efficiency by the geometrical structure parameter of optimization impeller, spiral case; Low noise ACTIVE CONTROL aspect in Centrifugal Pump Design process, current research also mainly concentrates on the geometric parameter optimizing impeller and comprises the number of blade, blade import and export laying angle, cornerite, vane type line etc., has lower vibration noise level to make centrifugal pump.Another approach is that impeller by proposing some special constructions, spiral case are to reach Low Noise Design object; Such as its a kind of centrifugal pump impeller with deviated splitter vane structure proposed of Jiangsu University Yuan Shou, Yang Minguan proposes a kind of centrifugal pump lateral wall type pressurized water chamber structure and has clear and definite Low Noise Design object; The stator-rotor interaction effect of impeller-cut water is the important sources of centrifugal pump noise, and therefore the shape of cut water, angle will have an impact to centrifugal pump vibration noise, but in Centrifugal Pump Design process, the matching properties of cut water and impeller is then often left in the basket.Therefore the present invention is from the matching properties improving cut water and impeller, by definition cut water angle, and the relation of itself and blade outlet angle, thus reach the object of low noise centrifugal pump design.Design for low noise centrifugal pump is provided new solution route by the present invention.
Summary of the invention
In order to reduce the vibration noise level of centrifugal pump, the present invention is from reduction impeller-cut water stator-rotor interaction effect, by improving spiral case cut water angle and the matching relationship with blade outlet angle thereof, thus obtaining a kind of centrifugal pump with low-noise characteristic, reduce further centrifugal pump vibration noise level.This worm frame is simple, reasonable, has the characteristics such as easily enforcement, effectively can weaken the percussion that impeller goes out flowing liquid and cut water, thus improve the vibration noise level of centrifugal pump further.
The present invention proposes a kind of centrifugal pump with low-noise characteristic, comprise spiral case, it is characterized in that: the arc-shaped edges mid point of spiral case cut water and the line in the circular arc center of circle of spiral case cut water and the angle of Vertical direction are defined as cut water angle φ, the noiseproof feature of matching relationship on centrifugal pump of this angle and blade outlet angle β has fairly obvious impact, as φ=[(β-5 °) ~ (β+5 °)], centrifugal pump can obtain good low-noise performance, and centrifugal pump is now called low noise centrifugal pump.
This spiral case and impeller are installed with one heart, spiral case inlet limit diameter D
2be greater than impeller outlet diameter D
1, both ratio spans are D
2/ D
1=1.05 ~ 1.2; The line of cut water arc-shaped edges mid point and impeller central point and the angle theta of substantially horizontal are defined as cut water laying angle, and its span is 15 ° ~ 45 °; Blade outlet angle
, the absolute flow angle of impeller outlet
, the circumferential components of impeller outlet absolute velocity
, impeller outlet axis plane velocity
, impeller outlet peripheral velocity
, n is the rotating speed of pump, and b is impeller outlet width, and therefore blade outlet angle comprises flow, rotating speed and cut water laying angle by the geometrical structure parameter of centrifugal pump impeller and performance parameter and jointly determines.
Advantage of the present invention is: from the effect of impact reducing impeller outlet fluid and cut water, by improving the matching relationship at cut water angle and blade outlet angle, fluid is made smoothly to be passed through cut water, and then weaken the percussion of fluid and cut water, reach the object reducing centrifugal pump noise, the centrifugal pump of this kind of structure spiral case is low noise centrifugal pump.The present invention simultaneously also has the advantages such as simple and reasonable for structure, easy to process.
Accompanying drawing explanation
Below in conjunction with accompanying drawing, the invention will be further described.
Fig. 1 is the centrifugal pump axis projection with low-noise characteristic of the present invention.
Fig. 2 is the centrifugal pump plane figure with low-noise characteristic of the present invention.
In figure, 1 is impeller, and 2 is blade, and 3 is impeller outlet limit, and 4 is spiral case, and 5 is spiral case inlet limit, and 6 is cut water arc-shaped edges, and 7 is the mid point of cut water arc-shaped edges, and 8 is the circular arc center of circle, and 9 is impeller central point.
Embodiment
Fig. 1 gives the centrifugal pump axis projection with low-noise characteristic of the present invention, as shown in Figure 1: spiral case inlet limit 5 diameter is greater than impeller outlet limit 3 diameter, and D
2/ D
1=1.12; The centrifugal pump plane figure with low-noise characteristic is given, as seen from the figure: the angle of the mid point 7 of cut water arc-shaped edges and impeller central point 9 line and substantially horizontal is taken as 20 ° by Fig. 2.
The computational methods of blade outlet angle are described below in conjunction with performance of centrifugal pump and geometric parameter, and in this example, Centrifugal Pump is Q=55m
3/ h, rotating speed n=1450r/min, impeller outlet diameter D
1=260mm, impeller outlet width is b=16mm, blade exit laying angle β
2=30 °, cut water laying angle θ=20 °.
Computational process is as follows:
Impeller outlet peripheral velocity is:
.
Impeller outlet axis plane velocity is:
.
The circumferential components of impeller outlet absolute velocity is:
.
The absolute flow angle of impeller outlet is:
.
Blade outlet angle:
.
Therefore: φ=β ± 5 °=11.2 ° ~ 21.2 °.
That is:, when cut water angle is 11.2 ° ~ 21.2 °, the matching properties of spiral case and impeller is best, and the vibration noise level of centrifugal pump is lower, and now spiral case has low-noise characteristic.
Theory analysis is thought: the effect of impact of the fluid that centrifugal pump impeller flows out and spiral case cut water is the important sources of pump vibration noise, therefore weakens the vibration noise level that this effect of impact can reduce centrifugal pump effectively; The present invention goes out to flow the angle of fluid impact cut water from optimization impeller, by improving the matching properties of impeller-spiral case, and then reaches the object of Low Noise Design.
By finding after numerical calculation (CFD) checking: compare with the centrifugal pump of conventional design, adopt the centrifugal pump of this kind of method design effectively can reduce the pressure pulsation level of centrifugal pump inside, amplitude of pressure fluctuation reduces 5-10%, and then reducing the vibration noise energy of centrifugal pump, the centrifugal pump of this kind of structure of therefore the present invention's proposition has low-noise characteristic.