A kind of have a radially low specific speed centrifugal impeller of return port
Affiliated technical field
The present invention is a kind of radially low specific speed centrifugal impeller of return port that has, the Impeller Design specific speed is less than 80, and the number of blade is greater than or equal to 3, seal ring before and after impeller has, and supporting dry type threephase asynchronous belongs to universal machine product manufacturing technology field.
Low specific speed centrifugal pump has the advantages that flow is little, lift is high, is widely used in the industries such as agricultural drainage and irrigation, mine, petrochemical industry.Have the characteristics that the blade exit width is less, impeller outer diameter is large, flow channel of axial plane is narrow and grow on the low specific speed centrifugal impeller geometrical shape.The low specific speed centrifugal impeller has forward and backward seal ring usually, the diameter of front and back seal ring is generally identical, offer axial return port between increasing back sealing ring and the wheel hub, the highly pressurised liquid that the impeller increasing back sealing ring leaks is back to the entry zone of impeller usually by axial return port, reduced the axial force that acts on the back shroud of impeller, so that the axial force that acts on the impeller is in a basic balance, usually the gross area of getting axial return port equals five times increasing back sealing ring interval area, and the leakage rate of return port is generally the 2%-5% of Impeller Design flow at this moment; Also there is the mode in special-purpose connecting tube of pump outer installment to reflux.Because of low specific speed centrifugal impeller lift height, the leakage rate of impeller increasing back sealing ring gap location is larger, original axial return port backflow direction comes flow path direction consistent with impeller, destroyed normal flowing state, impeller inlet place current are disorderly, the decrease in efficiency that causes pump, pump easily forms abnormal vibrations and noise, and the anti-cavitation performance of pump descends, when pump operation less than the design discharge operating point time, lift of pump is higher, and increasing back sealing ring place leakage rate is larger, and the liquid that return port refluxes is larger to the interference of impeller inlet incoming flow.If adopt the mode of special-purpose connecting tube of outer installment to reflux, pump structure is complicated on the one hand, and the high pressure liquid stream energy that refluxes on the other hand can not reclaim.
Summary of the invention
In order to improve existing low specific speed centrifugal impeller efficient and anti-cavitation performance, the invention provides and have the radially low specific speed centrifugal impeller of return port, be applicable to design specific speed less than 80 loaw specific speed pump, the number of blade is greater than or equal to 3, can be used for single-stage pump or multistage pump, supporting dry type or submersible three phase asynchronous motor, so that the leakage rate of low specific speed centrifugal impeller increasing back sealing ring is back to the direction basically identical with blade influent stream direction, reclaim the energy of highly pressurised liquid, improve the fluid pressure of blade inlet, so that the efficient of low specific speed centrifugal pump and anti-cavitation performance improve.
The technical solution adopted for the present invention to solve the technical problems is:
Change the axial reflux type of rate revolution centrifugal pump impeller, at the impeller hub processing axial return port identical with the number of blade, and radially process return port at impeller lock jack panel fitting surface, impeller nut is with after impeller cooperates, original axial reflux type will change over radially and to reflux, and this radially refluxes substantially identical with impeller blade inlet flow direction.This will effectively improve the impeller internal flow, improve the low specific speed pump efficiency, improve the cavitation performance of loaw specific speed pump.
As long as increase slightly hub diameter, do not affect wheel hub at several axial return ports of impeller hub processing and transmit the needed moment of torsion of vane rotary, and as long as directly boring; Also only need utilize the milling cutter cutting to get final product and radially process return port at impeller lock jack panel fitting surface, even can directly cast out radially return port.Therefore, the present invention increases cost of production hardly, and is very easy to realize.The invention has the beneficial effects as follows, improved the efficient of loaw specific speed pump with minimum cost of production, improved the cavitation performance of loaw specific speed pump, thereby provide the more low specific speed centrifugal pump of reliable and energy-saving to the user.
Description of drawings
The present invention is further described below in conjunction with drawings and Examples.
Accompanying drawing 1 is the main sectional view that does not adopt loaw specific speed pump example commonly used of the present invention; 1. pump housings among the figure, 2. impeller, 3. impeller nut, 4. return port, 5. impeller increasing back sealing ring, 6. impeller hub, 7. mechanical seal, 8. axle, 9. bearing support, 10. bearing.
Low-specific speed impeller goes out oral fluid stream and has high pressure and high-energy with respect to the impeller inlet district, a part of q of liquid stream will be through circumferential play, the return port 4 of impeller increasing back sealing ring 5, again get back to the impeller inlet district, and the backflow direction of q is opposite with main flow direction, to form larger interference to main flow, so that pump efficiency reduces, cavitation performance descends.
Accompanying drawing 2 is not adopt low-specific speed impeller commonly used of the present invention, and its return port is between increasing back sealing ring and wheel hub, and its backflow direction is opposite with main flow direction.
Accompanying drawing 3 is the main sectional views that adopt one embodiment of the invention; 1. pump housings among the figure, 2. impeller, 3. impeller nut, 4. return port, 5. impeller increasing back sealing ring, 6. impeller hub, 7. mechanical seal, 8. axle, 9. bearing support, 10. bearing.The reflux type of impeller 2 is changed into radially.
Accompanying drawing 4 is for to adopt the radially low specific speed centrifugal impeller of return port, vertically boring on impeller hub, hole count is identical with the impeller blade number, and this axial bore between the neutral position of blade (such as Fig. 4 right elevation, α
2); On impeller lock jack panel fitting surface, take the axial bore position as starting point, mill out or cast out radially return port, radially return port quantity is identical with the number of blade, radially return port is towards the opposite direction of the vane rotary a certain angle beta of setovering, so that this radially the center line of return port be connected the angle that wheel hub through hole central point forms between the straight line with the impeller central point be the complementary angle of 0.5 times of spacing with blades angle, the impeller central point connects wheel hub through hole straight line that central point forms and is comprising this radially on the horizontal section of the impeller of the center line of return port, radially return port quantity is identical with the impeller blade number for this, and this radially return port and impeller hub axially the through hole of processing be communicated with.
Radially the low specific speed centrifugal impeller of return port is mounted to running shaft, after impeller nut is tightened, the liquid stream that leaks from the impeller increasing back sealing ring will radially be back in the runner between two blades, compare with common low specific speed centrifugal impeller, and backflow direction and main flow direction are without obvious bump.The present invention has only changed the direction of operative position and the return port of return port, increases hardly cost of production.