The function of the flow guide is carried out by the flow guide, as shown in the structural diagram of the flow guide
The performance range of this pump is flow rate%& The head of 054 is 54%
The J-type multi-stage pump is composed of multiple single suction impellers! The form of liquid flow in the pump body is shown in Figure # 3D, and it can be seen from the figure that
See! The axial thrust of the J-type multi-stage pump will increase with the increase of the number of impellers! Therefore! The balance of axial force is a
Figure # 3% guide vane centrifugal pump
* Flow groove $# * Fixed bolt hole $$* Water pump impeller $0 * Pump casing
The issue that cannot be ignored is to eliminate axial thrust!
Usually at the last stage of the water pump! Install the balance plate device!
As shown in Figure # 3? The balance plate device is mainly achieved through balancing
Reduce axial unevenness by relative changes in indoor water inflow and outflow
The balance plate is fixed to the shaft with a key pin! Follow the shaft
Rotating together, it can be regarded as the same as the pump shaft and impeller
A rigid body! And the pump casing and pump seat are considered as another
When the pressure water at the outlet of the last stage impeller is rigid
When a portion flows through the axial clearance A to the balance chamber! balance
There will be one indoors! The force of 9T acts on the inside of the balance plate
On the surface! Its value is! 9T1 $<&5% 5 is balanced
The area of the disk&! Its direction is related to the axial force of the water pump! nine
On the contrary, for example, when 9T approaches 9, for the pump shaft, it means the force that moves it to the left and the axial force that moves it to the right
Balance! So we call it! 9T is the balance force of axial force during the operation of the water pump! Due to the variable outlet pressure of the water pump!
Therefore! Axial force! 9T is also changing! When! 9%! At 9T! The pump shaft and balance plate move to the right! Disc gap B becomes smaller! discharge
The leakage also decreases! But because the axial clearance A remains constant! At this moment! Balancing indoor water intake with less outflow! Balance chamber pressure
$<&5 value increases! That is, the balance force to the left! 9T will increase! Quickly it grows to! 9T1! When the value is 9! Axis and balance
The disk was pulled back to its original balance position from the right side“
After installing a balance plate in the segmented multi-stage pump! The adjustment of axial force imbalance is always possible! The balance plate is always in one position
In dynamic balance! Therefore! The entire rotating part of the pump always undergoes slight axial pulsation on the left and right sides of a certain equilibrium position“
Generally, water pump factories display the final assembly drawing of the water pump! For the water pump after installing the balance plate! The axial displacement has clear technical requirements“
’,
As shown in Figure # 3%%& As shown! It is a circular ring cast with guide vanes! Fix it on the pump casing with a nut during installation, ensuring that the water flows through the guide
When using it! Like water flowing through the guide vanes of a stationary turbine! Therefore! This multi-stage pump with a guide vane is commonly referred to as
Guide vane centrifugal pump, also known as turbine centrifugal pump&"Figure # 3%% K&shows the movement of water flow in the pump casing"
J-type multi-stage pump is used to transport non solid particles # at temperatures below? 49. Clear water or similar physical and chemical properties to clear water
The liquid! Suitable for mining # factories and urban water supply and drainage“
Chapter 2 Construction, Performance, and Application of Common Water Pumps
Figure # 3D Schematic diagram of liquid flow in J-type multi-stage pump # 3? Balance disk
* Balance chamber $# * Balance disc $* Ventilation port $0 * Impeller pump $5 * Key $% * Pump casing
Also! Attention should be paid! Install the balance plate water pump! Do not use thrust bearings! Because the thrust bearing restricts pump rotation
Partial axial movement! The biggest advantage of losing the automatic balance axial force on the balance plate“
Besides! Arrange each single suction impeller face to face or back to back as shown in the diagram! 3! 4 as shown in&! It can also eliminate
Except for the axial force of the multi-stage pump! But this approach makes the pump structure more complex“
Section 4 Axial and Mixed Flow Pumps
One! Axial flow pump
! The working principle and basic structure of an axial flow pump
The operation of an axial flow pump is based on the lift theory in aerodynamics. When the impeller rotates at high speed, the liquid in the pump body
The physical point will be affected by the axial lift from the impeller! Make the water flow in the axial direction“
The appearance of the axial flow pump is very similar to a water pipe! The diameter of the pump casing is similar to the diameter of the suction port. The axial flow pump can be adjusted according to the working position of the pump shaft
There are three types of structural forms: vertical shaft, horizontal shaft, and oblique shaft. Due to the small footprint of the vertical shaft pump, the bearing wear is uniform, and the impeller is submerged
In the water! Start without watering! It is also possible to use a split support method and place the motor in a higher position! in case
Being submerged by water! Therefore, most axial flow pumps adopt a vertical structure. Figure # 3I%.&shows a vertical semi adjustable section&type axial flow pump
The exterior design! Picture! 3 # 4% K&is shown in the structural diagram of the pump! Its basic components are made up of suction pipes!! Impeller% includes blade #!
Hub body $&! Guide vane 0! Pump shaft?! Water outlet bend D! Upper and lower bearings 5 # I! Filler box# And the adjustment machine for blade angle
Structural composition“
! Suction pipe
The function of the suction pipe is to improve the hydraulic conditions at the inlet! To make the incoming flow stable and evenly flow to the impeller inlet, it is generally used
A streamlined horn tube or made into a channel form“
#Impeller
The possibility of adjusting the impeller of the axial flow pump according to it! It can be divided into fixed # semi adjustable and fully adjustable types. Fixed axial flow pumps
The blades and wheel hub are integrated! The installation angle of the blades cannot be adjusted. The blades of a semi adjustable axial flow pump are bolted with nuts
Tight on the hub body! There is a reference line engraved on the root of the blade! And there are several corresponding installation angle positions engraved on the wheel hub body
Line! As shown in Figure # 3! During use, V0Y # V # Y # 4Y # O # Y # O0Y and other components in 4 can be adjusted based on flow rate and head
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Design and calculation of water pumps and pumping stations
Figure # 3I Vertical Half Side Axial Flow Pump
* Suction pipe $# * blade $* hub body $0 * guide vane $5 * lower guide bearing $% * guide vane tube$
D * Water outlet pipe $* Pump shaft I * upper guide bearing! 4 * Water intake pipe $* Filler$
#* Filler box $$* Cap $! 0 * Pump coupling $! 5 * Motor coupling
Change required! Adjust the installation angle of the blades! Ensure that the water pump operates in the high-efficiency zone, but adjust the blade installation angle! Only when stopped
Figure # 3! 4 Half adjustable blades
* Blade $# * Hub body $$* Adjusting nut
Under the condition of the machine, the fully adjustable axial flow pump can be completed according to different heads and flows
Quantity requirement! With or without shutdown! Through a set of oil pressure regulating machines
Construct to change the installation angle of the blades! So as to change its performance! To satisfy
Use requirements! The regulating mechanism of this fully adjustable axial flow pump is quite complex! General applications
Large scale axial flow pump station“
Guide vanes
In the axial flow pump! When liquid flows through the impeller! Except for axial movement!
There is also a rotational motion with the impeller! Continue rotating after the liquid flows out of the impeller! and
This kind of rotational motion is not necessary for us. The function of the guide vanes is to move the impeller
The upward flowing water flow rotates and changes to axial motion! Transforming the kinetic energy of rotation
For pressure energy! As a result, the efficiency of the pump is improved. The guide vanes are fixed on the pump casing and do not move! When the water flows through the guide vanes, the rotation is eliminated
Rotating motion:% in general axial flow pumps# Blade guide vane“
0 "shaft and bearings
The pump shaft is used to transmit torque in large axial flow pumps! In order to arrange the adjustment # operating mechanism inside the hub! The pump shaft
Often made into hollow shafts! "There are two types of bearings in axial flow pumps according to their functions"
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Chapter 2 Construction, Performance, and Application of Common Water Pumps
%& Guide bearings are mainly used to withstand radial forces! Plays a radial positioning role“
%#&The main function of thrust bearings is in vertical axial flow pumps! Used to withstand the downward direction of water flow on the blades
Axial thrust! The weight of the rotating parts of the water pump and maintaining the axial position of the rotor! And transmit these thrust to the foundation of the unit“
5 "Sealing device
A sealing device needs to be installed at the shaft hole of the outlet bend of the axial flow pump! Currently! Generally, gland packing type seals are still commonly used
Device“
%Water outlet bend pipe
The water outlet bend serves as an overcurrent component of the axial flow pump, playing a role in changing the flow direction! The bending angle is generally% 4Y
Or D5Y“
! Performance characteristics of two axial flow pumps
Compared to centrifugal pumps, axial pumps! Has the following performance characteristics“
%& The head increases dramatically with the decrease of flow rate!! The curve drops sharply! And there is a turning point! As shown in Figure # 3!! As shown in the "
Figure # 3!! Characteristic curve of axial flow pump
The main reason is! Low traffic! At the inlet of the impeller blades and
Backflow generated at the outlet! The water flow is repeated multiple times to obtain energy! similar
In a multi-stage pressurized state! So the head increases sharply, and the reflux causes
Increased loss of water flow resistance! This leads to an increase in shaft power!
The general idle head # 4 is approximately the head at the design operating point! "5"
#Times“
%#&! The 0 $curve is also a steep descent curve! When! 14% effluent
When the gate valve is closed&! Therefore, the axial flow pump should
+Opening and starting“
%$&! 0 The curve takes on a hump shape! The scope of efficient work
Very small, therefore! Axial flow pumps should not use gate valves to regulate flow! Avoid
The axial flow pump usually uses variable angle adjustment to change the flow rate, which is achieved by changing the blade device angle
%To change its performance curve, large fully adjustable axial flow pumps usually close the blades before starting to reduce the starting power of the pump
The% angle of the piece! Gradually increase the% angle after startup! This way! It fully utilizes the characteristics of fully adjustable axial flow pumps“
%The suction performance of the 0&axial flow pump is poor! The installation height is generally negative. When designing the installation height, careful consideration must be given to the shaft
The inlet conditions of the flow pump include the submergence depth of the suction port, the shape of the suction channel, etc! The actual operating point during operation is related to the pump design
Calculate the degree of deviation from the operating point! The manufacturing quality of impeller blade shape and water pump installation quality, etc! Avoid operating in axial flow pumps
Part produces cavitation“
%The specific speed of the 5&axial flow pump is relatively high! Usually used in situations with high flow rate and low head! For example, in a large steel plant # thermal power generation
The circulating water pump station of the thermal power plant! Urban Rainwater Flood Control Pump Station # Large Sewage Pump Station and One of the Long Distance Water Transportation Projects
Some large lifting pump stations and other axial flow pumps generally have a head of only 0! Around 5&“
Two! Mixed flow pump
A mixed flow pump is a type of pump located between a centrifugal pump and an axial flow pump! The force acting on the liquid particles in the pump body includes centrifugal force!
There is axial lift again! The water flow direction of the impeller outlet is oblique, which can be divided into volute type and volute type according to the different pressure chambers
There are two types of guide vanes! Among them, the snail shell type is widely used. From the appearance, the snail shell mixed flow pump is similar to the single suction centrifugal pump!
As shown in Figure # 3# The guide vane mixed flow pump shown is similar to a vertical axial flow pump! As shown in Figure # 3$ The components of these two mixed flow pumps are not available
What a big difference! The only difference is the shape of the impeller and the support method of the pump body. Mixed flow pumps are suitable for factories, mines, and cities
Water drainage and farmland irrigation, etc“