The function and requirements of the axial pump suction chamber are the same as those of the centrifugal pump. 1 Water is introduced into the impeller suction port. The hydraulic loss in the suction chamber is small. When the liquid enters the impeller suction port from the suction chamber, the velocity distribution should be uniform.
The hydraulic loss in the suction chamber of the axial flow pump is small because the flow rate in the suction chamber of the axial flow pump is generally low. Therefore, when the flow velocity distribution is uneven, the hydraulic loss is not large, but since the head of the axial flow pump is also low, the hydraulic loss in the suction chamber still accounts for a certain ratio from the viewpoint of hydraulic efficiency. Uneven velocity distribution in the axial pump suction chamber will destroy the regularity of the relative flow and reduce the hydraulic efficiency and cavitation performance of the impeller.
Therefore, when designing the suction chamber of the axial flow pump, it is required that the axial flow size should be as small as possible (the distance between the pump station unit and the unit can be small, and the construction area of the pump house can be reduced), and the flow enters the impeller shaft. The surface velocity is substantially uniform, and the circumferential component of the absolute velocity is required to be sufficiently small that the requirements are small enough to be neglected. Therefore, after designing the suction chamber of the axial flow pump, a hydraulic test should be performed.
The suction chambers of several axial flow pumps are described below.
1. Suction tube
The upper end of the suction horn is connected to the impeller chamber. This is the simplest and most hydraulic suction chamber. The velocity of the liquid is evenly distributed after being sucked into the horn. However, this suction chamber can only be applied to medium and small axial flow pumps, and is generally only used for axial flow pumps with impeller diameter D < 1 m.
The suction bell tube absorbs water from the sump, and the position of the suction tube in the sump and the minimum water level have certain requirements to prevent the Fengqi neighboring suction tube from affecting each other, preventing the occurrence of the vortex tube and preventing the air from being inhaled.
If the suction bellows separately absorbs water from the sump, the sump can be made rectangular and the liquid has no free surface in the sump.
2. Elbow suction chamber
The elbow suction chamber is the suction chamber used for large axial flow pumps, which are most commonly used in large axial flow pumping stations. This suction chamber can be divided into three parts, namely a suction port portion, an elbow portion, and a conical tube portion. From the suction port to the elbow outlet, the flow cross section must be completely contracted, and the elbow portion is also required to contract faster.
If the elbow suction chamber is newly designed according to the specific conditions of the pump station geology, the model experiment can be carried out on the wind tunnel after design, and the better results can be used. If there is a pier in the middle, it is more important to note that although the pier is placed in the middle of the inlet, due to the different flow directions of the rice, vortices will be generated at the pier, and the flow on both sides of the pier will be unequal, so the hydraulic performance of the suction chamber will decrease.
3. Bell shaped suction chamber
The bell-type suction chamber is applied to a large axial flow pump, which is small in height but wider in width than the elbow-shaped suction chamber, and is not rectangular but circular. The bottom of the bell-shaped suction chamber has a water guiding cone, and the outlet of the suction chamber is connected with the impeller chamber. The shape of the connecting portion is a bell tube shape, and the liquid self-conducting water cone and the bell tube are guided into the impeller, so if the water guiding cone flows around The juice is good, and the suction chamber can get good hydraulic performance, that is, the hydraulic loss is small and the velocity distribution is uniform.
The design of the bell-type suction chamber, the greater the height of the bell tube, the better the hydraulic performance.
