A flow control method for suppressing separation vortex on the inner wall of a liquid ring pump

Abstract

The present invention discloses a flow control method for suppressing separation vortices on the inner wall of a liquid ring pump, comprising a housing, an impeller, an exhaust port, and an air intake port. The pressure of the working liquid near the inner wall of the housing in the liquid ring pump gradually increases from the air intake side to the air exhaust side, causing the flow near the inner wall of the pump housing to be a reverse pressure flow, thereby inducing flow separation and causing the pump performance to decrease. The present invention respectively sets a liquid inlet hole and a liquid outlet hole in the high-pressure area and the low-pressure area of ​​the pump, and connects them with a drainage pipe, and the angle between the axis of the liquid outlet hole and the tangent of the inner wall of the housing is less than 13°; the present invention utilizes the internal flow characteristics of the liquid ring pump, and introduces the high-pressure liquid in the high-pressure area into the low-pressure area through the drainage pipe to form a high-speed jet, and suppresses the wall separation flow, so as to improve the hydraulic performance and operation stability of the pump; the present invention realizes effective control of the separation vortex on the wall of the liquid ring pump without injecting additional energy from the outside, without complex devices, and the working liquid maintains an internal circulation state, and there is no additional liquid loss.

Description

Technical Field

[0001] The invention relates to a fluid machinery flow control method, in particular to a flow control method for suppressing separation vortices on the inner wall of a liquid ring pump. Background Art

[0002] Liquid ring pump is a fluid machine that uses liquid as the intermediate medium for energy conversion and is used to pump gas. Due to its advantages such as large air flow, nearly isothermal compression and no rotor metal surface contact, it is widely used in key areas of the national economy such as coal mining, petrochemicals, electricity and aviation. The complex gas-liquid two-phase flow in the pump leads to low efficiency (generally 20% to 50%) and difficulty in performance optimization. The pressure of the working liquid near the inner wall of the shell in the liquid ring pump gradually increases from the suction side to the exhaust side (such as Figure 3 As shown in Figure 2, the liquid near the inner wall of the shell has a large adverse pressure gradient along the flow direction driven by the impeller. During the flow process, the liquid separates from the inner wall of the shell under the action of the adverse pressure gradient to form a wall separation vortex structure (as shown in Figure 2). Figure 4 As shown in the figure, the hydraulic loss in the pump increases and the hydraulic excitation characteristics become complex and changeable, which in turn leads to reduced pump efficiency and operational stability. Summary of the invention

[0003] The technical task of the present invention is to provide a flow control method for suppressing separation vortices on the inner wall of a liquid ring pump in order to solve the above-mentioned deficiencies of the prior art.

[0004] The technical solution adopted by the present invention to solve its technical problems is: a flow control method for suppressing separation vortices on the inner wall of a liquid ring pump, comprising a housing, an impeller, an exhaust port, an air intake port and a drainage pipe of the liquid ring pump; in the liquid ring inside the pump, the exhaust port side close to the inner wall of the housing is a high-pressure area, and the air intake port side close to the inner wall of the housing is a low-pressure area, a liquid inlet hole is provided on the housing in the high-pressure area, and a liquid outlet hole with the same number as the liquid inlet hole is provided on the housing in the low-pressure area, the liquid inlet hole and the liquid outlet hole are connected by a drainage pipe, and the angle between the axis of the liquid outlet hole and the tangent of the housing at the liquid outlet hole is less than 13°.

[0005] Further improvement: the liquid inlet holes are dispersedly arranged on the shell in the high-pressure area, and the liquid outlet holes are dispersedly arranged on the shell in the low-pressure area.

[0006] Further improvement: the drainage tube is arranged in close contact with the outer wall of the shell.

[0007] Further improvement: the diameter of the liquid inlet hole is larger than the diameter of the liquid outlet hole.

[0008] Advantages of the present invention: The present invention utilizes the properties of the liquid ring pump when it is working, sets a plurality of liquid inlet holes in the high-pressure area, sets a plurality of liquid outlet holes in the low-pressure area, and then introduces the high-pressure liquid in the high-pressure area into the low-pressure area through a drainage pipe to form a high-speed jet, through which momentum is injected into the wall separation flow, thereby effectively suppressing the generation and development of wall separation vortexes, thereby improving the hydraulic performance and operation stability of the liquid ring pump; during the whole process, there is no need to inject additional energy from the outside, no need for complex equipment, and the working liquid remains in an internal circulation state, without additional liquid loss, thereby achieving effective control of the liquid ring pump wall separation vortex, thereby achieving the purpose of improving the efficiency and operation stability of the liquid ring pump. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a schematic diagram of the structure of the present invention.

[0010] Figure 2 It is a schematic diagram of the position angle of the liquid outlet of the present invention.

[0011] Figure 3 It is the pressure distribution diagram in the pump of the present invention.

[0012] Figure 4 It is a schematic diagram of the position of the wall separation vortex in the prior art of the present invention.

[0013] Figure 5 It is a comparison diagram of hydraulic performance when the present invention has a drainage tube and when it does not have a drainage tube.

[0014] Figure 6 It is the vortex distribution cloud diagram when there is no drainage tube and when there is a drainage tube in the present invention.

[0015] In the figure: casing 1, impeller 2, exhaust port 3, intake port 4, high pressure area 5, low pressure area 6, liquid inlet hole 7, liquid outlet hole 8, drainage pipe 9, wall separation vortex 10. DETAILED DESCRIPTION

[0016] The present invention is described in detail below with reference to the accompanying drawings.

[0017] like Figure 1As shown, a flow control method for suppressing separation vortices on the inner wall of a liquid ring pump comprises a housing 1 and an impeller 2 of the liquid ring pump, as well as an exhaust port 3 and an air intake port 4; in the liquid ring inside the pump, the fluid near the inner wall of the housing 1 on the side of the exhaust port 3 is a high-pressure area 5, and the fluid near the inner wall of the housing 1 on the side of the air intake port 4 is a low-pressure area 6; a liquid inlet hole 7 is provided on the housing 1 in the high-pressure area 5, and a liquid outlet hole 8 having the same number as the liquid inlet hole 7 is provided on the housing 1 in the low-pressure area 6; wherein the liquid inlet holes 7 are dispersedly arranged on the housing 1 in the high-pressure area 5, and the liquid outlet holes 8 are dispersedly arranged on the housing 1 in the low-pressure area 6, each liquid inlet hole 7 is connected to a corresponding liquid outlet hole 8 through a drainage pipe 9, and the diameter of the liquid inlet hole 7 is greater than the diameter of the liquid outlet hole 8; the drainage pipe 9 can be a metal hose, or the drainage pipe 9 can be directly arranged in contact with the outer wall of the housing, and the angle between the axis of the liquid outlet hole 8 and the tangent of the inner wall of the housing 1 at the liquid outlet hole 8 is less than 13°, so as to enhance the suppression effect of the jet on the wall flow separation.

[0018] Its working principle is: first, a plurality of liquid inlet holes 7 are set in the high-pressure zone 5, and a plurality of liquid outlet holes 8 are set in the low-pressure zone 6, and then the high-pressure liquid in the high-pressure zone 5 is introduced into the low-pressure zone 6 through the drainage tube 9, and the fluid flowing out of the drainage tube 9 forms a high-speed micro-jet, and the high-speed jet generates a velocity component along the mainstream direction near the inner wall of the shell, which is used to inject momentum into the wall separation fluid to inhibit or weaken the formation and development of the wall separation vortex 10, thereby reducing the hydraulic loss and hydraulic excitation force in the liquid ring pump, and improving the efficiency and operation stability of the liquid ring pump; during the whole process, there is no need to inject additional energy from the outside, nor does it require complex equipment, and the working liquid maintains an internal circulation state without additional liquid loss.

[0019] In order to further verify the feasibility of the present invention and the effect of suppressing the wall separation vortex, numerical simulation analysis of the gas-liquid two-phase flow in the liquid ring pump was carried out. During the numerical simulation, the RNG k-ε turbulence model was used to simulate the complex multi-scale turbulent structure in the pump, and the VOF model was used to simulate the gas-liquid two-phase flow in the pump; the gas phase was set as an ideal compressible gas, and the liquid phase was set as 20°C liquid water, considering the influence of gravity and surface tension of the phase interface on the flow field; the sliding grid was used to process the interaction between the rotor and the stator, and the interaction between the pressure field and the velocity field in the pump was coupled using the PISO algorithm; the suction port boundary of the liquid ring pump was set as the mass flow inlet, and the flow rate was set to 0.03kg / s; the exhaust port boundary was set as the pressure outlet, and the outlet pressure was set to the standard atmospheric pressure; the Patch method was used to set a circular ring concentric with the shell as the initial calculation domain of the working fluid in the pump, and in the numerical simulation process, the residual of each parameter was set to 1×10 -5 ; The calculation time step is set to 2×10 -5 s, monitor the inlet vacuum and impeller torque of the liquid ring pump, and when it pulsates periodically and stably, the calculation converges.

[0020] The calculation results are as follows Figure 5 , Figure 6 As shown; Figure 5 is the calculation result of the external characteristics of the pump, where p / p0, N / N0 and η / η0 represent the relative vacuum, relative shaft power and relative efficiency respectively (p, N, η represent the vacuum, power and efficiency with a drainage tube respectively; p0, N0, η0 represent the vacuum, power and efficiency of the original model respectively); it can be seen from the figure that compared with the original model, the vacuum and efficiency of the liquid ring pump with the drainage jet model are improved to a certain extent, among which the efficiency improvement effect is more obvious; the shaft power is reduced to a certain extent. Figure 6 The vorticity distribution of the axial middle section of the liquid ring pump shows that the high vorticity area of ​​the separation vortex on the inner wall of the liquid ring pump housing is significantly reduced after the addition of the drainage tube. The above shows that the flow control method proposed in the present invention has a relatively obvious control effect on the separation vortex on the wall of the liquid ring pump.

[0021] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A flow control method for suppressing separation vortices on the inner wall of a liquid ring pump, comprising a housing, an impeller, an exhaust port and an air intake port of the liquid ring pump, characterized in that: In the liquid ring inside the pump, the exhaust port side close to the inner wall of the shell is a high-pressure area, and the intake port side close to the inner wall of the shell is a low-pressure area. A liquid inlet hole is provided on the shell in the high-pressure area, and a liquid outlet hole with the same number as the liquid inlet hole is provided on the shell in the low-pressure area. The liquid inlet hole and the liquid outlet hole are connected by a drainage pipe, and the angle between the axis of the liquid outlet hole and the tangent of the shell at the liquid outlet hole is less than 13°; the liquid inlet holes are dispersedly arranged on the shell in the high-pressure area, and the liquid outlet holes are dispersedly arranged on the shell in the low-pressure area; the drainage pipe is arranged in contact with the outer wall of the shell; the diameter of the liquid inlet hole is larger than the diameter of the liquid outlet hole.

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