Method for improving flow pattern of effluent water flow of urban drainage pump station with facade double-layer arrangement form

Abstract

The application discloses a method for improving the flow state of discharged water flow of a facade double-layer arrangement type urban drainage pump station, and the method is characterized in that: a plurality of flat plates are arranged between the upper and lower pump rooms of the drainage pump station to play a role of energy dissipation on the discharged water flow of the upper pump room; a flow distribution ridge and a flow guide pier are arranged on the first flat plate to play a role of improving the uniformity of flow distribution and improving the uniformity of flow velocity distribution of the discharged water flow; and a flow blocking ridge with a slotted bottom is arranged at the water outlet end of each flat plate, which is beneficial to forming uniform and gentle falling water flow to reduce the hydraulic impact on the flat plate and prevent the accumulation at the bottom of the flat plate. The application can effectively dissipate the energy of the discharged water flow of the facade double-layer arrangement type urban drainage pump station and improve the flow state of the water flow, has good engineering application value for ensuring the structural safety and operation stability of the facade double-layer arrangement type urban drainage pump station, and is also suitable for popularization and use in design and reconstruction engineering of facade multi-layer arrangement type drainage pump stations and other discharge buildings.

Description

Technical Field

[0001] The invention relates to the technical field of urban drainage pump station engineering, in particular to a method for improving the flow pattern of downstream water flow in an urban drainage pump station with a double-layer facade arrangement. Background Art

[0002] my country has entered a period of accelerated urban development, but population density and industrial agglomeration have brought many adverse impacts to cities. Urban flooding and deteriorating water environments are becoming increasingly prominent. As a critical piece of urban infrastructure, drainage systems are primarily responsible for treating and removing urban sewage and rainwater. In the construction of municipal engineering and environmental governance projects, the rational design of urban drainage systems while meeting various technical requirements is a key component of current urban planning and design in my country.

[0003] As a core component of urban drainage systems, drainage pumping stations are often subject to external constraints during their design and construction, such as site area, underground pipe network layout, and surrounding existing buildings. This results in a compact structure and often makes it difficult to arrange them in a manner that ensures optimal water inflow conditions. This sometimes necessitates designing and operating two pump houses in a double-layered, vertical layout. Due to the significant height difference between the upper and lower pump houses, if the outflow from the upper pump house directly falls into the lower pump house, it can easily generate high-speed impact water flow, which not only affects the structural safety of the lower pump house but also compromises the inflow conditions, affecting the operating efficiency and stability of the pump units. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to address the deficiencies of the above-mentioned prior art and to provide a method for improving the flow state of the downstream water flow of an urban drainage pump station with a double-layer facade layout. The method for improving the flow state of the downstream water flow of an urban drainage pump station with a double-layer facade layout can effectively dissipate the energy of the downstream water flow of the upper pump room while improving the uniformity of the flow velocity distribution of the downstream water flow, thereby improving the flow state of the downstream water flow from the upper pump room into the lower pump room, which helps to ensure the structural safety of the lower pump room and the high efficiency and stability of the water pump unit operation.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0006] A method for improving the flow pattern of water discharged from a double-layer facade urban drainage pump station comprises the following steps.

[0007] Step 1: Forming a downstream water flow: The urban drainage pump station has a lower pump house and an upper pump house vertically arranged on the top of the lower pump house; water flows out of the upper pump house to form a downstream water flow and enter the lower pump house.

[0008] Step 2, first-stage energy dissipation: a stepped multi-stage energy dissipation plate is set at the bottom of the pool of the lower pump room; the multi-stage energy dissipation plate includes a first-stage energy dissipation plate, a second-stage energy dissipation plate, ..., an N-stage energy dissipation plate with gradually decreasing heights; wherein; N ≥ 3.

[0009] The downstream water flow entering the lower pump room falls onto the horizontally set first-stage energy dissipation plate to achieve the first-stage energy dissipation.

[0010] Step 3, rectification: by setting diversion sill and guide pier on the top of the first-stage energy dissipation plate, the flow distribution uniformity of the downstream water flow in the first-stage energy dissipation process is improved and the flow velocity distribution uniformity of the downstream water flow is improved.

[0011] Step 4, first-stage water retaining: by setting a water retaining sill with a bottom slot at the outlet end of the first-stage energy dissipation plate, the downstream water flow after the first-stage energy dissipation forms a uniform and gentle falling water flow, so as to reduce the hydraulic impact on the second-stage energy dissipation plate and prevent siltation at the bottom of the first-stage energy dissipation plate.

[0012] Step 5, second-stage energy dissipation: The falling water flow in step 4 falls onto the horizontally arranged second-stage energy dissipation plate to achieve second-stage energy dissipation.

[0013] Step 6, second-stage water retaining: A water retaining sill with a bottom slot is set at the outlet end of the second-stage energy dissipation plate, so that the downstream water flow after the second-stage energy dissipation forms a uniform and gentle falling water flow, thereby reducing the hydraulic impact on the third-stage energy dissipation plate and preventing siltation at the bottom of the second-stage energy dissipation plate.

[0014] Step 7. Repeat steps 5 and 6 to achieve the Nth level of energy dissipation, and the downstream water flow after the Nth level of energy dissipation forms a uniform and gentle falling water flow to reduce the hydraulic impact on the next level of energy dissipation plate or the bottom of the lower pump room pool and prevent siltation at the bottom of the current level of energy dissipation plate.

[0015] In steps 2 and 7, the calculation formula for the number of energy dissipation plates N is:

[0016] N=INT(H÷2.5)

[0017] Among them, INT function is the rounding function; H is the total height of the lower pump room.

[0018] In step 1, the width of the lower pump room is W, the height is H, and the length is L; the width of the upper pump room is W1 and W1=(1.0~2.0)W, and the height is H3 and H3=(0.4~0.6)H.

[0019] In step 2, the distance between the first-stage energy dissipation plate and the bottom surface of the upper pump room is H8, and H8 = (0.15 ~ 0.2) H. The distance between the lowest-level energy dissipation plate and the bottom surface of the lower pump room and the distance between adjacent energy dissipation plates are both H9, and H9 = (H - H8) ÷ N. The width of each level of energy dissipation plate is W5, and W5 = W. The length of the first-level energy dissipation plate is L5, and L5 = (0.5 ~ 0.6) W1. The length of the other levels of energy dissipation plates is L6, and L6 = (0.3 ~ 0.4) W1.

[0020] In step 3, a diverter sill is set in the middle of the first-stage energy dissipation plate, one end of the diverter sill is connected to the corresponding water retaining sill, and the other end is connected to the rear wall of the first-stage energy dissipation plate. The height of the diverter sill is B7 and B7=(0.2~0.3)H8; the first-stage energy dissipation plate is provided with a guide pier, the length of the guide pier is L7 and L7=(0.4~0.6)L5, the height is B8 and B8=(0.15~0.25)H8, the width of the diverter sill and the guide pier is C4 and C4=(0.02~0.03)W, the distance between the guide pier and the adjacent side wall of the energy dissipation plate is C5 and C5=(0.2~0.25)W, and the distance between the guide pier and the rear wall is C6 and C6=(0.4~0.5)L5.

[0021] In steps 4, 6 and 7, connected vertical retaining walls are set between adjacent energy dissipation plates; water retaining sills are set at the water outlet ends of each level of energy dissipation plates, the bottom of the water retaining sills are slit and the two ends are respectively connected to the vertical retaining walls on both sides of the corresponding energy dissipation plates; the cross-section of each water retaining sill is rectangular, the height of the rectangular cross-section is B5 and B5=(0.1~0.15)H9, the width of the rectangular cross-section is W6 and W6=(0.03~0.08)L6, and the gap height at the bottom of the water retaining sill is B6 and B6=(0.02~0.04)H9.

[0022] The number of water pump units in the lower pump room is N1 and N1 = (2 to 4). Partition piers are set between adjacent water pump units in the lower pump room. The width of the partition pier is B1 and B1 = (0.02 to 0.1)W, the length is C1 and C1 = (0.2 to 0.4)L, the height is H1 and H1 = (0.1 to 0.2)H. The distance between the water pump unit in the lower pump room and the rear wall of the lower pump room is C2 and satisfies C2 = (0.1 to 0.2)L, and the distance between the water pump unit and the two side walls is B2 and satisfies B2 = [W - (N1 - 1) × B1] ÷ (2 × N1). The height between the water surface of the lower pump room and its bottom surface is H2 and H2 = (0.3 to 0.6)H.

[0023] The number of water pump units in the upper pump room is N2 and N2 = (2 ~ 4), the distance between the water pump side unit in the upper pump room and its adjacent side wall is B3 and B3 = (0.1 ~ 0.15) W1, the distance between the water pump units in adjacent upper pump rooms is B4 and B4 = (W1 - 2 × B3) ÷ (N2 - 1), the distance between the rear side wall of the upper pump room and the water pump unit is C3 and C3 = (0.1 ~ 0.2) L, the rear side wall of the upper pump room and the side wall of the lower pump room are in the same plane.

[0024] The bottom height of the water outlet pool of the upper pump room is the same as the bottom height of the upper pump room. The length of the water outlet pool is L1 and L1=W1, the height is H4 and H4=H3, the width is W2 and W2=(0.4-0.6)W, the number of water outlets opened in the water outlet pool is N3 and N3=N2, the outlet pipe of the water pump unit in the upper pump room vertically passes through the rear wall of the pump room and is opposite to the outlet of the water outlet pool, and the outlet pipe of the water pump unit in the upper pump room is The height from the center to the bottom of the water outlet pool is H5 and H5 = (0.6 ~ 0.8) H3, the distance from the water outlet of the water outlet pool is L2 and L2 = (0.7 ~ 0.8) W2, the length of the rectangular cross-section of the water outlet of the water outlet pool is L3 and L3 = (0.15 ~ 0.2) L1, the width is W3 and W3 = (0.1 ~ 0.15) H4, and the height from the center of the water outlet of the water outlet pool to the bottom surface is H6 and H6 = H5.

[0025] An outlet gallery is provided in the upper pump room. The water flow of the upper pump room enters the outlet gallery through the outlet of the outlet pool, and then falls into the multi-stage energy dissipation plate. The length of the outlet gallery is L4 and L4=W1, the width is W4 and W4=(0.2~0.3)W, and the height is H7 and H7=H3.

[0026] The present invention has the following beneficial effects:

[0027] 1. The multi-stage energy dissipation plate can dissipate energy of the water discharged from the upper pump room. By setting diverter sills and diversion piers on the first-stage plate, the uniformity of the flow distribution of the discharged water and the uniformity of the flow velocity distribution of the discharged water can be improved. By setting water retaining sills with bottom slits at the water outlet of each stage of the energy dissipation plate, it is conducive to forming a uniform and gentle falling water flow to reduce its hydraulic impact on the energy dissipation plate and prevent siltation at the bottom of the energy dissipation plate.

[0028] 2. The structural design adopted by the present invention is simple and easy to construct. It can effectively dissipate energy and improve the flow state of the discharged water from the urban drainage pump station with a double-layer facade layout. It has good engineering application value for ensuring the structural safety and operational stability of the urban drainage pump station with a double-layer facade layout. It is also suitable for promotion and use in the design and renovation projects of drainage pump stations with multi-layer facade layouts and other drainage buildings. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A plan view of the urban drainage pump station of the present application is shown.

[0030] Figure 2 A plan view of the urban drainage pump station of the present application is shown.

[0031] Figure 3 A plan view of the urban drainage pump station of the present application is shown.

[0032] Figure 4 A plan view of the urban drainage pump station of the present application is shown.

[0033] Figure 5 A plan view of the urban drainage pump station of the present application is shown.

[0034] The urban drainage pump station of the present application comprises: 1. a lower pump house; 2. a water pump unit in the lower pump house; 3. an upper pump house; 4. a water pump unit in the upper pump house; 5. a water outlet pool in the upper pump house; 6. a water outlet corridor; 7. a multi-stage energy dissipation plate; 7A. a first stage energy dissipation plate; 7B. a bottom energy dissipation plate; 8. a partition pier in the lower pump house; 9. a water outlet in the water outlet pool in the upper pump house; 10. a flow dividing baffle; 11. a flow guiding pier; 12. a slotted water retaining baffle; and 13. a vertical retaining wall. DETAILED DESCRIPTION

[0035] The present application will be further described in detail below with reference to the accompanying drawings and specific preferred embodiments.

[0036] In the description of the present application, it should be understood that the terms "left side", "right side", "upper part", "lower part" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and "first", "second" and the like do not represent the importance of the parts, and therefore cannot be understood as limiting the present application. The specific dimensions used in the embodiments are only for the purpose of illustrating the technical solutions and do not limit the protection scope of the present application.

[0037] A method for improving the flow pattern of the discharged water flow of the urban drainage pump station of the present application, comprising the following steps.

[0038] Step 1, forming a discharged water flow

[0039] As shown in Figures 1 to 4 The urban drainage pump station has a lower pump house 1 and an upper pump house 3 arranged vertically on the top of the lower pump house. The water flow in the upper pump house forms a discharged water flow through the water outlet of the water outlet pool at the bottom or one side, and enters the lower pump house.

[0040] The width of the lower pump room 1 is W, the height is H, and the length is L. The number of water pump units 2 in the lower pump room is N1, and N1 = (2 to 4). A partition pier 8 is set between adjacent water pump units. The width of the partition pier 8 is B1, and B1 = (0.02 to 0.1)W, the length is C1, and C1 = (0.2 to 0.4)L, and the height is H1, and H1 = (0.1 to 0.2)H. The distance between the water pump unit 2 in the lower pump room and the rear wall of the lower pump room 1 is C2, and C2 = (0.1 to 0.2)L. The distance between the water pump unit 2 and the two side walls is B2, and B2 = [W-(N1-1)×B1]÷(2×N1). The height between the water surface of the lower pump room and its bottom surface is H2, and H2 = (0.3 to 0.6)H.

[0041] The width of the upper pump room 3 is W1 and W1=(1.0~2.0)W, the height is H3 and H3=(0.4~0.6)H, the number of water pump units 4 in the upper pump room is N2 and N2=(2~4), the distance between the water pump side unit 4 and its adjacent side wall in the upper pump room is B3 and B3=(0.1~0.15)W1, the distance between adjacent water pumps is B4 and B4=(W1-2×B3)÷(N2-1), the distance between the rear side wall of the upper pump room 3 and the water pump unit 4 is C3 and C3=(0.1~0.2)L, and the rear side wall of the upper pump room 3 and the side wall of the lower pump room 1 are in the same plane.

[0042] The bottom height of the upper pump room outlet pool 5 is the same as the bottom height of the upper pump room 3. The length of the outlet pool 5 is L1 and L1=W1, the height is H4 and H4=H3, the width is W2 and W2=(0.4-0.6)W, the number of water outlets 9 provided in the outlet pool 5 is N3 and N3=N2, the outlet pipe of the upper pump room water pump unit 4 vertically passes through the rear wall of the pump room and is opposite to the outlet pool outlet 9, and the outlet pipe of the upper pump room water pump unit 4 is The height from the center of the outlet to the bottom of the water outlet pool 5 is H5 and H5 = (0.6 ~ 0.8) H3, the distance from the outlet 9 of the water outlet pool is L2 and L2 = (0.7 ~ 0.8) W2, the length of the rectangular cross-section of the outlet 9 of the water outlet pool is L3 and L3 = (0.15 ~ 0.2) L1, the width is W3 and W3 = (0.1 ~ 0.15) H4, and the height from the center of the outlet 9 of the water outlet pool to the bottom is H6 and H6 = H5.

[0043] The length of the upper outlet gallery 6 is L4 and L4=W1, the width is W4 and W4=(0.2-0.3)W, and the height is H7 and H7=H3.

[0044] Step 2: First-level energy dissipation

[0045] A stepped multi-stage energy dissipation plate is provided at the bottom of the pool of the lower pump room; the multi-stage energy dissipation plate comprises a first stage energy dissipation plate, a second stage energy dissipation plate, ..., an Nth stage energy dissipation plate of gradually decreasing heights; wherein; N ≥ 3.

[0046] The downstream water flow entering the lower pump room falls onto the horizontally set first-stage energy dissipation plate to achieve the first-stage energy dissipation.

[0047] The number of the above-mentioned energy dissipation plates 7 is preferably N and N=INT(H÷2.5), wherein the INT function is a rounding function, the distance between the first-stage energy dissipation plate 7A and the bottom surface of the upper pump room 3 is H8 and H8=(0.15~0.2)H, the distance between the lowest-level energy dissipation plate 7B and the bottom surface of the lower pump room 1 and the distance between adjacent energy dissipation plates 7 are both H9 and H9=(H-H8)÷N, the width of each level of energy dissipation plate 7 is W5 and W5=W, the length of the first-stage energy dissipation plate 7A is L5 and L5=(0.5~0.6)W1, and the length of the other levels of energy dissipation plates is L6 and L6=(0.3~0.4)W1.

[0048] Step 3, rectification: by setting diversion sill and guide pier on the top of the first-stage energy dissipation plate, the flow distribution uniformity of the downstream water flow in the first-stage energy dissipation process is improved and the flow velocity distribution uniformity of the downstream water flow is improved.

[0049] A diverter sill 10 is provided in the middle of the first-stage energy dissipation plate 7A, one end of the diverter sill 10 is connected to the corresponding water retaining sill 12, and the other end is connected to the rear wall of the first-stage energy dissipation plate 7A. The height of the diverter sill 10 is B7 and B7=(0.2~0.3)H8. The first-stage energy dissipation plate 7A is provided with a guide pier 11, the length of the guide pier 11 is L7 and L7=(0.4~0.6)L5, the height is B8 and B8=(0.15~0.25)H8, the width of the diverter sill 10 and the guide pier 11 are both C4 and C4=(0.02~0.03)W, the distance between the guide pier 11 and the adjacent side wall of the energy dissipation plate is C5 and C5=(0.2~0.25)W, and the distance between the guide pier 11 and the rear wall is C6 and C6=(0.4~0.5)L5.

[0050] Step 4, first-stage water retaining: by setting a water retaining sill with a bottom slot at the outlet end of the first-stage energy dissipation plate, the downstream water flow after the first-stage energy dissipation forms a uniform and gentle falling water flow, so as to reduce the hydraulic impact on the second-stage energy dissipation plate and prevent siltation at the bottom of the first-stage energy dissipation plate.

[0051] A connected vertical retaining wall 13 is set between adjacent energy dissipation plates. A water retaining sill 12 with a bottom slit and two ends connected to the side walls of the energy dissipation plates is set at the water outlet end of each level of energy dissipation plates. The cross-section of the water retaining sill 12 is rectangular, the height of the rectangular cross-section is B5 and B5=(0.1~0.15)H9, the width of the rectangular cross-section is W6 and W6=(0.03~0.08)L6, and the gap height at the bottom of the water retaining sill is B6 and B6=(0.02~0.04)H9.

[0052] Step 5, second-stage energy dissipation: The falling water flow in step 4 falls onto the horizontally arranged second-stage energy dissipation plate to achieve second-stage energy dissipation.

[0053] Step 6, second-stage water retaining: A water retaining sill with a bottom slot is set at the outlet end of the second-stage energy dissipation plate, so that the downstream water flow after the second-stage energy dissipation forms a uniform and gentle falling water flow, thereby reducing the hydraulic impact on the third-stage energy dissipation plate and preventing siltation at the bottom of the second-stage energy dissipation plate.

[0054] Step 7. Repeat steps 5 and 6 to achieve the Nth level of energy dissipation, and the downstream water flow after the Nth level of energy dissipation forms a uniform and gentle falling water flow to reduce the hydraulic impact on the next level of energy dissipation plate or the bottom of the lower pump room pool and prevent siltation at the bottom of the current level of energy dissipation plate.

[0055] The following describes the effects of the implementation of the present invention in detail with reference to specific embodiments.

[0056] Example

[0057] The width W of the lower pump room is 8.4m, the height H is 12m, and the length L is 15m. The number of pump units in the lower pump room is N1, which is 2. The width B1 of the partition pier between adjacent pump units is 0.4m, the length C1 is 4.3m, and the height H1 is 1.5m. The distance C2 between the pump unit in the lower pump room and the rear wall of the pump room is 2m, and the distance B2 between the pump unit and the two side walls is 2m. The height H2 between the water surface and the bottom surface of the lower pump room is 3.6m. The width W1 of the upper pump room is 10m, the height H3 is 6m, and the number of pump units in the upper pump room is 1. The number N2 is 4, the distance B3 between the water pump side unit of the upper pump room and its adjacent side wall is 1.25m, the distance B4 between adjacent water pumps is 2.5m, the distance C3 between the rear wall of the upper pump room and the water pump unit is 1.5m, the length L1 of the outlet pool is 10m, the height H4 is 6m, and the width W2 is 4.2m. The number of outlets opened in the outlet pool is N3 4, the height H5 between the center of the outlet pipe of the water pump unit of the upper pump room and the bottom of the outlet pool is 4m, and the distance L2 from the outlet of the outlet pool is 3.2m. The outlet of the outlet pool has a rectangular cross-section. The length L3 is 1.7m, the width W3 is 0.8m, the height H6 from the center of the outlet of the water outlet pool to the bottom is 4m, the length L4 of the upper outlet gallery is 10m, the width W4 is 2m, and the height H7 is 6m. The number of energy dissipation plates N is 5, the distance H8 between the first-level energy dissipation plate and the bottom of the upper pump room is 2m, the distance H9 between the lowest-level energy dissipation plate and the bottom of the lower pump room and the distance between adjacent energy dissipation plates is 2m, the width W5 of each level of energy dissipation plate is 8.4m, and the length L5 of the first-level energy dissipation plate is 5.5 m, the length L6 of the energy dissipation slabs at other levels is 3.5m, the height B5 of the rectangular cross-section of the water retaining slab is 0.25m, the width W6 is 0.18m, the height B6 of the gap at the bottom of the flow retaining slab is 0.05m, the height B7 of the diverter slab in the middle of the first-stage energy dissipation slab is 0.5m, the length L7 of the diversion pier of the first-stage energy dissipation slab is 2.6m, the height B8 is 0.4m, the width C4 between the diverter slab and the diversion pier is 0.2m, the distance C5 between the diversion pier and the adjacent side wall of the energy dissipation slab is 2m, and the distance C6 between the diversion pier and the rear wall is 2.4m.

[0058] Implementation effect evaluation

[0059] like Figure 5 As shown, a three-dimensional flow numerical simulation method is used to compare and analyze the flow velocity distribution uniformity of the inlet section of the water pump unit of the lower pump room of the urban drainage pump station with a double-layer facade arrangement according to the above embodiment of the present invention. The flow velocity distribution uniformity V u The calculation expression is as follows:

[0060]

[0061] Among them, V is the average flow velocity of the water pump inlet section of the lower pump room, V iis the flow velocity of the i-th measuring point on the inlet section of the pump unit in the lower pump room, n is the number of flow velocity measuring points, and for the flow velocity distribution uniformity V u The closer the value is to 100%, the more uniform the flow velocity distribution along the mainstream direction is.

[0062] according to Figure 5 It can be seen that the inflow velocity distribution uniformity V of the water pump unit in the lower pump room of the urban drainage pump station in the double-layer layout form after rectification of the present invention is u It is significantly improved, which shows that the present invention can significantly improve the flow state of the discharged water from the urban drainage pump station with a double-layer facade arrangement, thereby helping to ensure the safety and stability of the operation of the urban drainage pump station.

[0063] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various equivalent transformations can be made to the technical solutions of the present invention, and these equivalent transformations all fall within the scope of protection of the present invention.

Claims

1. A method for improving the flow pattern of water discharged from a double-layer urban drainage pump station, characterized by: The steps include: Step 1: Forming a downstream water flow: The urban drainage pump station has a lower pump house and an upper pump house vertically arranged on top of the lower pump house; water flows out of the upper pump house to form a downstream water flow, which flows into the lower pump house; Step 2, first-stage energy dissipation: a stepped multi-stage energy dissipation plate is set at the bottom of the pool in the lower pump room; the multi-stage energy dissipation plate includes a first-stage energy dissipation plate, a second-stage energy dissipation plate, ..., an N-stage energy dissipation plate of gradually decreasing height; where N ≥ 3, and the calculation formula for the number of energy dissipation plates N is: N=INT(H÷2.5) Among them, INT function is the rounding function; H is the total height of the lower pump room; The water flow entering the lower pump room falls onto the horizontally arranged first-stage energy dissipation plate to achieve the first-stage energy dissipation; Step 3, rectification: by setting the diversion sill and the guide pier on the top of the first-stage energy dissipation plate, the flow distribution uniformity of the downstream water flow in the first-stage energy dissipation process is improved and the flow velocity distribution uniformity of the downstream water flow is improved; Step 4, first-stage water retaining: by setting a water retaining sill with a slot at the bottom at the outlet end of the first-stage energy dissipation plate, the downstream water flow after the first-stage energy dissipation forms a uniform and gentle falling water flow, thereby reducing the hydraulic impact on the second-stage energy dissipation plate and preventing siltation at the bottom of the first-stage energy dissipation plate; Connected vertical retaining walls are set between adjacent energy dissipation slabs; water retaining sills are set at the water outlet of each energy dissipation slab, with a slit at the bottom of the water retaining sill and both ends connected to the vertical retaining walls on both sides of the corresponding energy dissipation slab; the cross section of each water retaining sill is rectangular, and the height of the rectangular cross section is B5, and B5 = (0.1~0.15) H9; Step 5, second-stage energy dissipation: The falling water flow in step 4 falls onto the horizontally arranged second-stage energy dissipation plate to achieve second-stage energy dissipation; Step 6, second-stage water retaining: a water retaining sill with a bottom slot is set at the outlet end of the second-stage energy dissipation plate, so that the downstream water flow after the second-stage energy dissipation forms a uniform and gentle falling water flow, thereby reducing the hydraulic impact on the third-stage energy dissipation plate and preventing siltation at the bottom of the second-stage energy dissipation plate; Step 7. Repeat steps 5 and 6 to achieve the Nth level of energy dissipation, and the downstream water flow after the Nth level of energy dissipation forms a uniform and gentle falling water flow to reduce the hydraulic impact on the next level of energy dissipation plate or the bottom of the lower pump room pool and prevent siltation at the bottom of the current level of energy dissipation plate.

2. The method for improving the flow pattern of the outflow of the urban drainage pump station with a double-layer facade layout according to claim 1 is characterized by: In step 1, the width of the lower pump room is W, the height is H, and the length is L; the width of the upper pump room is W1 and W1=(1.0~2.0)W, and the height is H3 and H3=(0.4~0.6)H.

3. The method for improving the flow pattern of the outflow from a double-layer urban drainage pump station according to claim 2, characterized in that: In step 2, the distance between the first-stage energy dissipation plate and the bottom surface of the upper pump room is H8, and H8=(0.15~0.2)H; the distance between the lowest-level energy dissipation plate and the bottom surface of the lower pump room and the distance between adjacent energy dissipation plates are H9, and H9=(H-H8)÷N; the width of each level of energy dissipation plate is W5, and W5=W; the length of the first-level energy dissipation plate is L5, and L5=(0.5~0.6)W1; the length of the energy dissipation plates at other levels is L6, and L6=(0.3~0.4)W1.

4. The method for improving the flow pattern of the outflow from a double-layer urban drainage pump station according to claim 3 is characterized in that: In step 3, a diverter sill is set in the middle of the first-stage energy dissipation plate, one end of the diverter sill is connected to the corresponding water retaining sill, and the other end is connected to the rear wall of the first-stage energy dissipation plate. The height of the diverter sill is B7 and B7=(0.2~0.3)H8; the first-stage energy dissipation plate is provided with a diversion pier, the length of the diversion pier is L7 and L7=(0.4~0.6)L5, the height is B8 and B8=(0.15~0.25)H8, the width of the diverter sill and the diversion pier is C4 and C4=(0.02~0.03)W, the distance between the diversion pier and the adjacent side wall of the energy dissipation plate is C5 and C5=(0.2~0.25)W, and the distance between the diversion pier and the rear wall is C6 and C6=(0.4~0.5)L5.

5. The method for improving the flow pattern of the outflow from a double-layer urban drainage pump station according to claim 4 is characterized in that: In steps 4, 6, and 7, the width of the rectangular cross section of each water retaining sill is W6, and W6=(0.03-0.08)L6, and the height of the gap at the bottom of the water retaining sill is B6, and B6=(0.02-0.04)H9.

6. The method for improving the flow pattern of the outflow from a double-layer urban drainage pump station according to claim 2, characterized in that: The number of water pump units in the lower pump room is N1 and N1=(2~4). Partition piers are set between adjacent water pump units in the lower pump room. The width of the partition pier is B1 and B1=(0.02~0.1)W, the length is C1 and C1=(0.2~0.4)L, the height is H1 and H1=(0.1~0.2)H. The distance between the water pump unit in the lower pump room and the rear wall of the lower pump room is C2 and satisfies C2=(0.1~0.2)L, and the distance between the water pump unit and the two side walls is B2 and satisfies B2=[W-(N1-1)×B1]÷(2×N1). The height between the water surface of the lower pump room and its bottom surface is H2 and H2=(0.3~0.6)H.

7. The method for improving the flow pattern of the outflow from a double-layer urban drainage pump station according to claim 6, characterized in that: The number of water pump units in the upper pump room is N2 and N2=(2~4), the distance between the water pump side unit in the upper pump room and its adjacent side wall is B3 and B3=(0.1~0.15)W1, the distance between the water pump units in adjacent upper pump rooms is B4 and B4=(W1-2×B3)÷(N2-1), the distance between the rear side wall of the upper pump room and the water pump unit is C3 and C3=(0.1~0.2)L, the rear side wall of the upper pump room and the side wall of the lower pump room are in the same plane.

8. The method for improving the flow pattern of the outflow from a double-layer urban drainage pump station according to claim 7, characterized in that: The bottom height of the outlet pool of the upper pump room is the same as that of the upper pump room. The length of the outlet pool is L1 and L1=W1, the height is H4 and H4=H3, the width is W2 and W2=(0.4~0.6)W, the number of outlets in the outlet pool is N3 and N3=N2, the outlet pipe of the water pump unit in the upper pump room passes vertically through the rear wall of the pump room and faces the outlet of the outlet pool. The outlet pipe of the water pump unit in the upper pump room is The height from the center to the bottom of the water outlet pool is H5 and H5=(0.6~0.8)H3, the distance from the water outlet of the water outlet pool is L2 and L2=(0.7~0.8)W2, the length of the rectangular cross-section of the water outlet of the water outlet pool is L3 and L3=(0.15~0.2)L1, the width is W3 and W3=(0.1~0.15)H4, and the height from the center of the water outlet of the water outlet pool to the bottom is H6 and H6=H5.

9. The method for improving the flow pattern of the outflow from a double-layer urban drainage pump station according to claim 8, characterized in that: An outlet gallery is provided in the upper pump room. The water flow of the upper pump room enters the outlet gallery through the outlet of the outlet pool, and then falls into the multi-stage energy dissipation plate. The length of the outlet gallery is L4 and L4=W1, the width is W4 and W4=(0.2~0.3)W, and the height is H7 and H7=H3.

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