CN-122025210-A - Porous guide plate for improving uniform outlet pressure of grid plate header and design method thereof

Abstract

The invention relates to a porous guide plate for improving uniform outlet pressure of a grid plate header and a design method thereof, and relates to the field of thermal hydraulic design. The liquid sodium coolant pretreatment device comprises a cylindrical guide plate and an inlet small pore plate arranged on the inlet side of the cylindrical guide plate, wherein the cylindrical guide plate is arranged on the upper surface and the lower surface of a grid plate header through a connecting piece, liquid sodium coolant from a main pipeline is pretreated through the inlet small pore plate before entering the cylindrical guide plate, a pre-pressure equalizing cavity is formed between the inlet small pore plate and the cylindrical guide plate and used for diffusing and homogenizing inlet jet flow, and disturbance of inlet drift on a downstream pore area is reduced. The invention aims at the strong disturbance characteristic of the jet flow at the outlet of the main pipeline and the drift flow of the inlet to the downstream pressure field, and the inlet orifice plate is introduced at the inlet to pre-throttle and pre-equalize the pressure of the fluid, so that the influence of the high momentum jet flow at the inlet and the drift flow on the flow distribution in the header is weakened, the uniformity of the distribution of the outlet pressure of the header of the grid plate is improved, and the accuracy and the consistency of the flow distribution of the fuel assembly are improved.

Inventors

• JIANG BIN
• WU HUAZHOU

Assignees

• 哈尔滨工程大学

Dates

Publication Date

20260512

Application Date

20260130

Claims (7)

1. 1. A porous guide plate for improving uniform outlet pressure of a grid plate header is characterized by comprising a cylindrical guide plate and an inlet small hole plate arranged on the inlet side of the cylindrical guide plate, wherein the cylindrical guide plate is arranged on the upper surface and the lower surface of the grid plate header through a connecting piece, liquid sodium coolant from a main pipeline is pretreated through the inlet small hole plate before entering the cylindrical guide plate, and a pre-pressure equalizing cavity is formed between the inlet small hole plate and the cylindrical guide plate and used for diffusing and homogenizing inlet jet flow so as to reduce disturbance of inlet drift flow to a downstream hole area.
2. 2. A porous baffle for elevating a cascade plate header outlet pressure uniformity as recited in claim 1, wherein said inlet orifice plate covers an inlet jet core area having a plurality of inlet orifices therein.
3. 3. A porous baffle for enhancing uniformity of outlet pressure from a cascade plate header as claimed in claim 2, wherein said inlet apertures are arranged in an array or staggered array in a longitudinal and transverse direction with uniform pitch.
4. 4. A porous baffle for enhancing uniformity of outlet pressure of a baffle header according to claim 3, wherein the cylindrical baffle has a hole area which is not circumferentially segmented, a plurality of baffle holes are arranged in the hole area, the baffle holes are uniformly arranged in a uniform aperture arrangement and uniformly arranged according to a predetermined aperture density, so as to provide a main flow capacity under the premise of ensuring a low additional pressure drop, and form a stable flow boundary condition for a downstream outlet pressure field.
5. 5. The porous baffle for elevating uniform outlet pressure of a baffle plate header as set forth in claim 4, wherein the inlet orifice has a diameter D 0 smaller than the diameter D of the baffle hole in the cylindrical baffle plate, and the inlet orifice has an opening ratio lower than the opening ratio of the plate hole area of the cylindrical baffle plate.
6. 6. A porous baffle for enhancing the uniformity of baffle header outlet pressure as set forth in claim 5, wherein said orifice region extends circumferentially to form an annular flow field for achieving uniform coolant discharge and flow straightening over a circumferential extent.
7. 7. A design method for a porous baffle for improving uniform outlet pressure of a grid header, comprising the steps of: According to the geometrical size of the grid plate header, the working condition parameters of primary side liquid sodium and the outlet flow of the reactor core fuel assembly, providing uniformity index and resistance characteristic constraint of the outlet pressure of the grid plate header, determining the position and mounting height of a porous guide plate in the grid plate header and the overall target aperture ratio according to the uniformity index and the resistance characteristic constraint, arranging an inlet small pore plate at the inlet of the large grid plate header, forming a pre-pressure equalizing cavity between the inlet small pore plate and the cylindrical guide plate, and determining the arrangement reference of the porous guide plate along the circumferential direction according to the corresponding direction of the inlet of the main pipeline on the grid plate header; the method comprises the steps of determining a circumferential arrangement reference direction of a cylindrical deflector, uniformly arranging a plurality of deflector holes in the hole area, uniformly arranging the deflector holes in the hole area, determining the number, the hole density and the arrangement mode of the deflector holes according to the overall target opening ratio and the resistance characteristic constraint determined in the step one, so that the cylindrical deflector can provide main through-flow capacity and stable boundary conditions for subsequent pressure equalizing and rectifying on the premise of meeting the pressure drop requirement; step three, according to the main flow direction of liquid sodium in the grid plate header and the distribution characteristics of an initial flow field of an inlet, determining the coverage area of an inlet jet flow core area, arranging an inlet orifice plate at the inlet of a large grid plate header to form a pre-pressure equalizing cavity between the inlet orifice plate and a cylindrical guide plate, and simultaneously determining the aperture diameter, the aperture density and the aperture ratio of the orifice plate to ensure that the equivalent flow capacity of the orifice plate is lower than that of the cylindrical guide plate in the step two, thereby realizing pre-throttling and pre-pressure equalizing of inlet jet flow and weakening the bias flow of the inlet and the disturbance of jet flow to a downstream orifice area on the premise of meeting the restriction of the resistance characteristic in the step one; setting the difference of resistance and flow capacity in the axial direction of the porous guide plate, determining the axial distance between the inlet orifice plate and the cylindrical guide plate to form the cavity depth of the pre-pressure equalizing cavity, and optimizing the parameters of the inlet orifice plate according to the cavity depth and the integral pressure drop constraint; under the condition of containing the baffling small pore plates, the arrangement positions of the baffling small pore plates relative to the cylindrical guide plates and the small pore parameters thereof are further determined, so that the inlet small pore plates, the pre-pressure equalizing cavity, the cylindrical guide plates and the baffling small pore plates form a multi-stage rectifying and pressure drop matching relationship in the axial direction, and the low-pressure loss rectifying and the axial flow balancing in the header are realized on the premise that the integral pressure drop of the grid plate header meets the design requirement; And fifthly, based on the uniform aperture area arrangement scheme of the cylindrical deflector and the inlet orifice parameters, the pre-pressure equalizing cavity depth and the baffling orifice parameters determined in the step two and the step four, checking the flow characteristics and the outlet pressure distribution in the grid plate header by adopting a computational fluid mechanics numerical simulation method, when the pressure non-uniformity of the corresponding positions of the fuel assemblies at the outlet of the grid plate header does not exceed a preset limit value and the integral resistance characteristic change of the grid plate header is within an allowable range, determining the final geometric structure and the installation parameters of the porous deflector for the grid plate header, uniformly arranging the porous deflector in the circumferential direction along the side wall of the header, and if the criteria are not met, returning to adjust the inlet orifice parameters, the pre-pressure equalizing cavity depth or the baffling orifice parameters and repeatedly checking the flow characteristics until the requirements are met.

Description

Porous guide plate for improving uniform outlet pressure of grid plate header and design method thereof Technical Field The invention relates to the field of thermal hydraulic design, in particular to a porous guide plate for improving uniform outlet pressure of a grid plate header and a design method thereof. Background In the fourth generation liquid metal cooled nuclear reactor, the reactor core fuel assemblies are usually connected with the primary loop main pipeline through grid plate headers, and the three-dimensional flow form and outlet pressure distribution inside the grid plate headers directly determine the inlet boundary condition and coolant flow distribution of each fuel assembly, which are key links in the hydraulic design and safety margin evaluation of the reactor core thermal engineering. In engineering design, a one-dimensional or simplified network model is often adopted, the outlet of the grid plate header is approximately uniform average pressure, and flow distribution is carried out by arranging an orifice plate at the inlet of the fuel assembly. Although the method is convenient for engineering realization, the method is difficult to reflect the actual three-dimensional flow structure inside the grid plate header and the local pressure difference at different component positions, so that flow distribution errors can be introduced. Because the grid plate header adopts a lateral inflow mode, complex flow structures such as high momentum jet flow, backflow, secondary flow and the like are easy to form near the outlet of the main pipeline, and a low momentum area and a low flow supply area are easy to appear on one side away from the main pipeline, so that the outlet pressure of the grid plate header is obviously unevenly distributed along the circumferential direction. To ameliorate this problem, prior art has typically placed porous baffles or orifice-like rectifying members inside the baffle headers and employed arrangements with symmetrical or uniform pore size, pore density, to attenuate the velocity gradient overall and reduce localized flow non-uniformities. However, such homogenizing arrangements are difficult to effectively inhibit local high momentum disturbances caused by the inlet jet, and also difficult to directionally compensate for the distal low momentum region, and often require an increase in overall throttling strength to achieve uniformity requirements, thereby leading to increased total pressure drop of the header, increased pumping power, and possibly inducing engineering risks such as local high-speed jet, scouring, vibration, and the like. Therefore, how to provide a porous baffle for improving the uniform outlet pressure of a grid plate header and a design method thereof are technical problems which are urgently needed to be solved by those skilled in the art. Disclosure of Invention In order to solve at least one technical problem in the background art, the invention provides a porous guide plate for improving the uniform outlet pressure of a grid plate header and a design method thereof, and aims at the strong disturbance characteristic of jet flow at the outlet of a main pipeline and drift flow of the inlet to a downstream pressure field on the premise of not obviously increasing the integral pressure drop of the grid plate header, and the influence of high-momentum jet flow and drift flow of the inlet on flow distribution in the header is weakened by introducing an inlet orifice plate at the inlet to pre-throttle and pre-equalize the fluid, so that the uniformity of the outlet pressure distribution of the grid plate header is improved, the accuracy and consistency of flow distribution of a fuel assembly are improved, and the component parameter simplification and the engineering processing assembly feasibility are considered. The invention provides a porous guide plate for improving uniform outlet pressure of a grid plate header, which comprises a cylindrical guide plate and an inlet small hole plate arranged on the inlet side of the cylindrical guide plate, wherein the cylindrical guide plate is arranged on the upper surface and the lower surface of the grid plate header through connecting pieces, liquid sodium coolant from a main pipeline is pretreated through the inlet small hole plate before entering the cylindrical guide plate, and a pre-pressure equalizing cavity is formed between the inlet small hole plate and the cylindrical guide plate and used for diffusing and homogenizing inlet jet flow so as to reduce disturbance of inlet drift flow to a downstream hole area. Further, the inlet orifice plate covers the inlet jet core area, and a plurality of inlet orifices are formed in the inlet orifice plate. Further, the inlet small holes are arranged in an array or a staggered array along the longitudinal and transverse directions, and the pitch of the holes is kept consistent. Further, the hole area of the cylindrical guide plate is not segmented circumfere