Design method of rectifier grid

Abstract

The design method for a rectifying grid disclosed in this invention belongs to the field of uneven airflow rectification and at least partially addresses the low rectification efficiency of existing grid designs. The airflow channel is divided into sections, and the local total pressure in each section is measured to create a total pressure distribution map. The blockage ratio of each section is calculated based on the total pressure distribution map. The size of the grid holes is then set based on the blockage ratio of each section, thereby improving the grid's rectification efficiency.

Description

Technical Field

[0001] The present invention belongs to the field of uneven airflow rectification, and in particular relates to a design method of a rectification grid. Background Art

[0002] In engineering, the uniformity of the airflow in the gas flow channel is a very important indicator, so the unevenness of the airflow is usually reduced by adding a rectifying grid (5) in the airflow channel. The traditional design method of the rectifying grid (5) is to make uniform circular holes or square holes with a certain blockage ratio on a flat plate of a certain thickness. When the uneven airflow (11) passes through the rectifying grid, the high-velocity part will move to the area with low velocity due to the blockage of the grid holes when passing through the grid holes, and pass through the grid holes from the low-velocity area, thereby achieving the purpose of rectifying the uneven airflow (11). However, the rectifying grid (5) designed by this traditional grid design method has a relatively large blockage, which will cause a large total pressure loss to the airflow. Summary of the Invention

[0003] In view of this, the present invention provides a design method for a rectifying grid, which at least partially solves the technical problem of low rectification efficiency of airflow in existing grid designs.

[0004] The present invention provides a method for designing a rectifier grid, the method comprising:

[0005] Divide the air flow channel into sections and measure the local total pressure in each section to create a total pressure distribution map;

[0006] Calculating the blockage ratio of each of the partitions according to the total pressure distribution map;

[0007] The size of the holes on the grille is set according to the blockage ratio of each partition area.

[0008] The technical beneficial effects of the present invention are:

[0009] According to the specific total pressure distribution map of the uneven airflow, the design result of the rectifier grid with refined design is obtained by calculation, which can greatly improve the rectification performance of the rectifier grid and reduce the total pressure loss of the rectifier grid; a larger local blockage ratio is set in the local high-speed area of the uneven airflow (11), and a smaller local blockage ratio is set in the local low-speed area of the uneven airflow (11), so that the efficient rectification of the uneven airflow (11) can be achieved under the condition of a smaller comprehensive blockage ratio. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0011] Figure 1 Schematic diagram of the flow field when uneven airflow is rectified through the rectifying grid;

[0012] Figure 2 Schematic diagram of flow field partitioning and local total pressure measurement;

[0013] Figure 3 An example of a refined rectifier grid design. DETAILED DESCRIPTION

[0014] The embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.

[0015] The following describes the embodiments of the present disclosure through specific examples, and those skilled in the art can easily understand other advantages and effects of the present disclosure from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all of the embodiments. The present disclosure can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present disclosure. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present disclosure.

[0016] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on this disclosure, it should be understood by those skilled in the art that an aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects described herein can be used to implement an apparatus and / or practice a method. In addition, other structures and / or functionalities other than one or more of the aspects described herein can be used to implement this apparatus and / or practice this method.

[0017] This case provides a design method for a rectifier grid, which includes:

[0018] S101: Divide the airflow channel into sections and measure the local total pressure of each section to create a total pressure distribution map. Specifically, the method for dividing the airflow channel into sections includes:

[0019] a1、 Figure 1 As shown, the diameter d of the designed flow channel, the flow design value M of the inlet section 1, and the total temperature T of the inlet airflow are obtained, and the flow process of the rectifying grid rectifying the uneven airflow 11 is divided into the inlet section 1, the total pressure test section 2, the grid front section 3, the rectifying grid 5, and the grid rear section 4. The pressure P3 of the grid front section 3 is the same as the pressure P2 of the total pressure test section 2. Preferably, the total pressure test section 2 is spaced 0.2d-0.5d from the inlet section 1, the distance between the rectifying grid and the inlet section 1 is 2d, and the distances between the grid front section 3 and the grid rear section 4 are 0.2d and 0.3d respectively.

[0020] a2. The total pressure distribution map is determined based on the airflow partitioning. The flow velocity of each sector annular surface of the grille front section 3 is calculated to determine the blockage ratio of each partition.

[0021] S102: Calculate the blockage ratio of each partition based on the total pressure distribution map. Specifically:

[0022] b1. Determine the overall parameters of the airflow channel and the uneven airflow to partition the airflow channel, and each partition is a sector annulus a, satisfying: a=A / N, A is the design cross-sectional area of the airflow channel, and N is the design number of the airflow channel. For example, the total pressure test section 2 is evenly divided into multiple sectors of equal area, and the number of sectors is 6-10; each sector is divided into multiple sector annuli 8 of equal area according to the equal annular surface distribution, and the number of sector annuli 8 in each sector is 4-8. Then, the total number of sector annuli in the airflow channel is N, and the area of each sector annulus a=A / N;

[0023] b2. Measure the local total pressure of each sector annular surface 8 in the total pressure test section, and calculate the local airflow parameters of each sector annular surface 8 in the front grille section 3. According to the principles of aerodynamics, the sector annular surfaces in the front grille section 3 are identical, and the airflow rate of each sector annular surface 8 is the total flow rate M divided by the number of sector annular surfaces 8 to obtain the flow rate m of each sector annular surface;

[0024] b3. Measure the pressure P of each partition of the total pressure test section 2 2-i-j , the pressure P of each partition of the front section 3 of the grid 3-i-j Equal to P 2-i-jThe uneven airflow at the inlet section 1 is blocked by the grille, causing the high-speed airflow to move toward the low-speed area and reach a nearly uniform state at the grille front section 3. The actual calculation assumes a uniform state. The local total temperature of the annular surface 8 of each sector at the grille front section 3 is the total temperature Tt of the inlet airflow at the inlet section 1. The local density ρ of the annular surface 8 of each sector at the grille front section 3 is the average density of the inlet airflow. The local total pressure P of each sector annular surface 8 is measured. t2-i-j : Arrange multiple total pressure test rakes 9 equal to the number of sectors in the total pressure test section 2. The circumferential position of the test rake is located at the center of each sector. The number of test points of each test rake is equal to the number of sector annulus 8. Each measuring point 10 is located at the center of the corresponding annulus to measure the local total pressure of each sector annulus 8. Obtain the total pressure distribution of the uneven airflow

[0025] b4. According to the local air flow function, we can get: qλ 3-i-j =m*T t 0.5 / 0.0404*P 3-i-j *a, and

[0026] Determine λ by looking up the one-dimensional isentropic flow aerodynamic function table 3-i-j The coefficient value of

[0027] b5. Calculate the local airflow velocity V of each partition in the front section 3 of the grille 3-i-j , and satisfy:

[0028] Calculate the local air velocity V 3-i-j =1.83* T t 0.5 *λ 3-i-j ;

[0029] b6. Measure the local total pressure of each sector annular surface 8 in the total pressure test section, and calculate the local airflow parameters of each sector annular surface 8 in the front grille section 3. According to the principles of aerodynamics, each sector annular surface in the front grille section 3 is identical. The airflow rate of each sector annular surface 8 is the total flow rate M divided by the number of sector annular surfaces 8 to obtain the flow rate m of each sector annular surface.

[0030] b7. The method for calculating the blockage ratio of each partition based on the total pressure distribution map includes:

[0031] Determine the target total pressure recovery coefficient σ of the design, and satisfy the following: target total pressure recovery coefficient = total pressure P of the grid rear section 4 t4 / Total pressure test section 2 total pressure P t2 , to determine the total pressure P in the section 4 behind the grid t4 The target total pressure recovery coefficient σ cannot be higher than the ratio of the local minimum total pressure of the total pressure test section 2 to the average total pressure Pt2 of the total pressure test section 2.

[0032] The blockage ratio of the rectifier grid 5 is determined to meet the following requirements:

[0033] , where: V 3-i-j is the local airflow velocity of the annular surface 8 of each sector of the front section 3 of the grid, Pt 3-i-j is the local total pressure of each partition, ρ is the local density of the annular surface 8 of each sector in the front section 3 of the grid; k is the total pressure loss coefficient of the rectifier grid 5. For the straight hole grid, the value of k is 1.3-1.6, and for the aerodynamic grid, the value of k is 1.9-2.3.

[0034] S103: The size of the holes on the grid is set according to the blockage ratio of each partition area, and the size of the annular hole of each grid sector is adjusted according to the blockage ratio of each partition of the rectifying grid 5.

[0035] Overall technology:

[0036] The total pressure distribution map of the uneven airflow in the flow channel is used to refine the design of the rectifier grille, so that the total pressure loss of the rectifier grille can be reduced while strengthening the rectifier grille's rectification ability. The main steps are: clarify the overall parameters of the airflow channel and the uneven airflow 11, such as the airflow channel area, the airflow channel radius, the total airflow flow M, the average total temperature Tt, etc., and then set the total pressure test section 2 after the inlet section 1, arrange several multi-point total pressure test rakes 9 in the section, and measure the local total pressure of the airflow in the pipeline in different zones, clarify the total pressure distribution map of the uneven airflow 11 in each zone of the flow channel, and then calculate the local blockage ratio of the grille corresponding to each zone through a series of steps, and finally form a grille design scheme 6. This design method realizes the refined design of the rectifier grille, sets a larger local blockage ratio in the local high-speed area of the uneven airflow 11, and sets a smaller local blockage ratio in the local low-speed area of the uneven airflow 11, which can achieve efficient rectification of the uneven airflow 11 under the condition of a smaller comprehensive blockage ratio. For specific uneven airflow total pressure distribution maps such as Figure 2 As shown in the figure, the refined rectifier grid design results are obtained by calculation, as shown in the figure. Figure 3 As shown, the rectification performance of the rectifier grid can be greatly improved while reducing the total pressure loss of the rectifier grid.

[0037] The above are only specific embodiments of the present disclosure, but the scope of protection of the present disclosure is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this disclosure should be included in the scope of protection of the present disclosure. Therefore, the scope of protection of the present disclosure should be based on the scope of protection of the claims.

Claims

1. A design method for a rectifier grid, characterized in that: The method comprises: Divide the air flow channel into sections and measure the local total pressure in each section to create a total pressure distribution map; The blockage ratio of each partition is calculated according to the total pressure distribution map, including determining the designed target total pressure recovery coefficient σ, and satisfying: σ = the total pressure P of the grid rear section (4) t4 / Total pressure P of total pressure test section (2) t2 , to determine the total pressure P in the section (4) behind the grid t4 , the blockage ratio of the rectifier grid (5) Certainty of satisfaction: , where: V 3-i-j is the local airflow velocity of the annular surface (8) of each sector of the front section (3) of the grille, Pt 3-i-j is the local total pressure of each partition, ρ is the local density of the annular surface (8) of each sector of the front section (3) of the grid; k is the total pressure loss coefficient of the rectifier grid (5), and for the straight hole grid, the value of k is 1.3-1.6, and for the aerodynamic grid, the value of k is 1.9-2.

3. The size of the annular hole of each grid sector is adjusted according to the blockage ratio of each partition of the rectifier grid (5); The size of the holes on the grille is set according to the blockage ratio of each partition.

2. The method according to claim 1, characterized in that The method for partitioning the air flow channel includes: Obtain the diameter d of the design airflow channel, the flow design value M of the inlet section (1), and the total temperature T of the inlet airflow t ; The flow process of the rectifier grid rectifying the uneven airflow (11) is divided into the inlet section (1), the total pressure test section (2), the grid front section (3), the rectifier grid (5) and the grid rear section (4). The pressure P of the grid front section (3) is t3 and the pressure P of the total pressure test section (2) t2 same.

3. The design method according to claim 2, characterized in that: The total pressure test section (2) is spaced 0.2d-0.5d from the inlet section (1), the rectifier grid is spaced 2d from the inlet section (1), and the grid front section (3) and grid rear section (4) are spaced 0.2d and 0.3d from the grid, respectively.

4. The design method according to claim 2, characterized in that: Also includes: Method for calculating the flow velocity of each sector annular surface of the front section of the grid (3): Determine the overall parameters of the airflow channel and the non-uniform airflow (11) to partition the airflow channel, and each partition is a sector annulus with an area a=A / N, where A is the design cross-sectional area of the airflow channel and N is the design number of the airflow channel; The local total pressure of each sector annulus (8) in the total pressure test section is measured, and the local parameters of the airflow of each sector annulus (8) in the front section of the grille (3) are calculated. According to the principle of aerodynamics, it can be known that the sector annuli of the front section of the grille (3) are the same, and the airflow rate of each sector annulus (8) is the total flow rate M divided by the number of sector annulus (8), and the flow rate of each sector annulus m can be obtained; Measure the pressure P of each partition of the total pressure test section (2) 2-i-j , the pressure P of each partition in the front section (3) of the grid 3-i-j Equal to P 2-i-j The total local temperature of the grille front section (3) and the annular surface (8) of each sector is the total temperature of the inlet airflow at the inlet section (1). t , the local density ρ of the annular surface (8) of each sector in the front section (3) of the grille is the average density of the inlet airflow; According to the local air flow function, q(λ 3-i-j ) = m*T t 0.5 / 0.0404*P 3-i-j *a, and determine λ by looking up the one-dimensional isentropic flow aerodynamic function table 3-i-j The coefficient value of Calculate the local airflow velocity V in each partition of the grille front section (3) 3-i-j , and satisfy: Calculate the local air velocity V 3-i-j =1.83* T t 0.5 *λ 3-i-j .

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