Device for inhibiting self-excited oscillation of grating-cavity flow field

Abstract

The utility model discloses a device for restraining self-excited oscillation of a grating-cavity flow field. The device for restraining the self-excited oscillation of the grating-cavity flow field comprises a box body (3), a grating (2) arranged at the top end of the box body and a restraining structure (1) arranged on the box body (3). According to the device for inhibiting the self-excited oscillation of the grid-cavity flow field, the self-excited oscillation phenomenon of the flow field is inhibited by utilizing the flow characteristic that fluid skims over the grid-cavity flow field inhibiting structure. The streamline appearance is adopted, so that the negative effects of flow resistance increase and the like caused by the existing oscillation suppression device can be reduced as much as possible. Meanwhile, the device is simple in structure and easy to machine and install, and the effects of prolonging the service life of related equipment with low cost can be achieved.

Description

Technical Field

[0001] The utility model relates to the field of grille plate structures, and particularly to a device for suppressing self-excited oscillation of a grille-cavity flow field. Background Technique

[0002] When fluid flows through a cavity with a grille, self-excited oscillation may occur. Self-excited oscillation refers to the oscillation of a system without external excitation. This kind of oscillation is usually related to factors such as the velocity of the fluid and the geometric shape of the structure. When the fluid flows through the grille area, it enters the cavity interior at the grille intervals in turn, and small-scale vortex clusters will be formed in the grille intervals. The small-scale vortex clusters break away from the grille intervals in turn, causing shear layer oscillation, which is also the source of positive disturbance at the grille separation edge (the front edge of the grille opening). When the fluid collides with the impact edge (the rear edge of the grille opening), reverse disturbance will also be generated. When the reverse disturbance propagates to the separation edge, it will amplify the positive disturbance, causing the small-scale vortex clusters to converge into large-scale vortex clusters, forming a pressure difference environment of high and low pressure at the grille. Thus, the self-excited oscillation effect of the grille-cavity flow field is formed.

[0003] Grille plates are usually used in fluid mechanics research, aerodynamics and engineering applications, such as wind tunnel experiments, air conditioning systems, building facades, automotive radiators, etc. Under some specific conditions, when fluid flows through the grille plate, oscillation may be triggered, which may lead to structural vibration and noise problems.

[0004] At present, there is no direct means to solve the self-excited oscillation of the cavity. Theoretically, methods such as changing the geometric shape of the grille plate or adding oscillation suppressors can be tried to solve this problem. However, these methods have certain limitations. First of all, such ideas usually require significant modifications to the grille plate, which may increase costs and complexity. Secondly, some methods are only effective under specific conditions, restricting their scope of application. In addition, some traditional methods may introduce additional friction or noise.

[0005] Therefore, it is necessary to provide an improved method to suppress the oscillation generated in the cavity when the fluid passes through by changing the structure in front of the grille, without fundamentally changing the entire grille plate. This method will overcome the limitations of the prior art, improve the overall stability and safety of the system when the fluid passes through, reduce costs and at the same time reduce maintenance requirements. Content of the Utility Model

[0006] The purpose of the utility model is to provide a device for suppressing self-excited oscillation of a grille-cavity flow field, which solves the problems mentioned in the background technique.

[0007] The present utility model is realized as follows. A device for suppressing self-excited oscillation of a grille-cavity flow field includes: a box body, a grille provided at the top end of the box body, and a suppression structure provided on the box body. The suppression structure is made of high-strength and lightweight materials and has a specific shape and size. It can be easily installed on the existing grille plate housing without large-scale modification. The shape of the suppression structure is carefully designed to reduce fluid resistance and improve the hydrodynamic performance of the plate. It is positioned at the front of the plate to stabilize fluid flow during high-speed operation and reduce oscillation problems at the grille and inside the cavity.

[0008] A further technical solution of the present utility model is that the suppression structure is provided on the box body and placed at the front end of the grille. Through the suppression structure for reducing self-excited oscillation at the grille-cavity, it is connected to the outer wall of the front end of the grille by inlaying or welding, and the suppression structure is located at the front end on one side of the cavity.

[0009] A further technical solution of the present utility model is that the suppression structure is in an arch shape. When the oncoming flow passes through the suppression structure, it will pass over the suppression structure, thus creating a difference from the original fluid flow state of the grille plate, that is, the fluid flows over the grille and the cavity, destroying the conditions for the formation of vortex clusters and avoiding excessive fluid entering the cavity to cause self-excited oscillation.

[0010] A further technical solution of the present utility model is that the suppression structure is connected to the box body. The self-excited oscillation phenomenon is only affected when the cavity length is very small. As the cavity height gradually increases, the self-excited oscillation of the flow field becomes easier to be excited. When the cavity size is large enough, the cavity wall will not affect the self-excited oscillation process.

[0011] The beneficial effects of the present utility model: The device for suppressing self-excited oscillation of the grille-cavity flow field of the present utility model utilizes the flow characteristics of the fluid passing over the suppression structure of the grille-cavity flow field to suppress the self-excited oscillation phenomenon of the flow field; adopts a streamlined shape to minimize the negative impacts such as the increase in flow resistance caused by the existing oscillation suppression device; at the same time, the device has a simple structure, is easy to process and install, and can achieve the effect of extending the service life of related equipment with less cost. Description of the Drawings

[0012] Figure 1 is a sectional view of a device for suppressing self-excited oscillation of a grille-cavity flow field provided by the present utility model;

[0013] Figure 2 is a graph of the pressure coefficient at the impact edge of the grille before adding the suppression structure for a device for suppressing self-excited oscillation of a grille-cavity flow field provided by the present utility model;

[0014] Figure 3It is the diagram of the pressure coefficient at the impact edge of the grid after adding a suppression structure for a device provided by the present utility model to suppress the self-excited oscillation of the grid-cavity flow field;

[0015] Figure 4 It is the spectrum diagram of the grid impact edge before adding a suppression structure for a device provided by the present utility model to suppress the self-excited oscillation of the grid-cavity flow field;

[0016] Figure 5 It is the spectrum diagram of the grid impact edge after adding a suppression structure for a device provided by the present utility model to suppress the self-excited oscillation of the grid-cavity flow field;

[0017] Figure 6 It is the schematic diagram of the overall structure of a device provided by the present utility model to suppress the self-excited oscillation of the grid-cavity flow field. Specific embodiments

[0018] The following illustrates the embodiments of the present utility model through specific examples. Those skilled in the art can easily understand the other advantages and effects of the present utility model from the content disclosed in this specification. The present utility model can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present utility model.

[0019] It should be noted that the structures, ratios, sizes, etc. shown in the drawings of this specification are only used to cooperate with the content disclosed in the specification for those skilled in this technology to understand and read, and are not used to limit the limiting conditions under which the present utility model can be implemented. Therefore, they do not have a technical essence. Any modification of the structure, change of the proportional relationship, or adjustment of the size, without affecting the effects that the present utility model can produce and the purposes that can be achieved, should still fall within the scope that can be covered by the technical content disclosed in the present utility model. At the same time, the terms such as "upper", "lower", "left", "right", "middle", and "one" cited in this specification are only for the convenience of clear description and are not used to limit the scope under which the present utility model can be implemented. The change or adjustment of their relative relationships, without substantial change in the technical content, should also be regarded as the scope within which the present utility model can be implemented.

[0020] Example 1: Figure 1A device for suppressing self-excited oscillation of a grille-cavity flow field is shown. The device for suppressing self-excited oscillation of the grille-cavity flow field includes: a box body 3, a grille 2 arranged at the top end of the box body, and a suppression structure 1 arranged on the box body 3. The suppression structure is made of high-strength and lightweight materials and has a specific shape and size. It can be easily installed on the existing grille plate housing without large-scale modification. The shape of the suppression structure is carefully designed to reduce fluid resistance and improve the hydrodynamic performance of the plate. It is positioned at the front of the plate to stabilize fluid flow during high-speed operation, reduce oscillation problems at the grille and inside the cavity; the suppression structure 1 is arranged on the box body 3 and placed at the front end of the grille 2. Through the suppression structure for reducing self-excited oscillation at the grille-cavity, it is connected to the outer wall of the front end of the grille by inlaying or welding, and the suppression structure is located at the front end on one side of the cavity; the suppression structure 1 is in an arch shape. When the oncoming flow passes through the suppression structure, it will pass over the suppression structure, thus creating a difference from the original fluid flow state of the grille plate, that is, the fluid flows over the grille and the cavity, destroying the conditions for the formation of vortex clusters and preventing too much fluid from entering the cavity to cause self-excited oscillation; the suppression structure 1 is connected to the box body 3. The self-excited oscillation phenomenon is only affected when the cavity length is very small. As the cavity height gradually increases, the self-excited oscillation of the flow field becomes easier to be excited. When the cavity size is large enough, the cavity wall will not affect the self-excited oscillation process; the device for suppressing self-excited oscillation of the grille-cavity flow field of the present invention utilizes the flow characteristics of the fluid passing over the suppression structure of the grille-cavity flow field to suppress the self-excited oscillation phenomenon of the flow field. Adopting a streamlined shape can minimize the negative impacts such as the increase in flow resistance caused by existing oscillation suppression devices. At the same time, the device has a simple structure, is easy to process and install, and can achieve the effect of extending the service life of related equipment with less cost.

[0021] The shape of the suppression structure is carefully designed to reduce fluid resistance and improve the hydrodynamic performance of the plate: First, according to the sensitivity analysis method, determine the parameters that have a relatively large impact on the oscillation amplitude in the cavity, and then perform parametric modeling: the suppression structure-grille-cavity and the original grille-cavity model, select multiple parameters for optimization simulation, determine the range of optimal parameters, then extract its geometric parameters for modeling, and then reasonably extract the fluid domain for mesh generation, and then import it into the numerical simulation software for solution. Considering that the simulation should be as close to reality as possible, the k-w-GEKO model is selected for solution. After a sufficiently long steady-state solution, a transient solution is carried out. Since the influence of different wind speeds on the experiment needs to be considered, different wind speed gears are selected during the solution process to determine the influence of different factors on the calculation. Before starting the calculation, set each calculation convergence criterion to 1×10 -6, to ensure that the calculation can reach the convergence state as much as possible. Then monitor the required physical quantities. The monitoring point is located at the place where air enters the cavity, and the pressure coefficient is monitored. Start the calculation. When the degree of convergence drops to a certain level and remains stable, and the monitored parameters hardly change anymore, the calculation ends and the convergence state is reached.

[0022] If the calculation results show that there are intense self-excited oscillations in the original grille-cavity model, and the oscillation of the optimized suppression structure-grille-cavity model is significantly suppressed compared with the original model, and if the error is within the acceptable range, it proves that the optimization method of this invention is feasible.

[0023] The initial case is simulated according to the original parameters without a suppression structure in front of the grille, and the wind speed is uniformly set to 30 m / s.

[0024] For the optimized case, a suppression structure is added and the wind speed remains unchanged.

[0025] The monitoring points and monitored parameters of the two cases are the same; the monitoring points of the calculation example are evenly distributed in the middle of the grille. Since the eddy current is obvious and the oscillation is intense at the impact edge, the monitoring point at the impact edge of the grille end is taken to compare the results. After optimization, the pressure is significantly suppressed and the cavity oscillation weakens.

[0026] The above are only the preferred embodiments of the present utility model and are not intended to limit the present utility model. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present utility model shall be included within the protection scope of the present utility model.

Claims

1. A device for suppressing self-excited oscillation of a grid-cavity flow field, characterized in that: The device for suppressing self-excited oscillation of a grid-cavity flow field comprises: a box body (3), a grid body (2) arranged at the top end of the box body, and a suppression structure (1) arranged on the box body (3).

2. The device for suppressing self-oscillation of grid-cavity flow field according to claim 1, characterized in that: The suppression structure (1) is arranged on the box body (3) and is placed at the front end of the grille (2).

3. The device for suppressing self-oscillation of grid-cavity flow field according to claim 1, characterized in that: The restraining structure (1) is arch-shaped.

4. The device for suppressing self-oscillation of grid-cavity flow field according to claim 1, characterized in that: The restraining structure (1) is connected to the housing (3).

Images