Optimization method for flow area of noise elimination air duct of range hood and range hood

Abstract

The invention relates to the technical field of range hoods, in particular to an optimization method for the flow area of a noise elimination air duct of a range hood and the range hood, and at least solves the problem of how to optimize the flow area of the air duct. The optimization method comprises the following steps: respectively acquiring impedance of the smoke collection component, the noise elimination air duct and the public flue, calculating total impedance, and calculating a ratio of the impedance of the noise elimination air duct to the total impedance; the specific value is compared with a preset proportion threshold value, and the circulation area of the silencing air duct is selectively and preliminarily adjusted; based on the current flow area, selecting a preset optimized flow area, and respectively calculating an acoustic power level change value and an acoustic transmission loss change value after the flow area is optimized; and comparing the current flow area with the optimized flow area, comparing the sound power level change value with the sound transmission loss change value, and determining the target flow area of the silencing air duct based on the comparison result and the selected preset optimized flow area. The optimization scheme of the flow area of the silencing air duct can be obtained.

Description

Technical Field

[0001] The invention relates to the technical field of range hoods, and specifically provides a method for optimizing the flow area of ​​a silencer air duct of a range hood and a range hood. Background Art

[0002] Noise has become a major problem in the use of range hoods, and the noise reduction technology currently widely used has approached its upper limit, making it difficult to effectively reduce the noise level of range hoods. In addition, there is a clear gap between the noise data measured in a standard semi-anechoic room and the actual experience of users in real application scenarios, which has prompted users to pay more attention to the noise conditions of range hoods in actual operation.

[0003] In order to accurately evaluate the noise performance of the range hood in actual operation, the matching degree and synergy between the range hood and the entire fume exhaust system must be fully considered. In the fume exhaust system, the flow area of ​​the air duct is a key factor, which directly affects the exhaust efficiency and noise level of the range hood. Therefore, how to reasonably set the flow area of ​​the air duct has become an urgent problem to be solved. Summary of the invention

[0004] The present invention aims to solve the above technical problem, that is, at least to solve the problem of how to optimize the flow area of ​​the air duct.

[0005] In a first aspect, the present invention provides a method for optimizing the flow area of ​​a muffler air duct of a range hood, wherein the range hood comprises a smoke collecting component, a muffler air duct and a main box connected in sequence to thereby construct a smoke channel, and the smoke channel is connected to a common smoke channel to thereby construct a smoke exhaust channel, and the optimization method comprises:

[0006] S1. respectively obtaining the impedance of the smoke collecting component, the impedance of the muffler air duct and the impedance of the common flue, calculating the total impedance, and calculating the ratio of the impedance of the muffler air duct to the total impedance;

[0007] S2, comparing the ratio with a preset ratio threshold, and selectively and preliminarily adjusting the flow area of ​​the muffler air duct according to the comparison result to obtain a current flow area;

[0008] S3. Based on the current flow area, a preset optimized flow area is selected, and a change value of the sound power level and a change value of the sound transmission loss after the flow area is optimized are calculated respectively;

[0009] S4. Compare the current flow area with the selected preset optimized flow area, compare the sound power level change value with the sound transmission loss change value, and determine the target flow area of ​​the silencer duct based on the comparison result and the selected preset optimized flow area.

[0010] The present invention can preliminarily adjust the flow area of ​​the silencer air duct by limiting the proportion of the impedance of the silencer air duct in the total impedance of the smoke exhaust channel so that it does not exceed a preset proportion threshold. The result of this preliminary adjustment provides a data basis for subsequent optimization and adjustment, greatly reducing the error range.

[0011] On this basis, a preset optimized flow area is further selected as a reference, and the change values ​​of sound power level and sound transmission loss after the flow area is optimized are calculated. The changes in these two indicators provide an important basis for measuring the optimization effect. By comparing the change values ​​of sound power level and sound transmission loss, the actual effect of the optimization can be more intuitively understood, and the flow area of ​​the silencer air duct can be adjusted more finely accordingly. After such an optimization process, an optimal flow area of ​​the silencer air duct can be finally determined.

[0012] The design of the muffler air duct with this flow area can not only significantly reduce the noise level of the range hood with a slight increase in system resistance, but also ensure that the exhaust efficiency of the range hood is not affected. In other words, this optimization solution can effectively reduce the operating noise of the range hood while maintaining its efficient operation, providing users with a more comfortable experience.

[0013] In some feasible implementations of the above-mentioned optimization method, the “selectively and preliminarily adjusting the flow area of ​​the muffler air duct to obtain the current flow area according to the comparison result” includes:

[0014] S21, if the ratio is greater than or equal to the preset ratio threshold, increase the flow area of ​​the muffler air duct, and return to step S1; or

[0015] S22. If the ratio is less than, equal to or less than the preset ratio threshold, the flow area of ​​the silencer air duct is not adjusted, and the current flow area is obtained.

[0016] It can be understood that when the ratio is greater than or equal to the preset ratio threshold, it means that the impedance of the silencer air duct accounts for too high a proportion of the total impedance of the smoke exhaust channel, which may cause louder noise or reduced smoke exhaust efficiency when the range hood is running. At this time, by increasing the flow area of ​​the silencer air duct, its impedance can be reduced, thereby improving the performance of the range hood.

[0017] And the adjusted flow area needs to be recalculated and the ratio compared to ensure that the impedance of the adjusted silencer air duct meets the requirements. This dynamic adjustment and feedback mechanism ensures the accuracy and effectiveness of the optimization process. If the ratio is less than or equal to or less than the preset ratio threshold, it means that the impedance of the silencer air duct is within a reasonable range. At this time, there is no need to further adjust the flow area, and the next step of optimization can be directly entered.

[0018] In some feasible implementations of the above-mentioned optimization method, the “determining the target flow area of ​​the muffler air duct based on the comparison result and the selected preset optimized flow area” includes:

[0019] S41. If the preset optimized flow area is smaller than the current flow area, and the increase in the sound power level is smaller than or equal to the increase in the sound transmission loss, the preset optimized flow area is determined as the target flow area of ​​the muffler duct; or

[0020] S42, if the preset optimized flow area is smaller than the current flow area, and the increase in the sound power level is greater than, equal to, or greater than the increase in the sound transmission loss, the preset optimized flow area is determined as the current flow area, and the process returns to step S3; or

[0021] S43, if the preset optimized flow area is larger than the current flow area, and the reduction value of the sound power level is larger than or equal to the reduction value of the sound transmission loss, then the preset optimized flow area is determined as the target flow area of ​​the muffler air duct; or

[0022] S44. If the preset optimized flow area is larger than the current flow area, and the reduction value of the sound power level is less than, equal to, or less than the reduction value of the sound transmission loss, the preset optimized flow area is determined as the current flow area, and the process returns to step S3.

[0023] It is understandable that if the preset optimized flow area is smaller than the current flow area, it means that the noise reduction air duct is planned to be optimized by reducing the flow area. At this time, by comparing the increase in the sound power level with the increase in the sound transmission loss, it can be evaluated whether the noise level of the range hood will increase or decrease after reducing the flow area. Specifically:

[0024] When the sound power level change value is less than or equal to the sound transmission loss change value, it means that although the sound energy (sound power level) emitted by the sound source has increased, the attenuation of the sound during propagation (sound transmission loss) has also increased accordingly, and this attenuation increase is sufficient to offset the increase in sound source energy, and even makes the noise level that finally reaches the receiving point lower than before optimization. Therefore, in this case, it can be determined that the preset optimized flow area meets the optimization conditions and can be determined as the target flow area of ​​the silencer duct.

[0025] On the contrary, if the change in sound power level is equal to or greater than the change in sound transmission loss, the increase in sound source energy will exceed the attenuation of sound during propagation, resulting in an increase in the noise level of the range hood when it is working compared to before optimization. At this time, the preset optimized flow area does not meet the optimization conditions, so the preset optimized flow area should be used as the new current flow area and the next round of optimization attempts should be repeated. Through the above process, the flow area of ​​the silencer air duct can be accurately adjusted to achieve the best balance between reducing noise and maintaining range hood performance.

[0026] Similarly, if the preset optimized flow area is larger than the current flow area, it means that the noise reduction duct is planned to be optimized by expanding the flow area. In this optimization process, by comparing the reduction in sound power level with the reduction in sound transmission loss, it is evaluated whether the noise level of the range hood increases or decreases after the flow area is expanded. Specifically:

[0027] When the reduction value of the sound power level is greater than or equal to the reduction value of the sound transmission loss, it means that the sound energy (sound power level) generated by the sound source is reduced, and the attenuation of the sound during propagation (i.e., the sound transmission loss) is also reduced accordingly, but the reduction in attenuation does not exceed the reduction in the sound power level, so the noise level that finally reaches the receiving point is reduced. In this case, the preset optimized flow area meets the optimization conditions and can be determined as the target flow area of ​​the muffler duct.

[0028] On the contrary, if the reduction in sound power level is less than, equal to, or less than the reduction in sound transmission loss, the noise generated by the optimized range hood during operation may increase compared to before optimization. This is because the attenuation of sound during propagation is reduced more, resulting in an increase in the noise level that finally reaches the receiving point. In this case, the preset optimized flow area does not meet the optimization conditions because it causes an increase in the noise level. Therefore, the preset optimized flow area should be used as the new current flow area and the next round of optimization attempts should be repeated. Through the above process, the flow area of ​​the silencer air duct can be accurately adjusted to achieve the best balance between reducing noise and maintaining range hood performance.

[0029] In some feasible implementations of the above-mentioned optimization method, the process of obtaining the impedance of the silencer air duct is: constructing a simulated air duct and establishing a simulation model of the simulated air duct; conducting a simulation experiment based on the simulation model of the simulated air duct, and calculating the impedance of the silencer air duct by analyzing the simulation results.

[0030] In some feasible implementations of the above-mentioned optimization method, the simulated air duct includes a main pipe and an extension pipe that are interconnected; there are two extension pipes, which are respectively arranged at two ends of the main pipe; wherein the cross-section of the section of the extension pipe close to the main pipe is arranged to be a structure that gradually tapers outward from the main pipe.

[0031] It can be understood that the two extended pipes are defined as a gradually expanding pipe and a gradually converging pipe respectively. Since there is generally a certain gradual contraction process or gradual expansion process when the silencer air duct and the smoke collecting component or the main box are connected, in order to ensure the accuracy of the simulation results, the resistance of the gradually converging pipe or the gradually expanding pipe is attributed to the simulated air duct during simulation. This means that in the simulation process, the influence of these connecting parts on the airflow resistance is taken into account, making the simulation results closer to the actual situation, thereby improving the accuracy of the simulation results.

[0032] In some feasible implementations of the above-mentioned optimization method, the "conducting a simulation experiment based on the simulation model of the simulated air duct, and calculating the impedance of the silencer air duct by analyzing the simulation results" includes: in the simulation model of the simulated air duct, selecting a preset number of working conditions, and reading the outlet pressure of each working condition; based on the outlet pressure of each working condition, calculating the resistance coefficient of the simulated air duct in each working condition, and fitting the relationship model between the flow area and the resistance coefficient of the simulated air duct; based on the relationship model between the flow area and the resistance coefficient of the simulated air duct, calculating the impedance of the simulated air duct in each working condition, and establishing a relationship model between the flow area and the impedance of the simulated air duct; inputting the flow area of ​​the silencer air duct into the relationship model between the flow area and the impedance of the simulated air duct to obtain the impedance of the silencer air duct.

[0033] In some feasible implementations of the above optimization method, the “calculating the resistance coefficient of the simulated air duct in each working condition based on the outlet pressure of each working condition” is calculated by formula (1):

[0034]

[0035] Wherein, ΔP is the pressure loss value of the simulated air duct, ξ is the resistance coefficient of the simulated air duct, ρ is the air density, and v is the average wind speed of the simulated air duct; and / or

[0036] The “calculating the impedance of the simulated air duct in each working condition based on the relationship model between the flow area and the resistance coefficient of the simulated air duct” is calculated by formula (2):

[0037]

[0038] Among them, S is the impedance of the simulated air duct, ξ is the resistance coefficient of the simulated air duct, ρ is the air density, and A is the cross-sectional area of ​​the simulated pipe.

[0039] In some feasible implementations of the above-mentioned optimization method, a fan is provided in the main box, and the process of obtaining the change value of the sound power level after the flow area is optimized includes: based on the current flow area and the preset optimized flow area, respectively calculating the total impedance of the range hood before optimization and the total impedance after optimization, and constructing different characteristic curves of the fan under the corresponding total impedance; under the condition of rated working air volume, calculating the speed of the fan before optimization and the speed after optimization according to the characteristic curve of the fan; based on the speed of the fan before optimization and the speed after optimization, calculating the change value of the sound power level after optimization.

[0040] In some feasible implementations of the above-mentioned optimization method, the process of obtaining the change value of the sound transmission loss after the flow area is optimized includes: calculating the current cross-sectional area of ​​the sound absorbing material based on the current flow area; calculating the preset optimized cross-sectional area of ​​the sound absorbing material based on the preset optimized flow area; establishing a noise loss simulation model, inputting the current cross-sectional area of ​​the sound absorbing material and the preset optimized cross-sectional area of ​​the sound absorbing material into the noise loss simulation model respectively, and obtaining the optimized sound transmission loss change value through comparison.

[0041] In a second aspect, the present invention further provides a range hood, comprising a silencer air duct, wherein the silencer air duct is designed by the flow area optimization method of the range hood silencer air duct in any of the aforementioned technical solutions.

[0042] Those skilled in the art can understand that, since the silencer air duct of the range hood is designed by the optimization method of the flow area of ​​the silencer air duct of the range hood in any of the aforementioned technical solutions, the range hood has all the technical effects that can be obtained by the aforementioned optimization method, which will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings, in which:

[0044] Figure 1 A flowchart of a method for optimizing the flow area of ​​a range hood silencer air duct provided in Embodiment 1 of the present invention;

[0045] Figure 2 A schematic diagram of the structure of the smoke exhaust channel provided in Example 1 of the present invention;

[0046] Figure 3 A schematic diagram of the structure of the simulated air duct provided in Example 1 of the present invention;

[0047] Figure 4 A schematic diagram of the structure of the smoke collecting component provided in Example 1 of the present invention during simulation;

[0048] Figure 5A fitted linear graph of the resistance coefficient-flow area of ​​the simulated air duct provided in Example 1 of the present invention;

[0049] Figure 6 A schematic diagram of a curve showing the relationship between impedance and flow area of ​​a simulated air duct provided in Example 1 of the present invention;

[0050] Figure 7 A schematic diagram of the wind pressure-air volume characteristic curve of the fan provided in Example 1 of the present invention at different speeds and different total impedances.

[0051] Reference numerals:

[0052] 100, smoke collecting component; 200, silencer air duct; 210, main duct; 220, expansion duct; 221, gradually expanding pipe; 222, gradually converging pipe; 300, main box; 310, fan; 400, public flue. DETAILED DESCRIPTION

[0053] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not used to limit the scope of protection of the present invention. Those skilled in the art can make adjustments as needed to adapt to specific applications. In order to better illustrate the present invention, numerous specific details are given in the specific embodiments below. It should be understood by those skilled in the art that the present invention can also be implemented without certain specific details.

[0054] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installation" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0055] See also Figure 2 The embodiment of the present invention provides a range hood, which includes a smoke collecting component 100, a muffler air duct 200 and a main box 300 connected in sequence, wherein a fan 310 is arranged in the main box 300, and the three are internally connected to form a smoke channel, and the smoke channel is connected to the public flue 400 to form a smoke exhaust channel. That is, the smoke collecting component 100, the muffler air duct 200 and the volute of the fan 310 in the main box 300 form a smoke channel, and the smoke channel is a channel inside the range hood, and the smoke channel and the public flue 400 form a smoke exhaust channel. Under the driving action of the fan 310, the smoke is sucked into the smoke channel, and then discharged to the outside along the public flue 400.

[0056] Among them, the flow area of ​​the silencer air duct 200 is a key parameter, which directly affects the smoke exhaust efficiency and noise level of the range hood. How to reasonably set the flow area of ​​the silencer air duct 200 so that the range hood generates less noise while ensuring the smoke exhaust efficiency. The present invention provides a method for optimizing the flow area of ​​the silencer air duct 200 of the range hood. The silencer air duct 200 designed by this method can ensure the smoke exhaust efficiency while keeping the range hood at a lower noise level.

[0057] Specifically, see Figure 1 The method for optimizing the flow area of ​​the range hood silencer air duct 200 provided by the present invention includes:

[0058] S1, respectively obtain the impedance S1 of the smoke collecting component 100, the impedance S2 of the muffler air duct 200 and the impedance S3 of the common flue 400, calculate the total impedance S4, and calculate the ratio of the impedance S2 of the muffler air duct 200 to the total impedance S4.

[0059] Specifically, when the size of the range hood is limited, the flow area of ​​the silencer duct 200 is not only directly related to the exhaust efficiency of the range hood, but also has a significant regulating effect on its noise level. In order to find a flow area that can effectively exhaust air without causing excessive noise, it is necessary to conduct in-depth research on the key impact of the flow area on the performance of the range hood. Since the change in flow area is often accompanied by a corresponding change in impedance, an effective entry point is to study the ratio between the impedance of the silencer duct 200 and the total impedance. This ratio can provide a perspective: how the change in flow area causes a corresponding change in impedance, and how it affects the performance of the range hood. During the study, in order to reduce the ratio of the impedance of the silencer duct 200 to the total impedance, it is necessary to adjust the flow area of ​​the silencer duct 200, which can be achieved by optimizing the shape, size and material of the silencer duct 200.

[0060] Within the scope of reasonable adjustment of the circulation area, the increase in the circulation area of ​​the silencer air duct 200 will usually improve its smoke exhaust efficiency. This is because a larger circulation area can reduce the obstruction of the airflow in the air duct, allowing the airflow to pass more smoothly, thereby improving the smoke exhaust efficiency. At the same time, as the circulation area of ​​the silencer air duct 200 increases, its impedance will decrease accordingly, and then the ratio of the impedance of the silencer air duct 200 to the total impedance will also decrease. This means that the obstacles encountered by the sound when passing through the silencer air duct 200 are reduced, reducing the reflection and enhancement of the sound, which helps to reduce the overall noise level of the range hood.

[0061] It should be noted that the main box 300 provided with the fan 310 is the power component of the range hood, and the others are resistance components. Since the impedance of the series pipes is equal to the sum of the impedances of each pipe, the total impedance S4 = S1 + S2 + S3. Among them, the impedance S2 of the muffler air duct 200 is obtained based on the initial design flow area of ​​the muffler air duct 200, and the initial design flow area is the flow area without any adjustment.

[0062] Specifically, the impedance of the muffler air duct 200 is obtained as follows:

[0063] S11. Construct a simulated air duct and establish a simulation model of the simulated air duct.

[0064] See also Figure 3 The simulated air duct is a simulated muffler air duct 200, which includes a main duct 210 and an extension duct 220 that are interconnected. There are two extension ducts 220, which are respectively arranged at two ends of the main duct 210. The cross section of the extension duct 220 close to the main duct 210 is set to a structure that tapers outward from the main duct 210.

[0065] Among them, the two expansion pipes 220 are defined as the gradually expanding pipe 221 and the gradually contracting pipe 222 respectively. Since there is generally a certain gradual expansion process (or gradual contraction process) when the silencer air duct 200 and the smoke collecting component 100 (or the main box 300 are connected), in order to ensure the accuracy of the simulation results, the resistance of the gradually contracting pipe 222 or the gradually expanding pipe 221 is attributed to the simulated air duct during the simulation, which means that during the simulation process, the influence of these connecting parts on the airflow resistance is taken into account, so that the simulation results are closer to the actual situation, thereby improving the accuracy of the simulation results. Among them, during the simulation, the main pipe 210 is a rectangular structure, and the cross-sectional area of ​​the expansion pipe 220 is equal to the smallest flow area in the main pipe 210.

[0066] S12, based on the simulation model of the simulated air duct, a simulation experiment is performed, and the impedance of the muffler air duct 200 is calculated by analyzing the simulation results. Specifically, step S12 specifically includes:

[0067] S121. In the simulation model of the simulated air duct, a preset number of working conditions are selected, and the outlet pressure of each working condition is read.

[0068] It should be noted that the specific working condition parameters and quantities are set according to the actual situation. For example, in one implementation scenario, three working conditions of the cross-sectional area of ​​the muffler air duct 200 can be set, which are 0.02948m 3 、0.04020m 3 、0.05092m 3The corresponding length and width are 220mm×134mm, 300mm×134mm, and 380mm×134mm. The boundary conditions are: the inlet pressure is 0Pa, the outlet velocity is 5m / s, and 5 layers of refined boundary layer grids are set on the wall. The k-omega SST model (i.e., shear stress transfer model) is selected as the turbulence model. The outlet pressure of each working condition is read by simulation.

[0069] S122. Based on the outlet pressure of each working condition, the resistance coefficient of the simulated air duct in each working condition is calculated, and a relationship model between the flow area and the resistance coefficient of the simulated air duct is fitted.

[0070] See also Figure 5 , Figure 5 It is the fitted linear diagram of the resistance coefficient-flow area of ​​the simulated air duct. Figure 5 The linear fitting function of the flow area and resistance coefficient of the simulated air duct can be obtained. Within a certain flow area range, the resistance coefficient has a small difference. Specifically, based on the inlet pressure and outlet pressure of each working condition, the pressure loss value ΔP of the simulated air duct can be calculated, and the resistance coefficient of the simulated air duct in each working condition is calculated by formula (1):

[0071]

[0072] Among them, ΔP is the pressure loss value of the simulated air duct, the unit is Pa; ξ is the resistance coefficient of the simulated air duct; ρ is the air density, usually ρ = 1.2kg / m 3 ; v is the average wind speed in the simulated wind duct, in m / s.

[0073] S123. Based on the relationship model between the flow area and the resistance coefficient of the simulated air duct, the impedance of the simulated air duct in each working condition is calculated, and a relationship model between the flow area and the impedance of the simulated air duct is established.

[0074] See also Figure 6 , Figure 6 This is a schematic diagram of the impedance-flow area relationship curve for simulating the air duct. When the flow area is small, the impedance increases sharply. For the convenience of comparison and reference, you can also Figure 6 The relationship curve between the proportion of the impedance of the simulated air duct in the total impedance and the flow area is added. Specifically, based on the relationship model between the flow area and the resistance coefficient of the simulated air duct, the impedance of the simulated air duct in each working condition is calculated by formula (2):

[0075]

[0076] Where S is the impedance of the simulated wind duct; ξ is the resistance coefficient of the simulated wind duct; ρ is the air density, usually ρ = 1.2 kg / m 3; A is the cross-sectional area of ​​the simulated air duct on the reference section, in m 2 .

[0077] It should be noted that formula (2) is derived from formula (1), formula (3) and formula (4):

[0078] ΔP=SQ 2 Formula (3)

[0079] Among them, ΔP is the pressure loss value of the simulated air duct, the unit is Pa; S is the impedance of the simulated air duct; Q is the pipe flow rate of the simulated air duct, the unit is m 3 / min.

[0080]

[0081] Among them, v is the average wind speed of the simulated air duct, in m / s; Q is the pipe flow rate of the simulated air duct, in m 3 / min; A is the cross-sectional area of ​​the simulated air duct on the reference section, in m 2 .

[0082] S124 , inputting the flow area of ​​the silencer air duct 200 into a relationship model between the flow area and impedance of the simulated air duct to obtain the impedance of the silencer air duct 200 .

[0083] Specifically, before inputting data, the model can be verified using a known data set of flow area and impedance to ensure the accuracy and reliability of the model. After successful verification, the flow area of ​​the muffler air duct 200 is input to obtain the corresponding impedance of the muffler air duct 200.

[0084] In addition, the method for obtaining the impedance of the smoke collecting component 100 is similar to the method for obtaining the impedance of the muffler air duct 200 in key links such as modeling and formula calculation. The method for obtaining the impedance of the smoke collecting component 100 is specifically as follows:

[0085] Since the shape and size of the smoke collecting component 100 are determined, its impedance S1 can be directly calculated by CFD (computational fluid dynamics) simulation. The fluid domain of the simulation model is as follows: Figure 4 As shown, certain extension pipe sections are set at the inlet and outlet of the smoke collecting component 100 to ensure the stability of the simulation calculation. However, since the extension pipe section is short and mainly causes resistance loss along the way, the influence of this part is ignored in the calculation. The boundary conditions are: the inlet pressure is 0Pa, the outlet velocity is 5m / s, and 5 layers of refined boundary layer grids are set on the wall. The k-omegaSST model (i.e., shear stress transmission model) is selected as the turbulence model. The outlet pressure of the smoke collecting component 100 is simulated and read, and then the impedance S1 of the smoking port is calculated using formulas (1) and (2).

[0086] In one embodiment, according to CFD simulation calculation, the impedance of the smoking port S1 = 0.1; the average impedance of the public flue 400 of the user can be S3 = 2.1; therefore, the total impedance S4 = 2.2 + S2, when the impedance S2 of the silencer duct 200 is small, that is, S2 is a minimum value compared to the value 2.2, the ratio of the impedance S2 of the silencer duct 200 to the total impedance S4 is also relatively small.

[0087] It should be noted that, in some cases, the minimum impedance is not the optimal solution for the range hood. For example, sacrificing some flow area of ​​the silencer air duct 200 can effectively reflect the noise to form a sound shadow area to reduce the operating noise of the range hood. However, the resistance increases and a certain speed needs to be increased to achieve the original air volume. The increase in speed increases the noise of the sound source. However, if the effect of the reflected noise is greater than the effect of the increased sound source, then the optimization is meaningful.

[0088] S2. Compare the ratio with a preset ratio threshold, and selectively and preliminarily adjust the flow area of ​​the muffler air duct 200 according to the comparison result to obtain the current flow area.

[0089] Specifically, from the perspective of fluid mechanics, there is an inverse relationship between flow velocity and flow area. That is, when the flow area increases, the flow velocity will decrease accordingly. This may cause the pressure loss of the fluid in the system to decrease, but it may also cause the friction and vibration of the fluid in the pipeline to increase, thereby generating greater noise. Therefore, a balance needs to be found between pursuing smoke exhaust efficiency and reducing noise. In order to determine this balance point, the embodiment of the present invention sets a preset proportional threshold as a reference benchmark. The preset proportional threshold needs to be accurately determined through multiple experimental tests. It represents the ratio of the impedance S2 of the silencer air duct 200 to the total impedance S4. The silencer air duct 200 corresponding to this ratio can ensure that while improving the smoke exhaust efficiency, it can also effectively suppress noise, so that the performance of the range hood is in a better state. In one embodiment, the preset proportional threshold can be 5%.

[0090] It should be noted that the numerical values ​​in the above examples are merely exemplary and should not be construed as limiting the scope of protection of the present invention.

[0091] After comparing the ratio with the preset ratio threshold, the step of selectively and preliminarily adjusting the flow area of ​​the muffler air duct 200 to obtain the current flow area according to the comparison result specifically includes:

[0092] S21. If the ratio is greater than or equal to a preset ratio threshold, the flow area of ​​the muffler air duct 200 is increased, and the process returns to step S1.

[0093] It can be understood that when the ratio is greater than or equal to the preset ratio threshold, it means that the impedance of the silencer duct 200 accounts for too high a proportion of the total impedance of the smoke exhaust channel, which may cause louder noise or reduced smoke exhaust efficiency when the range hood is running. At this time, by increasing the flow area of ​​the silencer duct 200, its impedance can be reduced, thereby improving the performance of the range hood.

[0094] Furthermore, the adjusted flow area needs to be subjected to impedance calculation and ratio comparison again to ensure that the impedance of the adjusted silencer air duct 200 meets the requirements. This dynamic adjustment and feedback mechanism ensures the accuracy and effectiveness of the optimization process.

[0095] S22. If the ratio is less than or equal to or less than the preset ratio threshold, the flow area of ​​the muffler air duct 200 is not adjusted, and the current flow area is obtained.

[0096] It can be understood that when the ratio is less than, equal to or less than the preset ratio threshold, it means that the impedance of the silencer duct 200 is within a reasonable range. At this time, there is no need to further adjust the flow area. The unadjusted flow area is recorded as the current flow area, and then enters the next optimization step.

[0097] S3. Based on the current flow area, a preset optimized flow area is selected, and the change value of the sound power level and the change value of the sound transmission loss after the flow area is optimized are calculated respectively.

[0098] Specifically, based on the current flow area and the analysis of multiple groups of experimental data, it can be determined whether to further optimize by increasing the flow area or reducing the flow area. The specific increase or reduction can be selected according to the actual situation, and then the preset optimized flow area is determined. Among them, the sound-absorbing material is arranged in the silencer duct 200. When the outer dimensions of the range hood are limited, the sum of the flow area of ​​the silencer duct 200 and the cross-sectional area of ​​the sound-absorbing material is a fixed value, which means that there is a trade-off relationship between the two: when the flow area of ​​the silencer duct 200 increases, the cross-sectional area of ​​the sound-absorbing material will decrease accordingly; conversely, if the flow area of ​​the silencer duct 200 is reduced, the cross-sectional area of ​​the sound-absorbing material will increase. Therefore, to optimize the flow area of ​​the silencer duct 200 under such limited conditions, it is necessary to carefully consider the impact of the change in the flow area on the acoustic performance. Specifically, it is necessary to evaluate the change in the sound power level and the change in the sound transmission loss after the flow area is optimized, so as to determine the change in the noise level caused by the change in the flow area. Among them, the sound power level reflects the strength of the sound energy radiated by the sound source, while the sound transmission loss describes the degree of energy attenuation during the propagation of sound.

[0099] It should be noted that, compared with the current flow area of ​​the silencer air duct 200, the absolute value of the increase or decrease in the preset optimized flow area (i.e., the absolute value of the adjustment amount of the flow area) is smaller than the absolute value of the increase in the flow area of ​​the silencer air duct 200 preliminarily adjusted in step S21. In other words, steps S1 and S2 preliminarily optimize the flow area with a relatively large adjustment amount, and on this basis, steps S3 and S4 optimize the flow area again with a relatively small adjustment amount.

[0100] On the basis of the impedance of the silencer air duct 200 obtained above, the process of obtaining the change value of the sound power level after the flow area is optimized includes: based on the current flow area and the preset optimized flow area, respectively calculating the total impedance of the range hood before optimization and the total impedance after optimization, and constructing different characteristic curves of the fan 310 under the corresponding total impedance, and then under the rated working air volume, according to the characteristic curve of the fan 310, calculating the speed of the fan 310 before optimization and the speed of the fan 310 after optimization, and finally calculating the change value of the optimized sound power level based on the speed of the fan 310 before optimization and the speed of the fan 310 after optimization.

[0101] Specifically, the current flow area of ​​the muffler air duct 200 and the preset optimized flow area can be respectively input into the relationship model between the flow area and impedance of the simulated air duct to obtain the impedance of the muffler air duct 200 before optimization and the impedance after optimization, and then add the impedance of the smoke collecting component 100 and the impedance of the public flue 400 to obtain the total impedance of the range hood before optimization and the total impedance after optimization. By determining the total impedance of the range hood before optimization and the total impedance after optimization, the corresponding characteristic curve of the fan 310 under the corresponding total impedance is determined, and then under the condition of rated working air volume, the speed of the fan 310 before optimization and the speed after optimization can be obtained. Finally, according to formula (5), the optimized sound power level change value can be calculated. Formula (5) is as follows:

[0102]

[0103] Where ΔL is the change in sound power level in dB; n a is the speed of the fan 310 before optimization, in rpm; n b is the optimized rotation speed of the fan 310, in rpm; and m is a proportional constant.

[0104] It should be noted that the proportional constant m reflects the quantitative relationship between the change in sound power level and the change in speed ratio. It means that for every 1 dB change in sound power level, the logarithm of the corresponding speed ratio multiplied by m is equal to the change in sound power level. In other words, m is the proportional coefficient in the formula, and the value of m is based on experimental data or empirical formulas. For example, m can be 50.

[0105] Further, when the sum of the flow area of ​​the silencer air duct 200 and the cross-sectional area of ​​the sound absorbing material is a fixed value, that is, the total area is fixed, the cross-sectional area of ​​the sound absorbing material can be calculated by the flow area of ​​the silencer air duct 200. On the above basis, the process of obtaining the change value of the sound transmission loss after the flow area is optimized includes: calculating the current cross-sectional area of ​​the sound absorbing material based on the current flow area, and calculating the preset optimized cross-sectional area of ​​the sound absorbing material based on the preset optimized flow area, and then establishing a noise loss simulation model, respectively inputting the current cross-sectional area of ​​the sound absorbing material and the preset optimized cross-sectional area of ​​the sound absorbing material into the noise loss simulation model, and obtaining the optimized sound transmission loss change value through comparison.

[0106] S4. Compare the current flow area with the selected preset optimized flow area, compare the sound power level change value and the sound transmission loss change value, and determine the target flow area of ​​the silencer duct 200 based on the comparison result and the selected preset optimized flow area.

[0107] Specifically, step S4 includes:

[0108] S41. If the preset optimized flow area is smaller than the current flow area, and the increase in the sound power level is smaller than or equal to the increase in the sound transmission loss, the preset optimized flow area is determined as the target flow area of ​​the silencer duct 200.

[0109] It is understandable that if the preset optimized flow area is smaller than the current flow area, it means that the muffler air duct 200 is expected to be optimized by reducing the flow area. At this time, by comparing the increase in the sound power level with the increase in the sound transmission loss, it can be evaluated whether the noise level of the range hood increases or decreases when the flow area is reduced. Specifically:

[0110] When the sound power level change value is less than or equal to the sound transmission loss change value, this means that although the sound energy (sound power level) emitted by the sound source has increased, the attenuation of the sound during propagation (sound transmission loss) has also increased accordingly, and the degree of attenuation is sufficient to offset the increase in the sound source energy, and even makes the noise level that finally reaches the receiving point lower than before the optimization. Therefore, in this case, it can be determined that the preset optimized flow area meets the optimization conditions and can be determined as the target flow area of ​​the muffler duct 200.

[0111] S42. If the preset optimized flow area is smaller than the current flow area, and the increase in the sound power level is greater than or equal to or greater than the increase in the sound transmission loss, the preset optimized flow area is determined as the current flow area, and the process returns to step S3.

[0112] If the sound power level change value is greater than, equal to, or greater than the sound transmission loss change value, the increase in sound source energy will exceed the attenuation of sound during propagation, resulting in an increase in the noise level of the range hood when it is working compared to before optimization. At this time, the preset optimized flow area does not meet the optimization conditions, so the preset optimized flow area should be used as the new current flow area and the next round of optimization attempts should be repeated. Through the above process, the flow area of ​​the muffler duct 200 can be accurately adjusted to achieve the best balance between reducing noise and maintaining range hood performance.

[0113] In one embodiment, Figure 7 As shown, when the flow area of ​​the muffler air duct 200 is 50000mm 2 , the total impedance of the system is about 2.2, the speed is 1100rpm, the working point is point a in the figure, and the air volume is 11.6m 3 / min; when the flow area of ​​the silencer air duct 200 is 20000mm 2 When , the total impedance of the system is about 2.6. To achieve the same air volume, the speed needs to be increased to 1200rpm, and the working point is point b in the figure. m takes a value of 50. According to formula (5), the increase in the sound power level can be calculated to be 1.89dB. At this time, if the calculated increase in the sound transmission loss is greater than or equal to 1.89dB, it means that the optimization scheme meets the conditions, and the preset optimized flow area is determined as the target flow area of ​​the silencer duct 200; if the calculated increase in the sound transmission loss is less than or equal to 1.89dB, it means that the optimization scheme does not meet the conditions and needs to be further optimized.

[0114] S43. If the preset optimized flow area is larger than the current flow area, and the reduction value of the sound power level is larger than or equal to the reduction value of the sound transmission loss, the preset optimized flow area is determined as the target flow area of ​​the silencer duct 200.

[0115] Similarly, if the preset optimized flow area is larger than the current flow area, it means that the muffler air duct 200 is planned to be optimized by expanding the flow area. In this optimization process, by comparing the reduction in the sound power level with the reduction in the sound transmission loss, it is evaluated whether the noise level of the range hood increases or decreases after the flow area is expanded. Specifically:

[0116] When the reduction value of the sound power level is greater than or equal to the reduction value of the sound transmission loss, it means that the sound energy (sound power level) generated by the sound source is reduced, and the attenuation of the sound during propagation (i.e., the sound transmission loss) is also reduced accordingly, but the reduction in attenuation does not exceed the reduction in the sound power level, so the noise level that finally reaches the receiving point is reduced. In this case, the preset optimized flow area meets the optimization conditions and can be determined as the target flow area of ​​the muffler duct 200.

[0117] S44. If the preset optimized flow area is larger than the current flow area, and the reduction value of the sound power level is less than or equal to or less than the reduction value of the sound transmission loss, the preset optimized flow area is determined as the current flow area, and the process returns to step S3.

[0118] If the reduction in the sound power level is less than, equal to, or less than the reduction in the sound transmission loss, the noise generated by the optimized range hood during operation may increase compared to before the optimization. This is because the attenuation of sound during propagation is reduced more, resulting in an increase in the noise level that finally reaches the receiving point. In this case, the preset optimized flow area does not meet the optimization conditions because it causes an increase in the noise level. Therefore, the preset optimized flow area should be used as the new current flow area, and the next round of optimization attempts should be repeated. Through the above process, the flow area of ​​the silencer duct 200 can be accurately adjusted to achieve the best balance between reducing noise and maintaining range hood performance.

[0119] An embodiment of the present invention further provides a range hood, which includes a silencer air duct 200, and the silencer air duct 200 is designed by the flow area optimization method of the range hood silencer air duct 200 in any of the aforementioned technical solutions.

[0120] In summary, the present invention can preliminarily adjust the flow area of ​​the silencer duct 200 by limiting the proportion of the impedance of the silencer duct 200 in the total impedance of the smoke exhaust channel so that it does not exceed the preset ratio threshold. The result of this preliminary adjustment provides a data basis for subsequent optimization and adjustment, greatly reducing the error range. On this basis, a preset optimized flow area is further selected as a reference, and the change value of the sound power level and the change value of the sound transmission loss after the flow area is optimized are calculated. The changes in these two indicators provide an important basis for measuring the optimization effect. By comparing the change value of the sound power level and the change value of the sound transmission loss, the actual effect of the optimization can be more intuitively understood, and the flow area of ​​the silencer duct 200 can be adjusted more finely accordingly. After such an optimization process, an optimal flow area of ​​the silencer duct 200 can be finally determined. The range hood can be designed with the silencer duct 200 using the flow area, which can ensure the smoke exhaust efficiency while keeping the range hood at a lower noise level.

[0121] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A method for optimizing the flow area of ​​a range hood silencer air duct, characterized in that: The range hood comprises a smoke collecting component, a muffler air duct and a main box connected in sequence, thereby forming a smoke channel, and the smoke channel is connected to a common smoke channel, thereby forming a smoke exhaust channel, and the optimization method comprises: S1. respectively obtaining the impedance of the smoke collecting component, the impedance of the muffler air duct and the impedance of the common flue, calculating the total impedance, and calculating the ratio of the impedance of the muffler air duct to the total impedance; S2, comparing the ratio with a preset ratio threshold, and selectively and preliminarily adjusting the flow area of ​​the muffler air duct according to the comparison result to obtain a current flow area; S3. Based on the current flow area, a preset optimized flow area is selected, and a change value of the sound power level and a change value of the sound transmission loss after the flow area is optimized are calculated respectively; S4. Compare the current flow area with the selected preset optimized flow area, compare the sound power level change value with the sound transmission loss change value, and determine the target flow area of ​​the silencer duct based on the comparison result and the selected preset optimized flow area.

2. The method for optimizing the flow area of ​​the noise-reducing air duct of a range hood according to claim 1, characterized in that: The “selectively and preliminarily adjusting the flow area of ​​the muffler air duct to obtain the current flow area according to the comparison result” includes: S21, if the ratio is greater than or equal to the preset ratio threshold, increase the flow area of ​​the muffler air duct, and return to step S1; or S22. If the ratio is less than, equal to or less than the preset ratio threshold, the flow area of ​​the silencer air duct is not adjusted, and the current flow area is obtained.

3. The method for optimizing the flow area of ​​the sound-absorbing air duct of a range hood according to claim 1, characterized in that: The “determining the target flow area of ​​the muffler air duct based on the comparison result and the selected preset optimized flow area” includes: S41. If the preset optimized flow area is smaller than the current flow area, and the increase in the sound power level is smaller than or equal to the increase in the sound transmission loss, the preset optimized flow area is determined as the target flow area of ​​the muffler duct; or S42, if the preset optimized flow area is smaller than the current flow area, and the increase in the sound power level is greater than, equal to, or greater than the increase in the sound transmission loss, the preset optimized flow area is determined as the current flow area, and the process returns to step S3; or S43, if the preset optimized flow area is larger than the current flow area, and the reduction value of the sound power level is larger than or equal to the reduction value of the sound transmission loss, then the preset optimized flow area is determined as the target flow area of ​​the muffler air duct; or S44. If the preset optimized flow area is larger than the current flow area, and the reduction value of the sound power level is less than, equal to, or less than the reduction value of the sound transmission loss, the preset optimized flow area is determined as the current flow area, and the process returns to step S3.

4. The method for optimizing the flow area of ​​the noise reduction air duct of a range hood according to claim 1, characterized in that: The process of obtaining the impedance of the anechoic air duct is as follows: Constructing a simulated air duct and establishing a simulation model of the simulated air duct; Based on the simulation model of the simulated air duct, a simulation experiment is carried out, and the impedance of the anechoic air duct is calculated by analyzing the simulation results.

5. The method for optimizing the flow area of ​​the noise-absorbing air duct of a range hood according to claim 4, characterized in that: The simulated air duct includes a main duct and an expansion duct that are interconnected; There are two expansion pipes, which are respectively arranged at two ends of the main pipe; Wherein, the cross section of the section of the expansion pipe close to the main pipe is configured to be a structure that tapers outward from the main pipe.

6. The method for optimizing the flow area of ​​the sound-absorbing air duct of a range hood according to claim 4, characterized in that: The “conducting a simulation experiment based on the simulation model of the simulated air duct, and calculating the impedance of the anechoic air duct by analyzing the simulation results” includes: In the simulation model of the simulated air duct, a preset number of working conditions are selected, and the outlet pressure of each working condition is read; Based on the outlet pressure of each working condition, the resistance coefficient of the simulated air duct in each working condition is calculated, and a relationship model between the flow area and the resistance coefficient of the simulated air duct is fitted; Based on the relationship model between the flow area and the resistance coefficient of the simulated air duct, the impedance of the simulated air duct in each working condition is calculated, and the relationship model between the flow area and the impedance of the simulated air duct is established; The flow area of ​​the muffler air duct is input into the relationship model between the flow area and impedance of the simulated air duct to obtain the impedance of the muffler air duct.

7. The method for optimizing the flow area of ​​the noise-reducing air duct of a range hood according to claim 6, characterized in that: The "calculating the resistance coefficient of the simulated air duct in each working condition based on the outlet pressure of each working condition" is calculated by formula (1): Wherein, ΔP is the pressure loss value of the simulated air duct, ξ is the resistance coefficient of the simulated air duct, ρ is the air density, and v is the average wind speed of the simulated air duct; and / or The "calculating the impedance of the simulated air duct in each working condition based on the relationship model between the flow area and the resistance coefficient of the simulated air duct" is calculated by formula (2): Among them, S is the impedance of the simulated air duct, ξ is the resistance coefficient of the simulated air duct, ρ is the air density, and A is the cross-sectional area of ​​the simulated pipe.

8. The method for optimizing the flow area of ​​the sound-absorbing air duct of a range hood according to claim 6, characterized in that: A fan is provided in the main box, and the process of obtaining the change value of the sound power level after the flow area is optimized includes: Based on the current flow area and the preset optimized flow area, respectively calculating the total impedance of the range hood before optimization and the total impedance after optimization, and constructing different characteristic curves of the fan under the corresponding total impedance; Under the condition of rated working air volume, according to the characteristic curve of the fan, the speed of the fan before optimization and the speed of the fan after optimization are calculated; Based on the rotation speed of the fan before optimization and the rotation speed after optimization, the optimized sound power level change value is calculated.

9. The method for optimizing the flow area of ​​the sound-absorbing air duct of a range hood according to claim 1, characterized in that: The process of obtaining the change value of the acoustic transmission loss after the flow area is optimized includes: Calculating a current cross-sectional area of ​​the sound absorbing material based on the current flow area; Calculating a preset optimized cross-sectional area of ​​the sound absorbing material based on a preset optimized flow area; A noise loss simulation model is established, the current cross-sectional area of ​​the sound absorbing material and the preset optimized cross-sectional area of ​​the sound absorbing material are respectively input into the noise loss simulation model, and the optimized sound transmission loss change value is obtained through comparison.

10. A range hood, characterized in that: The range hood comprises a sound-absorbing air duct, and the sound-absorbing air duct is designed by the flow area optimization method of the range hood sound-absorbing air duct according to any one of claims 1 to 9.

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