CN114647948A - Theoretical calculation method for resistance loss of underground exhaust fan room in deep-buried space - Google Patents
Theoretical calculation method for resistance loss of underground exhaust fan room in deep-buried space Download PDFInfo
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Abstract
The invention discloses a theoretical calculation method for resistance loss of an underground exhaust fan room in a deep-buried space, and relates to the technical field of ventilation of underground spaces. Aiming at the problems that the air duct structure of the exhaust fan room of the pumped storage power station is complex and the theoretical calculation is difficult, the reasonable correction coefficient is provided, the theoretical calculation result is corrected, the resistance of the exhaust fan rooms in different arrangement modes is determined by integrating the methods of the theoretical calculation, the numerical calculation and the secondary correction, and a general calculation formula of the resistance loss of the exhaust fan rooms is provided. The method is helpful for providing guidance for fan equipment selection of the exhaust fan room, and simplifies the calculated amount of numerical simulation.
Description
Technical Field
The invention belongs to the technical field of ventilation of underground spaces, and particularly relates to a theoretical calculation method for resistance loss of an underground exhaust fan room of a deep-buried space.
Background
The air flow organization of the deeply buried underground space plays a crucial role in the safety of the space environment, wherein the exhaust system is a key link of the air flow organization. Deeply buried underground spaces are widely present in cities (including subways, underground pipe galleries and underground warehouses), mines, pumped storage power stations (underground cavern groups) and the like. The underground cavern group of the pumped storage hydropower station belongs to a deeply buried underground building, and the main components of the underground cavern group comprise underground ventilation ducts such as a main power house, a bus duct, a main transformer duct, a traffic duct, a ventilation duct and the like and an exhaust system. And the ventilation and exhaust system of the pumped storage power station penetrates through the whole underground plant, wherein the ventilation system comprises a lower ventilation tunnel, a ventilation vertical shaft and a ventilation machine room. In order to meet the heat dissipation requirements of power generation equipment of a main plant and each room, 4-5 axial flow type exhaust fans are required to be arranged in parallel inside an exhaust fan room. Researches show that the energy consumption generated by the fan accounts for about 30-50% of the total energy consumption of the building. Therefore, the equipment type selection of the fan is critical, and unnecessary energy waste can be caused by too large type selection; the model selection is too small, and the requirement of air exhaust is difficult to meet; therefore, the corresponding exhaust fan must be selected by adopting a reasonable calculation method to solve the resistance loss of the exhaust fan room. Meanwhile, in the actual operation process, when a plurality of fans are operated in parallel, although the total air exhaust amount is increased, the total air exhaust amount is smaller than the sum of the air exhaust amounts when the fans are used independently, the fan efficiency is reduced, and therefore, the method for controlling the fans in parallel is very key to reduce the mutual influence among the fans by adopting a reasonable control method.
Regarding the calculation method of the resistance loss of the exhaust fan room, there are two main methods adopted in the design: theoretical calculation methods and numerical simulation methods. However, the two calculation methods have the following problems in practical use:
1) because the air duct structure of the exhaust fan room is complex, the resistance loss of the exhaust fan room is difficult to be solved by a theoretical calculation method, most of the design methods adopt empirical values, the loss of each meter in Pa is estimated, the estimation result is used, the equipment model selection is carried out by contrasting the relevant specifications, the result can cause the actual exhaust volume of the fan to be far lower than the design value, and the actual operation effect is greatly different from the expected value.
2) The method comprises the steps of carrying out physical modeling on the exhaust fan room by adopting a numerical simulation method, and then calculating resistance loss of the exhaust fan room through simulation software such as Fluent and the like. Aiming at different exhaust fan room structures, if an optimal solution is required to be obtained, a plurality of physical models are required to be established, so that the required time is long; and due to the problems of uncertainty of boundary conditions, selection of a turbulence model and the like, the problems of poor design and operation effects and the like can also be caused when the equipment model is selected according to the calculation result of the resistance loss of the exhaust system calculated by a numerical simulation method.
In the existing patent about the influence of the operation effect of the whole plant ventilation system:
the invention patent with the application number of 202010856702.5 provides a method for researching the air exhaust effect of an air exhaust system of an underground workshop of a pumped storage power station, the method takes the whole air exhaust system as a research object, and provides a method for simulating indoor and outdoor meteorological parameters and deducing relevant parameters in a prototype through a model test when the air exhaust system is subjected to the model test. The patent provides a method for measuring the resistance loss of an exhaust system, however, the detailed description on how to calculate the resistance loss of an exhaust fan room is not provided, and the analysis on factors influencing the exhaust effect is also lacked.
The invention patent with the application number of 202010284348.3 discloses an actuation line method for simulating the working flow field of an axial flow exhaust fan of an underground workshop of a pumped storage power station, which utilizes an actuation line model to carry out numerical calculation on an exhaust channel of the axial flow exhaust fan of the pumped storage power station. Although the problems of large number of grids and long calculation time exist when the axial flow exhaust fan of the underground factory building is subjected to solid modeling, the support in the aspect of theoretical calculation is lacked, and the research on the aspect of control strategy when a plurality of fans are operated in a combined mode is less.
When the air exhaust effect of the air exhaust fan room is analyzed, because the number of the started generator sets is large, the air exhaust amount of a single fan in operation is difficult to meet the requirement, and in actual engineering, 2-4 fans are often required to be started. However, fans are operated in parallel, although the air volume is increased to some extent, the air volume is smaller than the sum of the air volumes when the fans are used independently, the efficiency of the fans is reduced to some extent, and therefore it is very critical to adopt a reasonable control method to reduce the mutual influence between the fans, however, in the existing patents, the research on the aspect is lacked, and the actual fan starting mode is often started according to experience or at will, so that the working efficiency of the fans is low, and unnecessary energy waste is caused.
Disclosure of Invention
The invention aims to solve the technical problem of providing a theoretical calculation method for resistance loss of a deep-buried underground exhaust fan room, and solving the problems that an air duct structure of the exhaust fan room of a pumped storage power station is complex and is difficult to calculate theoretically.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows:
step one, reasonably simplifying the exhaust fan room model. The specific method comprises the following steps: simplifying the shape of the irregular cross section by adopting a mode of equivalent diameter, simplifying the upper arched cross section (ceiling) into a horizontal surface, obtaining a physical model after simplification, and carrying out theoretical calculation on the physical model to obtain the resistance loss of the exhaust fan room.
And step two, carrying out numerical calculation on the simplified physical model to obtain the resistance loss of the exhaust fan room under the same condition.
And step three, comparing the result obtained by theoretical calculation under the same condition with the result obtained by numerical calculation to obtain a numerical correction coefficient, wherein the numerical correction coefficient is used for correcting the result obtained by numerical calculation.
And fourthly, performing numerical simulation calculation on the prototype of the exhaust fan room to obtain the resistance loss of the exhaust fan room in the prototype.
And fifthly, comparing a result obtained by numerical calculation of the physical model of the simplified exhaust fan room with a result obtained by numerical calculation in the prototype to obtain a model correction coefficient under the same condition, wherein the model correction coefficient is used for correcting the result obtained by numerical calculation of the physical model.
And step six, correcting the result of numerical calculation according to the numerical correction coefficient and the model correction coefficient to obtain the theoretical calculation result of the resistance loss of the exhaust system.
The simplified physical model is theoretically calculated to obtain a calculation formula of the resistance loss of the exhaust fan room, wherein the calculation formula is as follows:
ΔPL＝SpQ2，
wherein, Δ pLIn order to obtain the resistance loss of the exhaust fan room by theoretical calculation of the physical model, SpIs the impedance of the pipeline, Q is the volume flow in the pipeline, lambda is the on-way resistance coefficient of the pipeline, l is the length of the pipeline, deIs the equivalent diameter of the pipeline, A is the cross-sectional area of the pipeline, epsilon is the local resistance coefficient of the pipeline, and rho is the density.
Preferably, when the resistance loss of the prototype of the exhaust fan room is calculated by adopting a numerical calculation method, the specific operation steps are as follows:
s1, establishing a numerical calculation model of the exhaust fan room prototype;
s2, taking the actual exhaust fan room as a prototype, establishing a reduced scale test bed for simulating the prototype and establishing a numerical calculation model of the reduced scale model test bed;
s3, calculating the resistance loss of the exhaust fan room prototype according to the numerical calculation model of the exhaust fan room and the input boundary conditions:
s4, calculating the resistance loss of the exhaust fan room of the reduced scale test bed according to the numerical calculation model of the reduced scale model test bed and the input boundary conditions;
s5, comparing the numerical calculation results of the exhaust fan room prototype and the reduced scale model test bed under the same condition, judging whether the difference value between the two is within an error range, and if so, taking the resistance loss of the exhaust fan room prototype as the numerical calculation result; if the two are not in the error range, the corresponding boundary conditions are modified, and the step S3 is returned to.
Preferably, the specific implementation manner of step S2 is:
selecting a geometric similarity ratio, establishing a reduced scale model test bed of a simulation prototype, and determining the absolute roughness according to the geometric similarity ratio when selecting the wall surface material of the reduced scale model test bed.
And (4) acquiring test data from the reduced scale model test bed, comparing the calculation result of the step S4, judging whether the calculation result is within an error range, and if not, adjusting corresponding boundary conditions according to a similarity criterion to ensure that the calculation result of the reduced scale model test bed is accurate.
Further, the specific calculation step in the sixth step is as follows:
firstly, theoretical calculation is carried out on a physical model of a simplified exhaust fan room to obtain the resistance loss delta P of the exhaust fan roomL(ii) a The physical model of the simplified exhaust fan room is numerically calculated to obtain the resistance loss delta P of the exhaust fan room under the same conditionsObtaining the numerical correction coefficient epsilon1The numerical correction factor ε1The expression of (a) is:
then, carrying out numerical simulation calculation on the prototype of the exhaust fan room to obtain the resistance loss delta P of the exhaust fan room in the prototypenUnder the same condition, comparing the result obtained by numerical calculation of the physical model of the simplified rear exhaust fan room with the result obtained by numerical calculation in the prototype to obtain the model correction coefficient epsilon2The model correction coefficient ε2Is expressed as
Finally, root ofAccording to the value, correcting the coefficient epsilon1And a model correction coefficient ε2Calculating the result delta P of the prototype value of the exhaust fan roomnCorrected to obtain the calculation result delta P of the original resistance loss of the exhaust fan roomL', calculation result of prototype resistance loss of the exhaust fan room Delta PLThe expression is: delta PL'＝ε1ε2ΔPL。
Numerical correction factor epsilon1And a model correction coefficient ε2The characteristic curve of the exhaust system pipe network is only related after the characteristic curve is determined by the method. Aiming at the control strategy of the parallel operation of a plurality of fans, the technical route adopted by the invention is as follows:
when a plurality of fans are operated in parallel, the position unbalance rate eta of the fans is taken as a characteristic value, different eta values represent different fan starting modes, and the position unbalance rate eta expression is as follows:
wherein, | Δ d | is the relative position difference between the center of the fan group and the center of the exhaust inlet in the length direction, and L is the distance from the inlet of the exhaust fan room to the farthest end of the exhaust fan room.
And carrying out numerical calculation on the resistance of the exhaust fan room when the plurality of fans are operated in parallel, comparing the resistance loss when the plurality of fans are operated in parallel, and analyzing the influence of the position unbalance rate eta of the plurality of fans on the resistance loss of the exhaust fan room. The position unbalance rate eta and the opening mode when the fans are operated in parallel are displayed in a chart form.
Adopt the produced beneficial effect of above-mentioned technical scheme to lie in:
1. aiming at the problems that the air duct structure of the exhaust fan room of the pumped storage power station is complex and theoretical calculation is difficult to use, a reasonable correction coefficient is provided, the theoretical calculation result is corrected, and the theoretical calculation method for the resistance loss of the exhaust fan room in different arrangement modes is determined by comprehensively considering the methods of theoretical formula calculation, numerical simulation analysis and secondary correction.
2. The influence of different fan opening modes on the resistance of the exhaust fan room when a plurality of fans are operated in parallel is analyzed, and the problem that the resistance loss of a complex air duct is difficult to solve by the conventional theoretical calculation method is solved. The method is helpful for providing guidance suggestions for fan equipment type selection of the fan exhaust room, and provides scientific basis for reducing the resistance of the air exhaust system and improving the ventilation energy-saving potential of the pumped storage power station.
Drawings
FIG. 1 is an overall flow chart of the present invention;
FIG. 2 is an isometric view of an original form of an exhaust room of a Yimeng pumped-hydro power plant in an embodiment;
FIG. 3 is a sectional view of an embodiment of a Yimeng pumped-hydro energy storage plant ventilator house fan exhausting to a cross-section;
FIG. 4 is an axonometric view of a physical model of a pumped storage power station after simplification processing in an embodiment;
FIG. 5 is a diagram illustrating velocity profiles corresponding to different fan turn-on modes in the embodiment;
FIG. 6 is a pressure distribution diagram corresponding to imbalance ratios at different positions.
In the figure: 1. an exhaust inlet; 2. an air exhaust duct; 3. a first exhaust fan; 4. a second exhaust fan; 5. a third exhaust fan; 6. a fourth exhaust fan; 7. an air exhaust shaft inlet; 8. and an air exhaust vertical shaft.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
Referring to fig. 1-5, a theoretical calculation method for researching resistance loss of an air exhaust system of an underground workshop of a deep-buried space comprises the following steps:
the method comprises the following steps of firstly, simplifying a model of the exhaust fan room to obtain a simplified physical model, and carrying out theoretical calculation on the physical model to obtain the resistance loss of the exhaust fan room;
step two, carrying out numerical calculation on the simplified physical model to obtain the resistance loss of the exhaust fan room under the same condition;
comparing calculation results obtained by theoretical formula calculation and numerical calculation under the same condition to obtain a numerical correction coefficient, wherein the numerical correction coefficient is used for correcting the result obtained by numerical calculation;
fourthly, performing numerical simulation calculation on the prototype of the exhaust fan room to obtain the resistance loss of the exhaust fan room in the prototype;
comparing a result obtained by numerical calculation of the simplified physical model of the exhaust fan room with a result obtained by numerical calculation in the prototype to obtain a model correction coefficient under the same condition, wherein the model correction coefficient is used for correcting the result obtained by numerical calculation of the physical model;
and step six, obtaining a theoretical calculation result of the resistance loss of the exhaust system according to the numerical correction coefficient and the result of the numerical correction of the model correction coefficient.
The simplified physical model obtained by simplifying the exhaust fan room means that the parallel exhaust duct in the exhaust fan room prototype is simplified into an exhaust duct, the inlet 7 of the exhaust vertical shaft is simplified into a 90-degree elbow, and the resistance is replaced by local resistance.
Further, as a specific embodiment, when the physical model of the exhaust fan room is theoretically calculated, the following operations are performed:
obtaining the resistance loss delta PL of the exhaust fan room by adopting theoretical calculation, wherein the calculation formula of the resistance loss delta PL is as follows: delta PL＝SpQ2In which S ispQ is the line impedance and the volume flow in the line. Pipeline impedance SpThe calculation formula of (2) is as follows:
wherein, lambda is the on-way resistance coefficient of the pipeline, l is the length of the pipeline, deIs the equivalent diameter of the pipeline, A is the cross-sectional area of the pipeline, epsilon is the local resistance coefficient of the pipeline, and rho is the density.
Further, as a specific embodiment, when a numerical calculation method is used to perform numerical calculation on the exhaust fan room prototype, the specific embodiment is as follows:
s1, establishing a numerical calculation model of the exhaust fan room prototype;
s2, taking the actual exhaust fan room as a prototype, establishing a reduced scale test bed for simulating the prototype and establishing a numerical calculation model of the reduced scale model test bed;
s3, calculating the resistance loss of the exhaust fan room prototype according to the numerical calculation model of the exhaust fan room and the input boundary conditions:
s4, calculating the resistance loss of the exhaust fan room of the reduced scale test bed according to the numerical calculation model of the reduced scale model test bed and the input boundary conditions;
s5, comparing the numerical calculation results of the exhaust fan room prototype and the reduced scale model test bed under the same condition, judging whether the difference value between the two is within an error range, and if so, taking the resistance loss of the exhaust fan room prototype as the numerical calculation result; if the two are not in the error range, the corresponding boundary conditions are modified, and the process returns to the step S3.
Further, the specific implementation manner of step S2 is:
and selecting a geometric similarity ratio, establishing a reduced scale model test bed of a simulation prototype, and determining the absolute roughness according to the geometric similarity ratio when selecting the wall surface material of the reduced scale model test bed.
And (4) acquiring test data from the reduced scale model test bed, comparing the calculation result of the step S4, judging whether the calculation result is within an error range, and if not, adjusting corresponding boundary conditions according to a similarity criterion to ensure that the calculation result of the reduced scale model test bed is accurate.
Further, the coefficient ε is corrected according to the value1And the model correction coefficient ε2Correcting the result of numerical calculation to obtain the theoretical calculation result of the resistance loss of the exhaust system, and the method comprises the following specific steps of:
theoretical calculation is carried out on the physical model of the simplified exhaust fan room to obtain the resistance loss delta P of the exhaust fan roomL(ii) a The physical model after the exhaust fan room is simplified is subjected to numerical calculation to obtain the sameConditioned exhaust fan house resistance loss delta PsTo obtain a numerical correction coefficient epsilon1Numerical correction factor ε1The expression of (a) is:
further, carrying out numerical simulation calculation on the prototype of the exhaust fan room to obtain the resistance loss delta P of the exhaust fan room in the prototypenUnder the same condition, comparing the result obtained by numerical calculation of the physical model of the simplified rear exhaust fan room with the result obtained by numerical calculation in the prototype to obtain the model correction coefficient epsilon2Coefficient of model correction ε2The expression is as follows:
further, the coefficient ε is corrected according to the value1And a model correction coefficient ε2Calculating the result delta P of the prototype value of the exhaust fan roomnCorrected to obtain the calculation result delta P of the original resistance loss of the exhaust fan roomL', calculation result of original resistance loss of exhaust fan room Delta PLThe expression is: delta PL'＝ε1ε2ΔPL。
Further, as a specific implementation manner, the method further comprises a fan parallel operation control strategy:
when a plurality of fans are operated in parallel, the position unbalance rate eta of the fans is taken as a characteristic value, and the expression of the position unbalance rate eta is as follows:
wherein, | Δ d | is the relative position difference between the center of the fan group and the center of the exhaust inlet 1 in the length direction, and L is the length from the inlet of the exhaust fan room to the farthest end of the exhaust fan room.
Further, the resistance of the exhaust fan room is calculated by combining the numerical correction coefficient epsilon when a plurality of fans are operated in parallel1And a model correction coefficient ε2And the resistance loss of the multiple fans in parallel operation is obtained.
Furthermore, the resistance loss when the fans are operated in parallel is compared, and the influence of the position unbalance rate eta of the fans on the resistance loss of the exhaust fan room is analyzed.
The invention is further described with reference to the drawings and the specific embodiments in the following description.
The method aims to solve the problems that the air duct structure of the exhaust fan room is complex, the resistance loss of the exhaust fan room is difficult to accurately solve by using a theoretical calculation method and the like in the prior art. The invention provides a method for determining the resistance loss of a fan exhaust room by comprehensively considering theoretical formula calculation, numerical calculation and secondary correction, and provides a control strategy when a plurality of fans are operated in parallel.
Taking a certain pumped storage power station in Shandong as an example, the exhaust system mainly comprises an exhaust shaft 8 of an underground factory building, an exhaust air duct 2 and a ground exhaust machine room platform. The sub-plant ventilating machine room and the main sub-plant ventilating machine room are connected below the underground plant ventilating shaft 8, the upper side is connected with the air exhaust air channel 2, the section is circular, the inner diameter is 7.0m, and the height is 208.87 m. The air exhaust duct 2 is connected with an air exhaust vertical shaft 8 and a main exhaust fan room, the main exhaust fan room is arranged at the opening of the air exhaust duct 2, the net size of the section is 7.0 multiplied by 6.0m, and the length of the tunnel is 377.30 m. The elevation of the total exhaust fan room platform of the section of the exhaust air duct 2 is 350.00m, and the platform size is 37.0 multiplied by 19.0 m.
1. Calculating a physical model after simplifying the exhaust fan room by adopting the existing theoretical empirical formula to obtain the resistance loss force delta P of the exhaust fan roomL。
ΔPLThe calculation formula of (2) is as follows: delta PL＝SpQ2In which S ispQ is the line impedance and the volume flow in the line. Pipeline impedance SpThe calculation formula of (2) is as follows:
wherein, lambda is the on-way resistance coefficient of the pipeline, l is the length of the pipeline, and deIs the equivalent diameter of the pipeline, A is the cross-sectional area of the pipeline, epsilon is the local resistance coefficient of the pipeline, and rho is the density.
Further, the equivalent diameter d of the pipeeThe calculation formula of (2) is as follows:
wherein A is the area of the cross section of the pipeline, and chi is the wet circumference.
Further, the local resistance coefficient epsilon of the pipeline comprises a local resistance which is suddenly expanded and a local resistance coefficient epsilon which is suddenly reduced2Sudden expansion of the local drag coefficient ε1The calculation formula of (2) is as follows:
wherein, A1The area of the cross section of the pipeline before diameter changing, A2The area of the section of the pipeline after diameter change; suddenly reduced local drag coefficient epsilon2The calculation formula of (2) is as follows:
wherein, A1To the cross-sectional area of the pipeline after diameter change, A2The area of the section of the pipeline before diameter changing.
Further, when the fluid flowing state in the exhaust fan chamber is turbulent, the expression of the on-way resistance coefficient lambda in different turbulent flow areas is as follows:
turbulent smooth zone:
a turbulent flow transition zone:
turbulent rough area:
in the above format, Re is the reynolds number; d is the equivalent diameter of the pipeline, and the unit is m; k is the absolute roughness of the wall surface, the unit is mm, the wall surface structure of the exhaust fan room is a concrete pipe, and the K value is 0.3-3.0.
2. And on the premise that the boundary conditions of the theoretical formula are the same, calculating the resistance loss of the simplified exhaust fan room by using a numerical calculation method.
3. Theoretical calculation is carried out on the physical model of the simplified exhaust fan room to obtain the resistance loss delta P of the exhaust fan roomL(ii) a The physical model of the simplified exhaust fan room is numerically calculated to obtain the resistance loss delta P of the exhaust fan room under the same conditionsTo obtain a numerical correction coefficient epsilon1Numerical correction factor ε1The expression of (a) is:
4. further, numerical simulation calculation is carried out on the prototype of the exhaust fan room to obtain the resistance loss delta P of the exhaust fan room in the prototypenUnder the same condition, comparing the result obtained by numerical calculation of the physical model of the simplified rear exhaust fan room with the result obtained by numerical calculation in the prototype to obtain the model correction coefficient epsilon2Coefficient of model correction ε2The expression is as follows:
5. further, the coefficient epsilon is corrected according to the numerical value1And the model correction coefficient ε2Calculating the result delta P of the prototype value of the exhaust fan roomnCorrected to obtain the calculation result delta P of the original resistance loss of the exhaust fan roomL', calculation result of original resistance loss of exhaust fan room Delta PLThe expression is: delta PL'＝ε1ε2ΔPL。
In order to ensure the accuracy of the numerical calculation result, especially when the numerical calculation is carried out on the exhaust fan room prototype, the result accuracy directly influences the numerical correction coefficient epsilon1The accuracy of (2). The accuracy of the numerical calculation method can be ensured by the following steps:
1) establishing a numerical calculation model of the exhaust fan room prototype;
2) selecting a proper geometric similarity ratio by taking an actual exhaust fan room as a prototype, building a reduced scale test bed for simulating the prototype, selecting a material with the roughness corresponding to the prototype according to the similarity ratio, and building a numerical calculation model of the reduced scale model test bed;
3) because the proportion of the inertia force and the buoyancy lift force of the prototype and the scale model is different, when the scale model is built, the larger value of the influence factors is considered, and the larger value is taken as the decisive influence factor;
4) calculating the resistance loss of the exhaust fan room of the reduced scale test bed according to the numerical calculation model of the reduced scale model test bed and the input boundary conditions;
5) comparing the numerical calculation results of the exhaust fan room prototype and the reduced scale model test bed under the same condition, judging whether the difference value between the two is within an error range, and if so, taking the resistance loss of the exhaust fan room prototype as the numerical calculation result; if the two are not in the error range, modifying the corresponding boundary conditions, and returning to the step 2.
The numerical calculation results under each working condition are verified through experimental data obtained by the reduced scale model under the corresponding working condition, so that the reliability of the results is ensured.
And (4) acquiring test data from the reduced scale model test bed, comparing the calculation result in the step (4), judging whether the calculation result is in an error range, and if not, adjusting corresponding boundary conditions according to a similarity criterion to ensure that the calculation result of the reduced scale model test bed is accurate.
Further, the settlement result by adopting the method is as follows:
further, in the embodiment, the method further comprises a control strategy for parallel operation of the fans, and the specific content is as follows:
when a plurality of fans are operated in parallel, taking the position unbalance rate eta of the plurality of fans as a characteristic value, wherein the expression of the position unbalance rate eta is as follows:
wherein, | Δ d | is the relative position difference between the center of the fan group and the center of the exhaust inlet 1 in the length directionAnd L is the distance from the inlet of the exhaust fan room to the farthest end of the exhaust fan room.
The specific number of the fans and the starting condition are shown in table 1:
TABLE 1 specific number of blowers and starting condition table
(attached: fan on table is 1; fan off is 0)
Further, the resistance of the exhaust fan room is calculated by combining the numerical correction coefficient epsilon when a plurality of fans are operated in parallel1And a model correction coefficient ε2And the resistance loss of the multiple fans in parallel operation is obtained.
Furthermore, the resistance loss when the fans are operated in parallel is compared, and the influence of the position unbalance rate eta of the fans on the resistance loss of the exhaust fan room is analyzed.
FIG. 6 is a pressure distribution diagram corresponding to imbalance ratios at different locations.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be able to cover the technical scope of the present invention and the equivalent alternatives or modifications according to the technical solution and the inventive concept of the present invention within the technical scope of the present invention.
Claims (5)
1. A theoretical calculation method for resistance loss of underground exhaust fan rooms in deep buried space is characterized by comprising the following steps:
the method comprises the following steps of firstly, simplifying a model of the exhaust fan room to obtain a simplified physical model, and carrying out theoretical calculation on the physical model to obtain the resistance loss of the exhaust fan room;
step two, carrying out numerical calculation on the simplified physical model to obtain the resistance loss of the exhaust fan room under the same condition;
comparing a result obtained by theoretical calculation under the same condition with a result obtained by numerical calculation to obtain a numerical correction coefficient, wherein the numerical correction coefficient is used for correcting the result obtained by numerical calculation;
fourthly, carrying out numerical simulation calculation on the prototype of the exhaust fan room to obtain the resistance loss of the exhaust fan room in the prototype;
comparing a result obtained by numerical calculation of the simplified physical model of the exhaust fan room with a result obtained by numerical calculation in the prototype to obtain a model correction coefficient under the same condition, wherein the model correction coefficient is used for correcting a result obtained by numerical calculation of the physical model;
and step six, obtaining a theoretical calculation result of the resistance loss of the exhaust system according to the numerical correction coefficient and the result of the numerical correction of the model correction coefficient.
2. The theoretical calculation method for resistance loss of an underground exhaust fan room in a deep-buried space according to claim 1, wherein in the fourth step, when a numerical calculation method is adopted to calculate the prototype resistance loss of the exhaust fan room, the concrete operation steps are as follows:
s1, establishing a numerical calculation model of the exhaust fan room prototype;
s2, taking the actual exhaust fan room as a prototype, establishing a reduced scale test bed for simulating the prototype and establishing a numerical calculation model of the reduced scale model test bed;
s3, calculating the resistance loss of the exhaust fan room prototype according to the numerical calculation model of the exhaust fan room and the input boundary conditions:
s4, calculating the resistance loss of the exhaust fan room of the reduced scale test bed according to the numerical calculation model of the reduced scale model test bed and the input boundary conditions;
s5, comparing the numerical calculation results of the exhaust fan room prototype and the reduced scale model test bed under the same condition, judging whether the difference value between the two is within an error range, and if so, taking the resistance loss of the exhaust fan room prototype as the numerical calculation result; if the two are not in the error range, the corresponding boundary conditions are modified, and the process returns to the step S3.
3. The theoretical calculation method for resistance loss of an underground exhaust fan room in a deep-buried space according to claim 2, wherein the specific implementation manner of the step S2 is as follows:
selecting a geometric similarity ratio, establishing a reduced scale model test bed of a simulation prototype, and determining the absolute roughness according to the geometric similarity ratio when selecting a wall surface material of the reduced scale model test bed;
and (4) acquiring test data from the reduced scale model test bed, comparing the calculation result of the step S4, judging whether the calculation result is within an error range, and if not, adjusting corresponding boundary conditions according to a similarity criterion to ensure that the calculation result of the reduced scale model test bed is accurate.
4. The theoretical calculation method for resistance loss of the underground exhaust fan room of the deep-buried space according to claim 1, wherein the concrete calculation steps in the sixth step are as follows:
firstly, theoretical calculation is carried out on a physical model of a simplified exhaust fan room to obtain the resistance loss delta P of the exhaust fan roomL(ii) a The physical model of the simplified exhaust fan room is numerically calculated to obtain the resistance loss delta P of the exhaust fan room under the same conditions(ii) a Obtaining the numerical correction coefficient epsilon1The numerical correction factor ε1The expression of (a) is: epsilon1＝
Then, carrying out numerical simulation calculation on the prototype of the exhaust fan room to obtain the resistance loss delta P of the exhaust fan room in the prototypenUnder the same condition, comparing the result obtained by numerical calculation of the physical model of the simplified rear exhaust fan room with the result obtained by numerical calculation in the prototype to obtain the model correction coefficient epsilon2The model correction coefficient ε2Is expressed as
Finally, the coefficient epsilon is corrected according to the numerical value1And a model correction coefficient ε2Calculating the result delta P of the numerical value of the exhaust fan room prototypenCorrected to obtain the calculation result delta P of the original resistance loss of the exhaust fan roomL', calculation result of prototype resistance loss of the exhaust fan room Delta PLThe expression is: delta PL'＝ε1ε2ΔPL。
5. The method as claimed in claim 4, wherein the coefficient of correction epsilon is used to calculate the resistance loss of underground exhaust fan room1And the model correction coefficient ε2Analyzing the control mode when the plurality of fans are operated in parallel to obtain the resistance loss of the exhaust fan room and the positive coefficient epsilon of the numerical correction coefficient when the plurality of fans are operated in parallel1Model correction factor ε2And the relationship between the positional imbalance ratio η.
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