Heat flow density distribution and temperature distribution acquisition method

Abstract

The application relates to a heat flow density distribution and temperature distribution acquisition method, and particularly provides a heat flow density acquisition method for an anti-icing inner surface of an air inlet channel, which is based on the geometric relationship that a jet hole center, a center of a pipe section of a flute-shaped pipe and a jet stagnation point on the anti-icing surface are collinear, the jet stagnation point position on the anti-icing inner surface of the air inlet channel is determined according to the jet hole position and the flute-shaped pipe position, the jet hole diameter and the distance from the jet hole to the anti-icing inner surface are determined, a Nusselt number calculation formula is determined according to jet flow heat gas parameters of the flute-shaped pipe, the convection heat exchange coefficient distribution near the jet stagnation point is calculated according to the Nusselt number calculation formula and the jet stagnation point position, and the heat flow density value distribution of the anti-icing inner surface is calculated according to the jet flow temperature value, the anti-icing inner surface temperature initial value and the convection heat exchange coefficient distribution. The above method can simplify the heat flow density distribution acquisition process and improve the calculation efficiency. The application also provides a temperature distribution acquisition method for an anti-icing surface of an air inlet channel.

Description

Technical Field

[0001] This invention relates to the field of aero-engines, and more specifically to the field of engine anti-icing. Background Technology

[0002] Ice formation on the surface of the engine nacelle air intake can lead to problems such as reduced airflow area and decreased engine thrust. In severe cases, it can even cause dangerous conditions like compressor surge, resulting in catastrophic accidents. Therefore, an air intake anti-icing system is a crucial means of ensuring the quality of the engine intake airflow and the safe operation of the aircraft in icing environments.

[0003] Currently, the main method for anti-icing the engine nacelle intake is piccolo tube anti-icing. This method involves drawing hot air from the engine compressor to a piccolo tube at the leading edge of the intake duct, and then expelling the hot air through jet holes on the piccolo tube, thus heating the leading edge of the intake duct lip. Piccolo tube anti-icing systems have advantages such as good anti-icing effect, wide application, high maturity, and relatively low bleed air volume requirements. However, there are numerous design configuration parameters for piccolo tube anti-icing systems. To accurately obtain the intake anti-icing surface temperature under different configurations, compare the anti-icing effects of nacelle piccolo tube anti-icing systems under different configurations, and complete the selection of the piccolo tube anti-icing cavity design scheme, it is necessary to conduct three-dimensional internal and external flow coupling heat transfer simulation calculations for the nacelle intake anti-icing system.

[0004] Due to the complex internal flow of the air intake structure, including the flute-shaped tube, the jet impact process is affected by factors such as the nozzle shape, the distance between the nozzle and the wall, the jet exit angle, and multiple arrays. Traditional numerical calculation methods construct internal and external grid flow fields simultaneously inside and outside the nacelle air intake, and obtain the simulated temperature distribution of the air intake through complex calculations and internal-external flow coupling processes. This numerical calculation method consumes a large amount of computational resources and time, severely impacting the efficiency of nacelle air intake anti-icing system design optimization and evaluation. Therefore, it is necessary to propose a calculation method to solve the above problems. Summary of the Invention

[0005] One object of the present invention is to provide a method for obtaining heat flux density, which simplifies the method of obtaining heat flux density of the anti-icing inner surface and avoids complex calculations.

[0006] The method for obtaining heat flux density distribution to achieve the above objective is used to obtain the heat flux density distribution on the inner surface of the air intake anti-icing system, and includes the following steps: S1. Based on the geometric relationship that the center of the jet orifice, the center of the flute-shaped pipe section, and the jet stagnation point located on the inner surface of the anti-icing system are collinear, the position of the jet stagnation point on the inner surface of the air intake anti-icing system is determined by the position of the jet orifice and the position of the flute-shaped pipe; S2. The diameter of the jet orifice and the distance from the jet orifice to the inner surface of the anti-icing system are determined, and the Nusselt number calculation formula is determined according to the hot gas parameters of the flute-shaped pipe jet; S3. According to the Nusselt number calculation formula and the position of the jet stagnation point, the convective heat transfer coefficient distribution near the jet stagnation point is calculated; S4. According to the jet inflow temperature value, the initial temperature value of the inner surface of the anti-icing system, and the convective heat transfer coefficient distribution, the heat flux density value distribution on the inner surface of the anti-icing system is calculated.

[0007] In one or more embodiments, the method further includes determining the positional and structural parameters of the flute tube before performing step S1, and determining the jet hot gas parameters of the flute tube before performing step S2.

[0008] In one or more embodiments, the Nusselt number calculation formula in step S2 is obtained by manual identification or by a calculation program.

[0009] In one or more embodiments, the Nusselt number is the orifice impingement jet Nusselt number.

[0010] Another objective of this invention is to provide a method for obtaining temperature distribution, which simplifies the acquisition of temperature distribution on the anti-icing surface of the air intake and effectively solves problems such as the complexity of the three-dimensional jet flow field simulation process of the nacelle air intake flute tube anti-icing system, the complexity of the internal and external thermal coupling heat transfer calculation process, and the long simulation calculation cycle.

[0011] The temperature distribution acquisition method for achieving the above objective is used to acquire the temperature distribution of the intake anti-icing surface, including the following steps: obtaining the heat flux density distribution of the inner surface of the anti-icing using the above-mentioned method for acquiring the heat flux density of the inner surface of the intake anti-icing, and using the heat flux density distribution of the inner surface of the anti-icing as the boundary condition of the inner surface of the intake anti-icing; determining the total heat transfer coefficient distribution and the outflow temperature of the outer surface of the intake anti-icing, and setting them as the boundary condition of the outer surface of the intake anti-icing; performing iterative calculations of the temperature field of the solid domain of the intake anti-icing until the calculation converges to obtain the temperature distribution of the intake anti-icing surface.

[0012] In one or more embodiments, the anti-icing surface temperature needs to be initialized before iterative calculations are performed.

[0013] In one or more embodiments, if the surface temperature calculation results do not converge, the convective heat transfer coefficient distribution and heat flux density distribution of the anti-icing inner surface are recalculated using the updated intake anti-icing inner surface temperature results, and the temperature field of the intake anti-icing solid domain is iteratively calculated again until the calculation converges.

[0014] The aforementioned method for obtaining heat flux density distribution uses the geometric relationship that the center of the jet orifice, the center of the flute-shaped tube cross-section, and the jet stagnation point on the anti-icing surface are collinear to find the location of the jet stagnation point on the inner surface. It then obtains the Nusselt number calculation formula using the jet hot gas parameters and flute-shaped tube structural parameters. Furthermore, it uses the Nusselt number calculation formula to obtain the convective heat transfer coefficient distribution near the jet stagnation point and the heat flux density distribution on the inner surface of the anti-icing system. This eliminates the need for traditional methods of constructing internal and external flow fields and performing coupled simulations. Therefore, it can easily and quickly obtain the heat flux density distribution on the inner surface and then apply it to the temperature distribution formula on the anti-icing surface to obtain the temperature distribution. This solves the problems of complex calculation processes and long simulation cycles in the nacelle inlet flute-shaped tube anti-icing system, effectively improving computational efficiency. Attached Figure Description

[0015] The above and other features, properties and advantages of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings and embodiments, wherein:

[0016] Figure 1 This is a flowchart of a method for obtaining the heat flux density and temperature distribution on the inner surface of the anti-icing system.

[0017] Figure 2 This is a schematic diagram showing the position of the flute-shaped tube. Detailed Implementation

[0018] The present invention will be further described below with reference to specific embodiments and accompanying drawings. More details are set forth in the following description in order to provide a full understanding of the present invention. However, the present invention can obviously be implemented in many other ways different from those described herein. Those skilled in the art can make similar extensions and derivations based on actual application situations without departing from the spirit of the present invention. Therefore, the scope of protection of the present invention should not be limited by the content of this specific embodiment.

[0019] It should be noted that these and other accompanying drawings are merely examples and are not drawn to scale, and should not be construed as limiting the scope of protection of the present invention.

[0020] The most common method for anti-icing the engine nacelle air intake is the flute-tube hot gas anti-icing method. Combined with... Figure 2 As shown in the schematic diagram of the flute-shaped tube position, the flute-shaped tube 30 is located in the anti-icing cavity 40 of the air intake and is one of the core components of the hot gas anti-icing system. The air intake is defined by the skin 15, which includes an inner surface and an outer surface. The outer surface can be regarded as the anti-icing outer surface 10, and the inner surface can be regarded as the anti-icing inner surface 20. The anti-icing outer surface 10 and the anti-icing inner surface 20 are collectively referred to as the anti-icing surface.

[0021] The flute-shaped tube 30 includes an inner cavity and an outer wall. Point O is the center of the cross-section of the flute-shaped tube, which is also the center of the inner cavity. Multiple jet holes 31 are provided on the outer wall, such as... Figure 2 Points A, B, and C are shown in the diagram. The jet orifice 31 connects the inner cavity of the flute-shaped tube 30 with the external anti-icing cavity 40. With the help of the pressure difference between the inside and outside of the flute-shaped tube, the hot air in the inner cavity is drawn out from the jet orifice 31, forming a jetting airflow F, which is sprayed onto the anti-icing inner surface 20, forming different jet stagnation points 33 on the anti-icing inner surface 20, as shown in A', B', and C', thereby providing the anti-icing thermal load required by the anti-icing system.

[0022] In traditional simulation calculations, it is generally necessary to construct two types of mesh flow fields inside and outside the anti-icing cavity. That is, to simultaneously construct the flow field mesh of the flow field where the anti-icing cavity 40 is located and the flow field mesh outside the anti-icing cavity 40, and to perform the internal three-dimensional jet complex flow field calculation process and the three-dimensional internal and external flow coupling calculation process to obtain the temperature distribution of the anti-icing surface. However, this method consumes a lot of computing resources and computing time, and is inefficient.

[0023] The method for obtaining the heat flux density on the inner surface of the air intake anti-icing surface as described in this disclosure can effectively simplify the calculation method, obtain the heat flux density distribution result of the inner surface of the ice in a simple and quick way, and further simplify the method of obtaining the temperature distribution of the anti-icing surface.

[0024] This method combines Figure 1 As illustrated in the flowchart, the first step, S1, involves determining the position of the jet stagnation point on the anti-icing surface of the air intake based on the collinear geometric relationship between the center of the jet orifice, the center of the flute-shaped tube cross-section, and the jet stagnation point on the anti-icing surface. It can be understood that the positional and structural parameters of the flute-shaped tube are determined before step S1 to determine the position of the jet orifice 31 and the position of the center O of the flute-shaped tube cross-section.

[0025] Specifically, taking jet orifice C as an example, according to Figure 2 It can be seen that the geometric relationship between the center O of the flute-shaped tube cross-section, the jet orifice C on the flute-shaped tube 30, and C on the anti-icing inner surface 20 is that the three points are collinear, and the jet flow is as shown in F. Therefore, based on the known jet orifice location data, the center data of the flute-shaped tube cross-section, and according to... Figure 2 The dotted-dash line shown can be used to easily and simply locate the positions of multiple jet stagnation points 33 on the inner surface of the anti-icing system.

[0026] After obtaining the location of the jet stagnation point 33, proceed to step S2 to determine the diameter d of the jet orifice 31 and the distance H from the jet orifice to the anti-icing inner surface, and determine the Nusselt number calculation formula based on the flute-shaped tube jet hot gas parameters. Since the diameter of the jet orifice 31 is generally small, the Nusselt number calculation formula is the same as the small-orifice impingement jet Nusselt number calculation formula. Before proceeding to step S2, it is necessary to determine the flute-shaped tube jet hot gas parameters, which mainly include jet hot gas temperature, pressure, and flow rate.

[0027] The distance H from the jet hole to the anti-icing inner surface 20 is as follows Figure 2 As shown. The jet orifice diameter d and the distance H from the jet orifice to the anti-icing inner surface 20 are important bases for obtaining the Nusselt number calculation formula. The Nusselt number calculation formula is a phased empirical formula, therefore, it is necessary to determine the Nusselt number calculation formula for small-hole impact jet based on the ratio of the distance H to the diameter d. For example, in one embodiment, when the ratio ranges from 2 ≤ H / d ≤ 12, and the Reynolds number Re ranges from 61000 ≤ Re ≤ 124000, the Nusselt number calculation formula is: In other embodiments, the Nusselt number calculation formula is determined based on the specific dimensions and the value of Re. Specifically, the Nusselt number calculation formula can be selected based on the content described in "Streamwise distribution of the recovery factor and the local heat transfer coefficient to animpinging circular air jet" (Goldstein, RJ, Behbahni, A.A. and Heppelman, KK, 1986).

[0028] Determining a suitable formula for calculating the Nusselt number is fundamental for rapid evaluation. In one embodiment, the Nusselt number formula is obtained either manually or through a calculation program. For example, the formula can be determined manually by reading a table and then inputting the calculation level. Alternatively, a stage function can be designed and implemented to directly obtain the Nusselt number formula determined by the ratio of distance H to diameter d within the program.

[0029] Continue with step S3. Based on the Nusselt number calculation formula obtained above and the location of the jet stagnation point 33, calculate the distribution of the three-dimensional convective heat transfer coefficient h near the jet stagnation point 33.

[0030] The relationship between the Nusselt number calculation formula and the convective heat transfer coefficient h is Nu = hd / K, where Nu is the aforementioned Nusselt number, h is the convective heat transfer coefficient, d is the jet orifice diameter, and K is the thermal conductivity of the fluid. The distribution data of the convective heat transfer coefficient h near the jet stagnation point 33 can be obtained using the above formula. Furthermore, according to the above formula and the aforementioned Nusselt number calculation formula, based on known data such as the jet orifice diameter d, the distance H from the jet orifice to the anti-icing inner surface 20, and the Reynolds number Re, the convective heat transfer coefficient h values ​​at various locations that gradually change radially outward from the jet stagnation point 31 can be calculated. The "nearby" refers to the range of the area requiring heat transfer calculation that gradually changes radially from the jet stagnation point 33.

[0031] Continue with step S4. Based on the temperature value of the jet flow F, the initial temperature value T0 of the anti-icing inner surface, and the distribution data of the convective heat transfer coefficient h mentioned above, calculate the heat flux density distribution of the anti-icing inner surface. The heat flux density distribution can be used to determine the degree of heat transfer at each location on the anti-icing inner surface.

[0032] In the above method of obtaining heat flux density, the location of the jet stagnation point on the inner surface is found by the collinear geometric relationship of the center of the jet hole, the center of the flute-shaped tube cross section, and the jet stagnation point on the anti-icing surface. The Nusselt number calculation formula is obtained by the jet hot gas parameters and flute-shaped tube structural parameters. Then, the convective heat transfer coefficient distribution near the jet stagnation point and the heat flux density distribution on the inner surface of the anti-icing surface are obtained by the Nusselt number calculation formula. This method no longer relies on the traditional method of constructing internal and external flow fields and performing coupled simulation calculations. Therefore, it can easily and quickly obtain the heat flux density distribution on the inner surface, effectively improving the calculation efficiency.

[0033] Based on the above introduction to the methods for obtaining heat flux density distribution, we can also understand a method for obtaining the temperature distribution of the inlet anti-icing surface. This method can simplify the acquisition of the temperature distribution of the inlet anti-icing surface, thereby solving problems such as the complexity of the three-dimensional jet flow field simulation process of the nacelle inlet flute tube anti-icing system, the complexity of the internal and external thermal coupling heat transfer calculation process, and the long simulation calculation cycle.

[0034] In this method, the heat flux density distribution of the anti-icing inner surface is obtained through the above-described heat flux density distribution acquisition method, and the obtained heat flux density distribution of the anti-icing inner surface is used as the boundary condition of the intake duct anti-icing inner surface 20, as shown in step S5. In one embodiment, the heat flux density distribution is used as a thermodynamic second-type condition boundary, that is, as a constant heat flux boundary, and is assigned to the intake duct anti-icing inner surface 20.

[0035] In addition, step S6 is required to determine the overall heat transfer coefficient distribution of the inlet duct anti-icing outer surface 10 and the temperature of the outflow gas G, and to set the boundary conditions for the inlet duct anti-icing outer surface 10. For example... Figure 2As shown, the outer region of the inlet anti-icing outer surface 10 is the area where external airflow G exists. The anti-icing outer surface 10 exhibits multiple heat transfer mechanisms. The total heat transfer coefficient distribution refers to the composite heat transfer coefficient, including surface convection heat transfer, heat energy converted from the kinetic energy of subcooled water droplet impacts, latent heat of subcooled water droplet heating, and evaporative cooling. The external airflow temperature is the airflow temperature near the anti-icing outer surface. Specifically, the boundary conditions for the inlet anti-icing outer surface can be set by importing a three-dimensional inlet anti-icing solid domain mesh file into CFD calculation software, along with the total heat transfer coefficient distribution data and external airflow temperature data.

[0036] The order of step S6, which determines the boundary of the anti-icing outer surface, and step S5, which determines the boundary conditions of the inner surface, is not specified.

[0037] After obtaining the inner and outer boundary conditions of the anti-icing surface, iterative calculations of the temperature field of the solid domain of the air intake anti-icing are performed until the calculation converges and the temperature distribution of the air intake anti-icing surface is obtained, as shown in step S7.

[0038] If the surface temperature calculation results do not converge, as in step S8, the convective heat transfer coefficient distribution and heat flux density distribution of the anti-icing inner surface are recalculated using the updated intake anti-icing inner surface temperature results, and the temperature field of the intake anti-icing solid domain is iterated again until the calculation converges.

[0039] In one embodiment, the anti-icing solid domain refers to the area where the skin 15 is located. After determining the calculation boundary conditions inside and outside the skin, iterative calculations can be performed within the anti-icing solid domain until convergence is achieved to obtain the overall temperature distribution of the intake anti-icing surface.

[0040] In one embodiment, the anti-icing surface temperature needs to be initialized before iterative calculations to ensure accurate calculations. The initialization value is determined based on the specific operating conditions.

[0041] In this method, numerical calculations only need to be performed in a portion of the flow field, eliminating the need to establish large-scale internal and external flow domain grids. Subsequent calculations also do not require an internal flow domain grid. Therefore, complex jet flow field simulations and internal and external flow thermo-coupling heat transfer calculations are unnecessary, effectively reducing calculation time, saving computational resources, significantly improving the efficiency of anti-icing surface temperature assessment, and enhancing the design and selection efficiency of nacelle flute tube anti-icing systems.

[0042] This application uses specific terms to describe embodiments of the application. Terms such as "an embodiment," "one embodiment," and / or "some embodiments" refer to a particular feature, structure, or characteristic associated with at least one embodiment of the application. Therefore, it should be emphasized and noted that references to "an embodiment," "one embodiment," or "an alternative embodiment" in different locations throughout this specification do not necessarily refer to the same embodiment. Furthermore, certain features, structures, or characteristics in one or more embodiments of the application can be appropriately combined.

[0043] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Any variations and modifications can be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, any modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention, without departing from the scope of the invention, fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for obtaining heat flux density distribution, used to obtain the heat flux density distribution on the inner surface of the air intake anti-icing system, characterized in that, Includes the following steps: S1. Based on the geometric relationship that the center of the jet hole, the center of the flute-shaped pipe section, and the jet stagnation point located on the anti-icing inner surface are collinear, the position of the jet stagnation point on the anti-icing inner surface of the air intake is determined by the position of the jet hole and the position of the flute-shaped pipe. S2. Determine the diameter of the jet orifice and the distance from the jet orifice to the anti-icing inner surface, and determine the Nusselt number calculation formula based on the hot gas parameters of the flute tube jet; S3. Calculate the convective heat transfer coefficient distribution near the jet stagnation point based on the Nusselt number calculation formula and the location of the jet stagnation point; S4. Calculate the heat flux density distribution of the anti-icing inner surface based on the jet inflow temperature, the initial temperature of the anti-icing inner surface, and the convective heat transfer coefficient distribution.

2. The method for obtaining heat flux density distribution as described in claim 1, characterized in that, The method also includes determining the position and structural parameters of the flute tube before performing step S1, and determining the jet hot gas parameters of the flute tube before performing step S2.

3. The method for obtaining heat flux density distribution as described in claim 1, characterized in that, The Nusselt number calculation formula described in step S2 is obtained either through manual identification or through a calculation program.

4. The method for obtaining heat flux density distribution as described in claim 1, characterized in that, The Nusselt number is the Nusselt number for small-hole impact jet.

5. A method for obtaining temperature distribution, used to obtain the temperature distribution of the anti-icing surface of the air intake duct, characterized in that, Includes the following steps: The heat flux density distribution of the anti-icing inner surface is obtained using the heat flux density acquisition method of the intake anti-icing inner surface as described in any one of claims 1-4, and the heat flux density distribution of the anti-icing inner surface is used as the boundary condition of the intake anti-icing inner surface. Determine the total heat transfer coefficient distribution and outflow temperature of the air intake anti-icing outer surface, and set them as the boundary conditions for the air intake anti-icing outer surface; Iterative calculations of the temperature field in the solid domain of the air intake anti-icing system are performed until the calculations converge to obtain the temperature distribution on the air intake anti-icing surface.

6. The method for obtaining temperature distribution as described in claim 5, characterized in that, Before performing iterative calculations, the anti-icing surface temperature needs to be initialized.

7. The method for obtaining temperature distribution as described in claim 5, characterized in that, If the surface temperature calculation results do not converge, the convective heat transfer coefficient distribution and heat flux density distribution of the anti-icing inner surface are recalculated using the updated intake anti-icing inner surface temperature results, and the temperature field of the intake anti-icing solid domain is iterated again until the calculation converges.

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