Optimization method for combustion chamber ignition test conditions

Abstract

This invention provides a method for optimizing combustion chamber ignition test conditions, comprising: Step 1, establishing a baseline model for estimating the lean ignition boundary of the combustion chamber; Step 2, establishing a fitting formula for the lean ignition boundary of the combustion chamber based on discrete test data and the baseline model; Step 3, calculating the ignition boundary to form a hyperspace surface, forming an original set of operating conditions in space, such that the boundary corresponding to the operating points in the original set of operating conditions is a discrete point distributed on the hyperspace surface; Step 4, optimizing the original set of operating conditions to form an optimized set of operating conditions, and determining the final set of operating conditions based on the ignition boundary deviation requirements between the original set of operating conditions and the optimized set of operating conditions. This method for optimizing combustion chamber ignition test conditions can significantly reduce the number of test conditions and improve test efficiency.

Description

Technical Field

[0001] This invention relates to the field of aero-engine testing technology, and specifically to a method for optimizing combustion chamber ignition test conditions. Background Technology

[0002] Ignition performance is a crucial indicator for evaluating the main combustor of an aero-engine. The ignition performance of the main combustor is primarily obtained through testing, which simulates the high-altitude ignition environment by altering incoming flow parameters. Numerous factors influence the ignition performance of an aero-engine combustor, including inlet air temperature, inlet pressure, fuel flow rate, and the performance of the combustor head and nozzle. When these fundamental influencing factors interact, the workload of testing becomes substantial, even making it difficult to implement. For example, a single test of a certain engine under development involves 60 ignition performance test conditions, requiring three tests to meet verification requirements, with a test cycle of 7-10 days. Given the high number of tests and costs, there is an urgent need for combined optimization of test conditions. This optimization method should obtain the optimal solution that meets error requirements while ensuring verification indicators (the principle of minimizing the number of tests). Therefore, it is necessary to develop a method for optimizing combustor ignition test conditions to reduce the number of tests and lower testing costs. Summary of the Invention

[0003] In view of this, the embodiments of this specification provide a method for optimizing the operating conditions of combustion chamber ignition tests, so as to reduce the number of tests and reduce test costs.

[0004] This specification provides the following technical solution in its embodiments: a method for optimizing combustion chamber ignition test conditions, comprising: Step 1, establishing a baseline model for predicting the lean ignition boundary of the combustion chamber; Step 2, establishing a fitting formula for the lean ignition boundary of the combustion chamber based on discrete test data and the baseline model for predicting the lean ignition boundary of the combustion chamber; Step 3, calculating the ignition boundary to form a hyperspace surface, forming an original set of operating conditions in space, such that the boundary corresponding to the operating point in the original set of operating conditions is a discrete point distributed on the hyperspace surface; Step 4, optimizing the original set of operating conditions through ignition test conditions to form an optimized set of operating conditions, and determining the final set of operating conditions based on the ignition boundary deviation requirements between the original set of operating conditions and the optimized set of operating conditions.

[0005] Compared with existing technologies, the beneficial effects achieved by at least one of the above-mentioned technical solutions adopted in the embodiments of this specification include at least the following: A formula that meets the fitting accuracy requirements is obtained by combining a benchmark model of the lean ignition boundary of the combustion chamber with discrete test data, which can be used to predict the lean ignition boundary of the combustion chamber under test. Furthermore, this fitting formula is considered to have guiding significance for subsequent combustion chamber tests. By designing the operating condition optimization criteria and the evaluation standard between the operating condition set, an operating condition set that meets the accuracy requirements is obtained, significantly reducing the number of test conditions and improving test efficiency. Attached Figure Description

[0006] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0007] Figure 1 This is a flowchart illustrating an embodiment of the present invention;

[0008] Figure 2 This is a schematic diagram of the drawing of a two-dimensional working condition set in an embodiment of the present invention;

[0009] Figure 3 This is a schematic diagram of the drawing of a three-dimensional working condition set in an embodiment of the present invention;

[0010] Figure 4 This is a schematic diagram of the optimized operating point after removing point P3 in an embodiment of the present invention;

[0011] Figure 5 This is a schematic diagram of the optimized operating point after removing point P2 in an embodiment of the present invention. Detailed Implementation

[0012] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0013] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0014] like Figures 1 to 5 As shown, this embodiment of the invention provides a method for optimizing combustion chamber ignition test conditions, including the following steps:

[0015] Step 1: Establish a baseline model for predicting the lean ignition boundary in the combustion chamber;

[0016] Step 2: Based on discrete experimental data and the baseline model for predicting the lean ignition boundary of the combustion chamber, establish a fitting formula for the lean ignition boundary of the combustion chamber;

[0017] Step 3: Calculate the ignition boundary to form a hyperspace surface, forming the original working condition set in space, so that the boundary corresponding to the working condition points in the original working condition set is a discrete point distributed on the hyperspace surface.

[0018] Step 4: Optimize the original operating condition set by conducting ignition test to form an optimized operating condition set. Based on the ignition boundary deviation requirements between the original and optimized operating condition sets, determine the final operating condition set.

[0019] By employing a benchmark model of the lean ignition boundary in the combustion chamber combined with discrete experimental data, a formula meeting the required fitting accuracy is obtained, which can be used to predict the lean ignition boundary of the combustion chamber under test. Furthermore, this fitting formula is considered to have guiding significance for subsequent combustion chamber tests. By designing operating condition optimization criteria and evaluation standards between operating condition sets, an operating condition set meeting the accuracy requirements is obtained, significantly reducing the number of test conditions and improving test efficiency.

[0020] The specific implementation method is as follows:

[0021] There were originally 35 ignition test conditions for a certain type of combustion chamber, requiring two tests to obtain the ignition performance of the combustion chamber. In order to reduce the number of test conditions, shorten the verification cycle, and reduce energy consumption, the method of this invention is used to optimize the test conditions.

[0022] Implementation Step 1: Establish a benchmark model for the lean ignition boundary of the combustion chamber, and calculate the lean ignition boundary using Formula 1:

[0023]

[0024] In the formula: P3 is the total pressure of the combustion chamber inlet air, T3 is the total temperature of the combustion chamber inlet air, W3 is the flow rate of the combustion chamber inlet air, α is the lean ignition boundary of the combustion chamber, and C1, C2, C3, and C4 are the corresponding coefficients, which need to be determined through specific combustion chamber ignition test results. Specifically, the open-source code MIConvexHull can be used to calculate the convex hull of the operating condition set. This code also includes a functional module for triangulating the interior points.

[0025] Step 2: Based on previous test data of similar combustion chambers, the formula was fitted to obtain Formula 2. The absolute error of the residual gas coefficient fitting of this fitted formula is ±0.18, and the relative error is ±10%, both of which meet the requirements of industry standards, indicating that the fitted formula can be used for subsequent analysis.

[0026] The accuracy meets the requirements of subsequent analysis.

[0027]

[0028] Step 3:

[0029] The ignition boundary is calculated using an empirical model to form a hyperspace surface S, which in turn forms a set of operating conditions in space. The operating condition points correspond to discrete points distributed on S, such as... Figure 2 and Figure 3 As shown.

[0030] Step 4:

[0031] Establish optimization criteria for ignition test conditions: optimize internal points first, then optimize boundary points, and prioritize the removal of points with small curvature changes on the boundary.

[0032] like Figure 4 and Figure 5 As shown, optimizing point P3 does not affect the shape of the original curve, but optimizing point P2 will change the shape of the original curve. Therefore, point P3 can be optimized, but point P2 cannot be optimized.

[0033] The ignition boundary deviation requirement between the original and optimized operating condition sets is set at ±10%. According to relevant industry standards, an ignition boundary deviation within 10% is acceptable; therefore, the current deviation is set at ±10%.

[0034] The optimized set of operating conditions is determined based on the deviation, as follows:

[0035] Original operating condition set: 35 operating condition points;

[0036] Operating condition set 1: 28 points, 7 points were optimized away;

[0037] Working condition set 2: 21 points, 14 points were optimized away;

[0038] Working condition set 3: 14 points, 21 points were optimized away;

[0039] As shown in Tables 1 and 2, the results show that the points that were optimized out did not affect the final fitting formula. In other words, the test results obtained from 14 working points were almost completely consistent with those obtained from 35 working points, and the deviation met the set index requirement of less than 10% (in fact, they were all within 7%). Therefore, working set 3, i.e., 14 working points, can be used for subsequent tests.

[0040] Table 1 - Optimization details of ignition test conditions for a certain type of combustion chamber

[0041]

[0042]

[0043] Table 2 - Summary of Prediction Deviations Between Operating Case Sets

[0044]

[0045]

[0046] The above description is merely a specific embodiment of the present invention and should not be construed as limiting the scope of the invention. Therefore, any substitution of equivalent components or equivalent changes and modifications made within the scope of protection of this patent should still fall within the scope of this patent. Furthermore, the technical features, technical features and technical solutions, and technical solutions in this invention can be freely combined and used.

Claims

1. A method for optimizing combustion chamber ignition test conditions, characterized in that, include: Step 1: Establish a baseline model for predicting the lean ignition boundary in the combustion chamber; Step 2: Based on discrete experimental data and the baseline model for predicting the lean ignition boundary of the combustion chamber, establish a fitting formula for the lean ignition boundary of the combustion chamber; Step 3: Calculate the ignition boundary to form a hyperspace surface, forming the original working condition set in space, so that the boundary corresponding to the working condition points in the original working condition set is a discrete point distributed on the hyperspace surface. Step 4: Optimize the original operating condition set by performing ignition test conditions to form an optimized operating condition set. Determine the final operating condition set based on the ignition boundary deviation requirements between the original and optimized operating condition sets. The benchmark model for predicting the lean ignition boundary of the combustion chamber in step one is... Where P3 is the total pressure of the combustion chamber inlet air, T3 is the total temperature of the combustion chamber inlet air, W3 is the flow rate of the combustion chamber inlet air, α is the lean ignition boundary of the combustion chamber, and C1, C2, C3, and C4 are coefficients. In step four, the original operating condition set is optimized by performing ignition test conditions to form the optimized operating condition set, specifically as follows: Optimize from the interior points towards the boundary points; When optimizing boundary points, the curvature change of each boundary point is determined. When the curvature change of a boundary point is less than a set value, the boundary point is optimized away.

2. The method for optimizing combustion chamber ignition test conditions according to claim 1, characterized in that, Step two specifically involves: obtaining C1=0.00000002715, C2=-3.9, C3=3.0909, and C4=-3.22 through fitting discrete experimental data, and combining this with the baseline model for predicting the lean ignition boundary of the combustion chamber to obtain the fitting formula for the lean ignition boundary of the combustion chamber. .

3. The method for optimizing combustion chamber ignition test conditions according to claim 1, characterized in that, In step four, the ignition boundary deviation between the original operating condition set and the optimized operating condition set is required to be ±10%.

4. The method for optimizing combustion chamber ignition test conditions according to claim 3, characterized in that, If the ignition boundary deviation requirement between the original operating condition set and the optimized operating condition set is not met, repeat step four to optimize the ignition test operating condition of the original operating condition set to form the optimized operating condition set.

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