Method for determining critical throwing orientation of borneol and ice ingestion analysis method for aeroengine

Abstract

The present disclosure relates to a method for determining the critical throwing orientation of ice flakes and an ice ingestion analysis method for an aeroengine. Among them, the method for determining the critical throwing orientation of ice flakes includes: calculating the helix parameters at different blade heights on the leading edge of the blade and establishing a helix; establishing a cutting surface between the leading edges of two adjacent blades; establishing a geometric model of the ice flake; calculating the maximum axial distance that the ice flake can advance between the blades; offsetting the leading edge line of the blade axially by the maximum axial distance in the direction of ice flake movement, and then rotating this curve around the engine axis to obtain the boundary surface at the maximum axial position; rotating the curve at the blade tip around the engine axis to obtain the envelope toroid at the maximum radial position; assembling the ice flake between two adjacent cutting surfaces, the boundary surface at the maximum axial position, and the envelope toroid at the maximum radial position, while making the distance between the centroid of the ice flake and the engine axis as close as possible to the radius of the blade tip; obtaining the critical throwing orientation of the ice flake according to the assembly result.

Description

Technical Field

[0001] The present disclosure relates to a method for determining the key throwing orientation of ice flakes and an ice ingestion analysis method for an aeroengine. Background Art

[0002] The statements herein only provide background information related to the present disclosure and do not necessarily constitute prior art.

[0003] Ice ingestion by an aeroengine is an inevitable event during aircraft flight. Once an aeroengine ingests ice, it may damage structures such as the engine fan blades and compressor blades, resulting in surges or even engine flameout, seriously threatening flight safety. In response to the safety consequences caused by ice ingestion by aeroengines, airworthiness authorities such as the Federal Aviation Administration (FAA) of the United States, the European Union Aviation Safety Agency (EASA), and the Civil Aviation Administration of China (CAAC) have put forward airworthiness requirements for aeroengine ice ingestion. The specific clauses are the ice ingestion airworthiness requirements of FAR33.77, CS-E780, and CCAR33.77 respectively. The requirements of these airworthiness clauses are the same, that is, after the engine ingests ice, the resulting continuous power or thrust loss shall not be greater than 1.5%; the engine shall not stop; or no other abnormal conditions that may cause it to exceed its operating limits or structural limits shall occur. The FAA provides Advisory Circular AC20-147A for the FAR33.77 ice ingestion test, clearly stating that when the applicant conducts an analysis, the most critical ice flake attitude should be adopted, unless the applicant can show that for the purpose of the ice ingestion test, other ice flake attitudes are more conservative. The attitude of the ice flakes will significantly affect the impact load on the engine blades. Two ice flake attitudes in Advisory Circular AC20-147A result in different outcomes. As Figure 1 shown, the ice flake attitude on the left will cause 6-7 blades to share the impact load of the entire ice flake, and the ice flake attitude on the right will cause 3 blades to share the impact load of the entire ice flake.

[0004] In the related art, there is little public information on determining the critical attitude of ice flakes. There is only the paper "Numerical Simulation and Verification of Ice Impact on Aeroengine Fan Blades" by Hou Liang. Hou Liang used the method of Design of Experiments (DOE) + optimization to determine the critical throwing attitude of ice flakes. The rotation angles around the three coordinate axes of the Cartesian rectangular coordinate system were taken as optimization variables, and the sum of the plastic strains after the blade impact was taken as the optimization objective function. A spatial filling method was used to establish 346 models of different ice flake throwing attitudes and perform impact dynamics numerical calculations. Then, a response surface was constructed using a feedforward neural network model, and the most dangerous ice flake attitude was obtained using an adaptive simulated annealing optimization algorithm. As is well known, the impact of ice flakes on high-speed rotating blades is a highly nonlinear process. It is very likely that some critical ice flake attitudes will be missed using the spatial filling method. For such a highly nonlinear problem, the safest DOE method is the full factorial method, that is, the control variable method. If 10 parameter values are taken for each of the rotation angles along the three coordinate axes, then there will be 10 * 10 * 10 ice flake attitude models. Completing these 1000 impact dynamics calculations will consume a large amount of time and computing resources, and the obtained most dangerous ice flake attitude is only for the characteristics such as the blade size, shape, material, number of blades, and rotational speed in the calculation. Different blades require a large amount of recalculation.

[0005] However, the attitude of the ice flake only defines the angular information around the three coordinate axes and does not consider the position information when the ice flake impacts the blade. During the actual ice ingestion process of the engine, the same ice flake throwing attitude may also lead to different impact results. For example, Figure 2 as shown, the same ice flake throwing attitude leads to two possible situations where one blade bears the impact load of the ice flake or two blades share the impact load of the ice flake.

[0006] Therefore, in addition to considering the attitude of the ice flake, it is also necessary to consider the impact position between the ice flake and the blade, that is, to consider the throwing orientation of the ice flake. After adding three position information as optimization variables and using the full factorial method with 10 parameter values for each variable, then 10^6 ice flake throwing orientation models will be obtained. Whether it is calculated using impact dynamics or verified through experiments, it will consume huge resources and time. Summary of the Invention

[0007] One technical problem to be solved by the present disclosure is to provide a method for determining the critical throwing orientation of ice flakes and an ice ingestion analysis method for aeroengines, which can quickly evaluate the impact damage caused by ice flakes to the engine and blades.

[0008] A method for determining the critical throwing orientation of ice flakes according to an embodiment of the present disclosure includes the following steps:

[0009] S1: Calculate the helix parameters at different blade heights at the leading edge of the blade according to the blade rotational speed and the axial velocity of the ice flake, and establish a helix;

[0010] S2: Construct the cutting surface of the blade leading edge through multiple established helical curves;

[0011] S3: Establish the cutting surfaces of the leading edges of two adjacent blades;

[0012] S4: Determine the size of the ice chip according to the area of the engine nacelle lip and establish the geometric model of the ice chip;

[0013] S5: Calculate the maximum axial distance that the ice chip can advance between the blades according to the number of blades in one revolution, the blade rotation speed, and the ice chip speed;

[0014] S6: Axially offset the blade leading edge line by the maximum axial distance of the ice chip movement, and then rotate this curve around the engine axis to obtain the boundary surface at the maximum axial position;

[0015] S7: Rotate the curve at the blade tip around the engine axis to obtain the envelope toroidal surface at the maximum radial position;

[0016] S8: Assemble the ice chip between two adjacent cutting surfaces, the boundary surface at the maximum axial position, and the envelope toroidal surface at the maximum radial position, and at the same time make the distance between the centroid of the ice chip and the engine axis as close as possible to the radius of the blade tip;

[0017] S9: Obtain the critical throwing azimuth of the ice chip according to the assembly result.

[0018] In some embodiments, in step S1, the helix direction is the same as the blade rotation direction, the radius r of the helix is the distance between the impact point and the engine axis, and the pitch of the helix is 2π×r×tan(A) = 2π×v / ω.

[0019] In some embodiments, the multiple helical curves include at least 10 helical curves.

[0020] In some embodiments, in step S4, the ice chip size is obtained by interpolation according to the provisions of FAR33.77, and the geometric model of the ice chip is established.

[0021] According to an ice ingestion analysis method for an aeroengine provided by an embodiment of the present disclosure, it includes the method for determining the critical throwing azimuth of the ice chip as described above.

[0022] The method for determining the critical throwing azimuth of the ice chip in the present disclosure can determine the critical ice chip azimuth, so as to quickly conduct tests or numerical calculations to evaluate the ice ingestion ability of the engine and the impact resistance of the blade against the ice chip, effectively saving calculation costs and time costs. Through experimental verification, the ice chip throwing azimuth determined by this method is true and effective. Description of the Drawings

[0023] To more clearly illustrate the technical solutions in the embodiments of the present disclosure or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present disclosure. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0024] Figure 1 Schematic diagram of the influence on the attitude of the ice sheet;

[0025] Figure 2 and Figure 3 Both are schematic diagrams of the influence on the throwing position of the ice sheet;

[0026] Figure 4 Schematic diagram of the resultant velocity of the blade relative to the ice sheet;

[0027] Figure 5 Schematic diagram of the relative motion trajectory of the blade and the ice sheet in the method for determining the key throwing orientation of the ice sheet according to the present disclosure;

[0028] Figure 6 Schematic diagram of the boundary surface of the maximum axial position constructed by the method for determining the key throwing orientation of the ice sheet according to the present disclosure;

[0029] Figure 7 Developed view of the toroidal surface with equal rotation radius in the method for determining the key throwing orientation of the ice sheet according to the present disclosure;

[0030] Figure 8 Schematic diagram of the blade cutting surface constructed by the method for determining the key throwing orientation of the ice sheet according to the present disclosure;

[0031] Figure 9 Flowchart of the method for determining the key throwing orientation of the ice sheet according to the present disclosure. Detailed implementation manners

[0032] Now, various exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The description of the exemplary embodiments is merely illustrative and in no way limits the present disclosure and its application or use. The present disclosure can be implemented in many different forms and is not limited to the embodiments here. These embodiments are provided to make the present disclosure thorough and complete, and to fully convey the scope of the present disclosure to those skilled in the art. It should be noted that: unless otherwise specifically stated, the relative arrangements of components and steps, the composition of materials, numerical expressions and values set forth in these embodiments should be construed as merely exemplary and not as limitations.

[0033] As used in this disclosure, terms such as "first", "second" and the like do not denote any order, quantity or importance, but are merely used to distinguish different parts. Terms such as "comprising" or "including" mean that the elements before such term cover the elements listed after such term, and do not exclude the possibility of also covering other elements. Terms such as "upper", "lower", "left", "right" etc. are only used to indicate relative positional relationships, and when the absolute position of the object being described changes, such relative positional relationships may also change accordingly.

[0034] In this disclosure, when it is described that a specific device is located between a first device and a second device, there may or may not be an intermediate device between the specific device and the first device or the second device. When it is described that a specific device is connected to other devices, the specific device may be directly connected to other devices without an intermediate device, or may not be directly connected to other devices but have an intermediate device.

[0035] All terms used in this disclosure have the same meanings as those understood by ordinary technicians in the field to which this disclosure pertains, unless otherwise specifically defined. It should also be understood that terms defined in general dictionaries should be interpreted as having meanings consistent with their meanings in the context of the relevant technology, and should not be interpreted in an idealized or overly formal sense, unless specifically defined as such herein.

[0036] Technologies, methods and devices known to ordinary technicians in the relevant field may not be discussed in detail, but where appropriate, the technologies, methods and devices should be regarded as part of the specification.

[0037] Through the inventors' research, it has been found that there is no fast and efficient method for determining the throwing orientation of key ice flakes in the related art. The impact of ice flakes on a high-speed rotating blade is a transient and highly non-linear impact dynamics problem. Using a surrogate model to optimize the throwing orientation of key ice flakes may miss the key throwing orientations of ice flakes. To ensure the accuracy of the surrogate model, a large number of impact dynamics models need to be calculated as sample points, and the computational and time costs are high. To obtain the solution to a highly non-linear problem more accurately and convincingly, using the full factorial method to establish a surrogate model will incur huge computational and time costs. If each variable takes M parameter values, the total number of models is M^6, which is a huge-scale solution. When establishing sample points for different orientations of ice flakes, automated methods such as experimental design cannot guarantee that the generated throwing orientations of ice flakes are real and effective. For example, the ice flakes may interfere with the blade while remaining intact.

[0038] In order to quickly evaluate the impact damage caused by ice flakes to the engine and the blade, a method for quickly and efficiently determining the key throwing orientation of ice flakes is proposed, and the main idea is as follows:

[0039] Since the process of the ice particle impacting the engine rotor blade B is very short, generally on the order of milliseconds, it can be considered that when the impact occurs, the rotor blade B rotates around the rotor axis at a constant speed ω, and the ice particle moves along the rotor axis direction at a constant speed v. As Figure 4 shown, the tangential velocity of any point on the blade B is u = ω×r, where r is the rotational radius of this point from the rotor axis. The resultant velocity of any point on the blade B relative to the ice particle is The angle A between the resultant velocity and the tangential velocity is A = tan -1 (v / ω×r). Therefore, the closer to the blade tip, the smaller the angle A.

[0040] Since the blade B is in rotational motion and the ice particle is in axial linear motion, the relative motion trajectory of the ice particle and the blade B is a spatial helix H, as Figure 5 shown. The helix direction of the helix H is the same as the rotation direction of the blade B. The radius of the helix H is the radius r between the impact point and the engine axis, and the pitch of the helix H is 2π×r×tan(A) = 2π×v / ω.

[0041] The total number of blades B in one circle is N, then the angle between two adjacent blades B is 2π / N, and the time difference of rotation between adjacent blades B is (2π) / N / ω. The leading edge of the blade B is the edge line of the blade B that is the most air - intake - side in the axial direction. After the leading edge of the blade B rotates around the axis, a leading - edge surface is formed. When foreign objects enter the leading - edge surface of the blade B, they may be cut by the leading edge of a certain blade B. When the foreign object just misses the leading edge of one blade B and moves inward and is cut by the leading edge of the next blade B, the distance that the foreign object moves in the axial direction is the largest. This maximum axial distance is L = v×(2π) / N / ω. Offset the leading - edge line of the blade B by the axial distance L in the direction of the ice - particle movement, and rotate this curve around the engine axis to obtain the boundary surface F of the maximum axial position, as Figure 6 shown. The ice particle should be on the leading - edge side of the blade B and should not exceed this surface.

[0042] Take a toroidal surface with an equal rotational radius at a certain blade height position on the leading edge of the fan blade B and expand it into a plane, as Figure 7 shown. The distance between the relative motion trajectories of the leading edges of adjacent blades B relative to the ice particle is: It can be seen that the closer to the blade tip, the larger the distance D. On this plane, if the foreign object falls between the motion trajectories of the leading edges of these two blades B, the entire foreign object will impact one blade B.

[0043] After making the relative trajectory lines at different blade heights on the leading edge of one blade B, if they are taken densely enough along the blade height direction, these trajectory lines become a trajectory surface, that is, the relative motion trajectory surface of the leading edge of the blade B relative to the ice particle, which can be understood as the trajectory surface for the leading edge of the blade B to cut the ice particle. Here it is called the boundary surface S of the leading edge of the blade B. Make the cutting surfaces of adjacent blades B, as Figure 8As shown, there is a space between adjacent cutting surfaces. Within this space, the object will not be cut by the leading edges of adjacent blades B, and an entire ice sheet impacts onto one blade B.

[0044] Considering from the perspective of kinetic energy where m is the mass of the impact object and v r is the relative velocity of the impact object relative to the object being impacted, it is necessary to make the ice sheet impact onto one blade B as much as possible. The extreme case is that the entire ice sheet impacts one blade B.

[0045] The velocity of the ice sheet is a constant value. The tangential velocity at the tip of blade B is greater. Considering from the perspective of kinetic energy, the ice sheet should impact the tip part of blade B where the tangential velocity is large.

[0046] The ice sheet is brittle under high-speed impact. To avoid the fragments after the ice sheet breaks not impacting onto blade B, at the moment when the ice sheet impacts blade B, the radius of any point on the ice sheet to the engine axis should not exceed the radius of the tip. Therefore, rotating the curve of the blade B tip around the engine axis to obtain the enveloping toroidal surface of the maximum radial position, and the ice sheet should fall within this toroidal surface.

[0047] The tangential velocity at the tip is the largest, and the spacing between adjacent cutting surfaces at the tip is the largest. Therefore, the ice sheet should be placed at the tip as much as possible. Assemble the ice sheet between two adjacent boundary surfaces S, the boundary surface F at the maximum axial position, and the enveloping toroidal surface at the maximum radial position. At the same time, make the radius of the centroid of the ice sheet to the engine axis as close as possible to the radius of the tip. In this way, the ice sheet can avoid being cut by the previous blade B and impact onto the subsequent blade B as a whole. And the obtained spatial orientation of the ice sheet is the key ice sheet throwing orientation, which can be used for experiments or calculations to quickly evaluate the ice intake ability of the engine and the impact resistance ability of blade B against the ice sheet.

[0048] Based on the above ideas, an embodiment of the present disclosure provides a method for determining the key throwing orientation of the ice sheet, including the following steps:

[0049] S1: Calculate the helix H parameters at different heights of the leading edge of blade B according to the rotational speed of blade B and the axial velocity of the ice sheet, and establish the helix H;

[0050] S2: Construct the boundary surface S of the leading edge of blade B through the established multiple helixes H;

[0051] S3: Establish the boundary surface S of the leading edges of two adjacent blades B;

[0052] S4: Determine the size of the ice sheet according to the area of the engine nacelle lip and establish the geometric model of the ice sheet;

[0053] S5: Calculate the maximum axial distance that the ice sheet can advance between blades B according to the number of blades B in one circle, the rotational speed of blade B, and the velocity of the ice sheet.

[0054] S6: Offset the leading edge line of blade B axially by the maximum axial distance towards the ice blade, and then rotate this curve around the engine axis to obtain the boundary surface F at the maximum axial position.

[0055] S7: Rotate the curve at the tip of blade B around the engine axis to obtain the enveloping toroidal surface at the maximum radial position.

[0056] S8: Assemble the ice blade between two adjacent boundary surfaces S, the boundary surface F at the maximum axial position, and the enveloping toroidal surface at the maximum radial position, and at the same time make the distance between the centroid of the ice blade and the engine axis as close as possible to the radius of the blade tip.

[0057] S9: Obtain the key throwing azimuth of the ice blade according to the assembly result.

[0058] It should be noted that the distance between the centroid of the ice blade and the engine axis being as close as possible to the radius of the blade tip means that under the allowable conditions, the difference between the distance from the centroid of the ice blade to the engine axis and the radius of the blade tip is as small as possible. In the best case, the distance between the centroid of the ice blade and the engine axis is equal to the radius of the blade tip.

[0059] In some embodiments, in step S1, the helix direction of helix H is the same as the rotation direction of blade B, the radius r of helix H is the distance from the impact point to the engine axis, and the pitch of helix H is 2π×r×tan(A) = 2π×v / ω.

[0060] The helix H should be dense enough to construct the boundary surface S of the leading edge of blade B. In some embodiments, the multiple helices H include at least 10 helices H.

[0061] In some embodiments, in step S4, the ice blade dimensions are obtained according to the interpolation in FAR33.77 clause (as shown in Table 1 below), and the geometric model of the ice blade is established.

[0062] Table 1

[0063]

[0064]

[0065] According to an ice ingestion analysis method for an aeroengine provided by an embodiment of the present disclosure, it includes the method for determining the key throwing azimuth of the ice blade as described above.

[0066] The method for determining the key throwing azimuth of the ice blade in the present disclosure can determine the key azimuth of the ice blade, so as to quickly conduct tests or numerical calculations to evaluate the ice ingestion ability of the engine and the impact resistance of the blade against the ice blade, effectively saving the calculation cost and time cost. Through experimental verification, the ice blade throwing azimuth determined by this method is real and effective.

[0067] So far, the embodiments of the present disclosure have been described in detail. To avoid obscuring the concept of the present disclosure, some details well known in the art are not described. Those skilled in the art can fully understand how to implement the technical solutions disclosed herein based on the above description.

[0068] Although some specific embodiments of the present disclosure have been described in detail by way of examples, those skilled in the art should understand that the above examples are only for illustration and not for limiting the scope of the present disclosure. Those skilled in the art should understand that the above embodiments can be modified or partial technical features can be equivalently replaced without departing from the scope and spirit of the present disclosure. The scope of the present disclosure is defined by the appended claims.

Claims

1. A method for determining the critical throwing orientation of ice flakes, comprising the following steps: S1: Calculate the helix parameters at different blade heights at the leading edge of the blade according to the blade rotational speed and the axial velocity of the ice flakes, and establish a helix; S2: Construct a cutting surface at the leading edge of the blade through the established multiple helices; S3: Establish a cutting surface at the leading edges of two adjacent blades; S4: Determine the size of the ice flakes according to the area of the engine nacelle lip and establish a geometric model of the ice flakes; S5: Calculate the maximum axial distance that the ice flakes can advance between the blades according to the number of blades in one revolution, the blade rotational speed, and the ice flake velocity; S6: Axially offset the leading edge line of the blade by the maximum axial distance in the direction of ice flake movement, and then rotate this curve around the engine axis to obtain a boundary surface at the maximum axial position; S7: Rotate the curve at the blade tip around the engine axis to obtain an envelope toroid at the maximum radial position; S8: Assemble the ice flakes between two adjacent cutting surfaces, the boundary surface at the maximum axial position, and the envelope toroid at the maximum radial position, and at the same time make the distance between the centroid of the ice flakes and the engine axis as close as possible to the radius of the blade tip; S9: Obtain the critical throwing orientation of the ice flakes according to the assembly result.

2. The method for determining the key throwing orientation of borneol according to claim 1, wherein, In step S1, the helix has the same helix direction as the blade rotation direction. The blade rotates around the rotor axis at a constant speed ω, and the ice piece moves along the rotor axis direction at a constant speed v. The included angle A is the angle between the resultant velocity of any point on the blade relative to the ice piece and the tangential velocity. The radius r of the helix is the distance from the impact point to the engine axis, and the pitch of the helix is .

3. The method for determining the key throwing direction of borneol according to claim 1, wherein The multiple helices include at least 10 helices.

4. The method for determining the key throwing orientation of borneol according to claim 1, wherein, In step S4, the size of the ice flakes is obtained by interpolation according to Article FAR33.77, and a geometric model of the ice flakes is established.

5. An ice ingestion analysis method for an aeroengine, comprising the method for determining the critical throwing orientation of ice flakes according to any one of claims 1 to 4.

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