Method for calculating particle clogging probability of flow element

Abstract

This invention relates to a method for calculating the probability of particulate blockage in a flow element. The method involves allowing fuel containing particulate matter to flow at a velocity V through the flow element from an upstream cavity to a downstream cavity for a time t. The method measures the fuel volume W1 and the particulate concentration R1 in the downstream cavity after the fuel has flowed for t time. W1 = W0 + V * t * π * D 2 / 4, where D is the diameter of the throat cross section or the hydraulic diameter of the throat of the flow element; Step 3, obtain the number of particles P contained in the fuel passing through the flow element by the formula P = W1*R1 - W0*R0; Step 4, obtain the throughput A by the formula: A = P*L / V, where L is the length of the throat of the flow element; Step 5, obtain the blockage probability E(A) by the formula: where i > 0 and is a natural number; m is the minimum blockage particle agglomeration number, m = [D / d] + 1, m is a dimensionless quantity, and d is the particle size or equivalent diameter.

Description

Technical Field

[0001] This invention relates to the field of cleanliness control and reliability technology of aero-engine fuel control systems, and to estimation of failure probability of flow components and estimation of anti-contamination design, specifically a method for calculating the probability of particulate blockage of flow components. Background Technology

[0002] The fuel control unit is a key part of the fuel supply system of an aircraft engine. It supplies and delivers fuel to the engine according to the commands of the engine electronic controller. The fuel system contains a large number of precision-fitted parts, electrical accessories, and a large number of flow components. These components are very sensitive to the cleanliness of the fuel. Particulate contaminants in the fuel can cause jamming and blockage, and in severe cases, can lead to engine failure and shutdown. To ensure the normal operation of the entire fuel system, it is necessary to strictly control the cleanliness of the fuel.

[0003] The main current measure is to filter fuel through oil filters to isolate particulate contaminants in the fuel. However, because particulate contaminants have a certain degree of stickiness, they have a certain probability of agglomerating into large particles under the action of static electricity, van der Waals forces, etc., causing blockage failures. Therefore, in the design process of flow elements, it is necessary to further evaluate the relevant blockage probability and improve the anti-pollution performance. However, there is currently a lack of relevant quantitative evaluation methods and a lack of benchmarks for the anti-pollution design of flow elements. Summary of the Invention

[0004] The purpose of this invention is to obtain the probability of blockage of flow elements, reduce the cost of long-term testing, and make the results applicable to screening and evaluating the merits of anti-contamination design schemes.

[0005] The technical solution of this invention is:

[0006] A method for calculating the probability of particulate matter blockage in a flow element is provided, the method comprising the following steps:

[0007] Step 1: Construct a throttling test system, which includes an upstream cavity, a flow element, and a downstream cavity; the upstream cavity contains fuel containing particulate matter, and the fuel can flow to the downstream cavity through the flow element;

[0008] The initial fuel volume W0 and the initial particulate matter concentration R0 in the downstream cavity are obtained.

[0009] Step 2: Allow the fuel containing particulate matter to flow from the upstream cavity to the downstream cavity through the flow element at a flow rate V for time t; measure the fuel volume W1 and the particulate concentration R1 in the downstream cavity after the fuel has flowed for time t; W1 = W0 + V * t * π * D 2 / 4, where D is the diameter of the throat circular section of the flow element or the hydraulic diameter of the throat;

[0010] Step 3: Obtain the number of particulate matter P contained in the fuel passing through the flow element using the formula P = W1 * R1 - W0 * R0;

[0011] Step 4: Obtain the throughput A using the formula: A = P * L / V, where L is the throat length of the flow element;

[0012] Step 5: Obtain the congestion probability E(A) using the formula:

[0013] Where: i > 0 and is a natural number; m is the minimum number of clogged particles, m = [D / d] + 1, m is a dimensionless quantity, and d is the particle size or equivalent diameter. For ease of explanation, m can be understood as the integer multiple of the throat cross-section diameter or throat hydraulic diameter of the flow element relative to the particle space size, plus 1.

[0014] Furthermore, if the blockage probability is greater than 10 -5 It is recommended to improve the design of the circulating components.

[0015] Furthermore, the particle size or maximum spatial size of the particulate matter ranges from 50 μm to 1 mm.

[0016] Furthermore, the flow element is a throttle valve.

[0017] Furthermore, the flow element is an element with a variable cross-section flow path.

[0018] Furthermore, the particulate matter can be metallic or non-metallic particles.

[0019] Furthermore, the particulate matter can be organic or inorganic.

[0020] Furthermore, the aggregation of the particulate matter blockage can be caused by electrostatics, van der Waals forces, or adhesion.

[0021] The advantages of this invention are: it is an original method for assessing the probability of blockage in flow elements. Before this method, to prevent blockage, it was often necessary to increase the flow area of ​​the flow element, but all these design improvements were qualitative, without quantitative results, and there was no unified standard to measure the probability of blockage in different configurations, thus failing to provide a method for optimal solution selection. Physical blockage testing is time-consuming and labor-intensive, which is not conducive to rapid design iteration.

[0022] By adopting this method, the necessary calculation data can be obtained using simple experimental methods and professional measuring equipment, or even by directly using simulation methods to obtain the necessary data, which can then be used to start rapid evaluation, greatly improving work efficiency and significantly reducing the manpower and experimental costs of physical blockage testing. Attached Figure Description

[0023] Figure 1 A schematic diagram showing the distribution of particulate pollutants upstream and downstream of this type of throttling nozzle after the filter screen has been removed.

[0024] Wherein: 1 - throat of the flow element. Detailed Implementation

[0025] The disclosed examples will be described more fully with reference to the accompanying drawings, in which some (but not all) of the disclosed examples are shown. In fact, many different examples may be described, and these examples should not be construed as limited to those set forth herein. Rather, these examples are described so that this disclosure will be thorough and complete, and will fully convey the scope of this disclosure to those skilled in the art.

[0026] A method for calculating the probability of particulate matter blockage in a flow element is provided, the method comprising the following steps:

[0027] Step 1: Construct a throttling test system, which includes an upstream cavity, a flow element, and a downstream cavity; the upstream cavity contains fuel containing particulate matter, and the fuel can flow to the downstream cavity through the flow element;

[0028] The initial fuel volume W0 and the initial particulate matter concentration R0 in the downstream cavity are obtained.

[0029] Step 2: Allow the fuel containing particulate matter to flow from the upstream cavity to the downstream cavity through the flow element at a flow rate V for time t; measure the fuel volume W1 and the particulate concentration R1 in the downstream cavity after the fuel has flowed for time t; W1 = W0 + V * t * π * D 2 / 4, where D is the diameter of the throat circular section of the flow element or the hydraulic diameter of the throat;

[0030] Step 3: Obtain the number of particulate matter P contained in the fuel passing through the flow element using the formula P = W1 * R1 - W0 * R0;

[0031] Step 4: Obtain the throughput A using the formula: A = P * L / V, where L is the throat length of the flow element;

[0032] Step 5: Obtain the congestion probability E(A) using the formula:

[0033] Where: i > 0 and is a natural number; m is the minimum number of clogged particles, m = [D / d] + 1, m is a dimensionless quantity, and d is the particle size or equivalent diameter. For ease of explanation, m can be understood as the integer multiple of the throat cross-section diameter or throat hydraulic diameter of the flow element relative to the particle space size, plus 1.

[0034] If the blockage probability is greater than 10 -5 .

[0035] The particle size or maximum spatial size of the particles ranges from 50 μm to 1 mm.

[0036] The flow element is a throttle valve.

[0037] The flow element is an element with a variable cross-section flow path.

[0038] The particulate matter is non-metallic.

[0039] The particulate matter can be organic or inorganic.

[0040] The aggregation of the particulate matter blockage occurs through electrostatics, van der Waals forces, or adhesion.

[0041] Descriptions of various advantageous arrangements have been shown for illustrative and descriptive purposes, but such descriptions are not intended to be exclusive or limited to the disclosed forms. Many modifications and variations will be apparent to those skilled in the art. Furthermore, different advantageous examples may describe different advantages compared to other advantageous examples. One or more examples have been selected and described in order to best illustrate the principles and practical application of the examples, and to enable those skilled in the art to understand that this disclosure contains various examples with various modifications suitable for the particular intended use.

Claims

1. A method for calculating the probability of particulate matter blockage in a flow element, characterized in that, The method includes the following steps: Step 1: Construct a throttling test system, which includes an upstream cavity, a flow element, and a downstream cavity; the upstream cavity contains fuel containing particulate matter, and the fuel can flow to the downstream cavity through the flow element; The initial fuel volume W0 and the initial particulate matter concentration R0 in the downstream cavity are obtained. Step 2: Allow the fuel containing particulate matter to flow from the upstream cavity to the downstream cavity through the flow element at a flow rate V for time t; measure the fuel volume W1 and the particulate concentration R1 in the downstream cavity after the fuel has flowed for time t; W1 = W0 + V * t * π * D 2 / 4, where D is the diameter of the throat circular section of the flow element or the hydraulic diameter of the throat; Step 3: Obtain the number of particulate matter P contained in the fuel passing through the flow element using the formula P=W1*R1-W0*R0; Step 4: Obtain the throughput A using the formula: A = P * L / V, where L is the throat length of the flow element; Step 5: Obtain the congestion probability using the formula. The formula is: ， Where: i > 0 and is a natural number; m is the minimum number of clogged particles, m = [D / d] + 1, m is a dimensionless quantity, d is the particle size or equivalent diameter, and m means the ratio of the diameter of the throat circular section of the flow element or the hydraulic diameter of the throat to the spatial size of the particles, rounded down and then increased by 1.

2. The method for calculating the probability of particulate matter blockage in a flow element as described in claim 1, characterized in that: The particle size or equivalent diameter of the particulate matter ranges from 50 μm to 1 mm.

3. The method for calculating the probability of particulate matter blockage in a flow element as described in claim 1, characterized in that: The flow element is a throttle valve.

4. The method for calculating the probability of particulate matter blockage in a flow element as described in claim 1, characterized in that: The flow element is an element with a variable cross-section flow path.

5. The method for calculating the probability of particulate matter blockage in a flow element as described in claim 1, characterized in that: The particulate matter can be metallic or non-metallic.

6. The method for calculating the probability of particulate matter blockage in a flow element as described in claim 1, characterized in that: The particulate matter can be organic or inorganic.

7. The method for calculating the probability of particulate matter blockage in a flow element as described in claim 1, characterized in that: The aggregation of the particulate matter blockage occurs through electrostatics, van der Waals forces, or adhesion.

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