A method for drawing a function vibration spectrum of a jet airplane airborne equipment

Abstract

A jet aircraft on-board equipment function vibration spectrum drawing method, comprising the following steps: dividing and determining the installation area of the equipment on the aircraft; step 2: obtaining the low-frequency vibration value of the equipment according to the national military standard; step 3: calculating the high-frequency vibration value of the equipment according to the relevant formula of the national military standard; step 4: drawing the test vibration spectrum according to the low-frequency vibration value and the high-frequency vibration value; step 5: revising the low-frequency vibration value and the high-frequency vibration value of the equipment in the installation area; step 6: drawing the final function vibration spectrum according to the revision result. According to different installation areas, the low-frequency vibration value and the high-frequency vibration value of the equipment are revised correspondingly, so that the vibration value is close to the true value, and finally the final function vibration spectrum is drawn according to the revision result, avoiding the occurrence of over-test and under-test, making the vibration environment condition determination more reasonable, and providing scientific guidance.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of aviation, and particularly relates to a jet airplane airborne equipment function vibration spectrum drawing method. BACKGROUND

[0002] The vibration environment is an induced environment often suffered by the airborne equipment in the flight of the airplane. According to the statistical data, the faults caused by the vibration, such as the lead wire breakage and the solder point drop, account for 20% of the equipment faults. The light faults can cause the equipment faults, and the serious faults can cause the major accidents and the major economic losses. Therefore, the vibration test is indispensable in the environment test of most equipment. The vibration condition of the jet airplane airborne equipment cannot be obtained in the early development stage, and therefore the vibration condition is determined by the recommended mode in the domestic and foreign standards, which can easily lead to the same vibration condition in different installation regions, which is different from the actual situation. For example, the vibration in the regions, such as the equipment cabin, the cockpit, the tail wing, the wing and the engine cabin, should be different. According to the calculation formula in the domestic and foreign standards, it is found that the vibration value in the engine accessory region is smaller than the measured value, and the vibration value in the front fuselage is larger than the measured value. Therefore, the over test and the under test are easily caused. In view of this, it is necessary to draw the function vibration spectrum to accurately obtain the vibration environment condition, and then to more reasonably and scientifically determine the vibration environment and condition. SUMMARY

[0003] The present application aims to provide a jet airplane airborne equipment function vibration spectrum drawing method, and mainly aims to solve the above problems, so as to make the vibration environment condition determination more reasonable and scientific.

[0004] The technical scheme of the present application is as follows:

[0005] A jet airplane airborne equipment function vibration spectrum drawing method, comprising the following steps:

[0006] Step 1: dividing and determining the installation region of the equipment on the airplane

[0007] According to the vibration source and the influence region, the characteristics of the airplane and the installation characteristics of the equipment, the installation region of the equipment on the airplane can be divided into the following regions:

[0008] The front fuselage and the cockpit;

[0009] The middle fuselage and the inner 1 / 3 region of the wing;

[0010] The outer 2 / 3 region of the wing and the tail wing;

[0011] The landing gear cabin;

[0012] The region near the engine;

[0013] Step 2: obtaining the low-frequency vibration value W1 of the equipment:

[0014] Step 3: Calculate the high frequency band vibration magnitude W0 of the equipment:

[0015] The vibration formula caused by aerodynamic force is:

[0016] W A = a * b * C * q 2 (1)

[0017] The vibration formula caused by jet engine noise is:

[0018] W J = [0.48 * a * d * cos(θ) 2 / R] * [D c *(V c V r ) 3 + D f *(V f V r ) 3 ] (2)

[0020] The high frequency band vibration magnitude takes the vibration envelope caused by both aerodynamic force and jet engine noise:

[0021]

[0022] Where:

[0023] a - mass factor of the platform / equipment;

[0024] b - proportional factor between vibration magnitude and dynamic pressure (SI unit);

[0025] d - afterburner factor;

[0026] R - vector distance between the equipment's center of gravity and the center of the engine's exhaust, m;

[0027] θ - the angle between the R vector and the engine exhaust vector (backward along the engine exhaust centerline), in degrees;

[0028] Dc - engine core exhaust diameter, m;

[0029] Df - engine fan exhaust diameter, m;

[0030] Vr - reference exhaust velocity, m / s;

[0031] c - Mach number correction;

[0032] Vc - engine core exhaust velocity (without afterburner), m / s;

[0033] Vf — engine fan exhaust velocity (without afterburner), m / s;

[0034] q — flight dynamic pressure, KN / m2;

[0035] — the sum of the vibration values caused by the noise of each engine on the aircraft;

[0036] W A — the vibration value caused by aerodynamic force;

[0037] W J — the vibration value caused by jet engine noise;

[0038] Step 4: According to the low-frequency vibration value W1 and the high-frequency vibration value W0, draw the test vibration spectrum;

[0039] Step 5: According to the distance between the equipment and the engine exhaust, revise the low-frequency vibration value W1 of the equipment in the installation area;

[0040] The high-frequency vibration value W0 of the airborne equipment installed in the front fuselage and the cabin, the middle fuselage and the inner 1 / 3 area of the wing is calculated according to formula (1) - formula (3), and is not revised;

[0041] The high-frequency vibration value W0 of the airborne equipment installed in the outer 2 / 3 area of the wing, the tail, the landing gear compartment and the engine area is revised;

[0042] Step 6: Draw the final functional vibration spectrum according to the revision result.

[0043] Further, in step 5: The formula for revising the low-frequency vibration value W1 of the equipment in the installation area is as follows:

[0044] N = 3 * Log 10 (R) (4)

[0045] W1 * = W1 / 10 (N / 10) (5)

[0046] N — attenuation coefficient, dB;

[0047] R — the vector distance between the center of gravity of the equipment and the engine exhaust, m;

[0048] W1 * — the revised value of the low-frequency vibration value.

[0049] Further, in step 5: The formula for revising the high-frequency vibration value W0 of the airborne equipment installed in the outer 2 / 3 area of the wing, the tail, the landing gear compartment and the engine area is as follows:

[0050]

[0051] wherein, - the high-frequency band envelope vibration quantity revision value.

[0052] The present application has the following beneficial effects:

[0053] The present application obtains the low-frequency band vibration quantity value of the equipment according to GJB150.16A and calculates the high-frequency band vibration quantity value according to the characteristics of the vibration measured data of similar models and the specific installation area of the equipment, thereby drawing the test vibration spectrum, revising the low-frequency band vibration quantity value and the high-frequency band vibration quantity value of the equipment according to different installation areas, making the vibration quantity value close to the true value, and finally drawing the final functional vibration spectrum according to the revision result, avoiding the occurrence of over-test and under-test, making the vibration environment condition determination more reasonable, and providing scientific guidance. BRIEF DESCRIPTION OF DRAWINGS

[0054] Figure 1 is the test vibration spectrum of the equipment A;

[0055] Figure 2 is the vibration spectrum drawn according to the method of the present application; DETAILED DESCRIPTION

[0056] The present application can be further described by the following implementation cases, however, the scope of the present application is not limited to the following examples.

[0057] Example: a method for drawing the functional vibration spectrum of an airborne equipment of a jet aircraft, comprising the following steps:

[0058] Step 1: dividing and determining the installation area of the equipment on the aircraft

[0059] According to the characteristics of the vibration source and its influence area, the aircraft and the installation characteristics of the equipment, the installation area of the equipment on the aircraft can be divided into the following areas:

[0060] front fuselage and cockpit;

[0061] cockpit instrument panel;

[0062] middle fuselage and inner 1 / 3 area of the wing;

[0063] outer 2 / 3 area of the wing and tail;

[0064] landing gear compartment;

[0065] engine vicinity area;

[0066] engine;

[0067] external hanging;

[0068] Among them: because the category of vibration environment of airborne equipment installed on the engine and external hanging is special, the determination method of vibration value and functional vibration spectrum have their respective methods, in addition, the one installed on the cockpit instrument panel also has its special consideration, so the method of the application is not applicable to the above three cases.

[0069] Step 2: Obtain the low-frequency vibration value W1 of the equipment according to the national military standard:

[0070] Step 3: Calculate the high-frequency vibration value W0 of the equipment:

[0071] The vibration formula caused by aerodynamic force is:

[0072] W A =a*b*C*q 2 (1)

[0073] The vibration formula caused by jet engine noise is:

[0074] W J =[0.48*a*d*cos(θ) 2 / R]*[D c *(V c V r ) 3 +D f *(V f V r ) 3 ] (2)

[0075] The high-frequency vibration value is the vibration envelope formula caused by aerodynamic force and jet engine noise:

[0076]

[0077] Among them:

[0078] a-the mass factor of the platform / equipment;

[0079] b-the proportional factor between vibration value and dynamic pressure (SI unit);

[0080] d-the afterburner factor;

[0081] R-the vector distance between the center of gravity of the equipment and the center of the engine tail nozzle, m;

[0082] θ-the angle between the R vector and the engine tail nozzle vector (backward along the engine tail nozzle center line), in degrees;

[0083] Dc-the engine core exhaust diameter, m;

[0084] Df - engine fan exit diameter, m;

[0085] Vr - reference exhaust velocity, m / s;

[0086] c - Mach number correction;

[0087] Vc - engine core exit velocity (without afterburner), m / s;

[0088] Vf - engine fan exit velocity (without afterburner), m / s;

[0089] q - flight dynamic pressure, KN / m2;

[0090] - the sum of vibration values caused by engine noise on the aircraft;

[0091] W A - vibration value caused by aerodynamic force;

[0092] W J - vibration value caused by jet engine noise;

[0093] Step 4: According to the low-frequency vibration value W1 and the high-frequency vibration value W0, draw the test vibration spectrum;

[0094] Step 5: According to the distance between the equipment and the engine exhaust, revise the low-frequency vibration value W1 of the equipment in the installation area;

[0095] The high-frequency vibration value W0 of the airborne equipment installed in the front fuselage and the cabin, the middle fuselage and the inner 1 / 3 area of the wing is calculated according to formula (1)-formula (3) without revision;

[0096] The high-frequency vibration value W0 of the airborne equipment installed in the outer 2 / 3 area of the wing, the tail, the landing gear compartment and the engine area is revised;

[0097] Step 6: Draw the final functional vibration spectrum according to the revision results.

[0098] Further, in step 5: The formula for revising the low-frequency vibration value W1 of the equipment in the installation area is as follows:

[0099] N = 3 * Log 10 (R) (4)

[0100] W1 * = W1 / 10 (N / 10) (5)

[0101] N - attenuation coefficient, dB;

[0102] R - the vector distance between the center of gravity of the equipment and the center of the engine exhaust, m;

[0103] W1 * - the revised value of the low-frequency vibration quantity.

[0104] Further, in step 5: the high-frequency vibration quantity value W0 of the airborne equipment installed in the outer 2 / 3 area of the wing, the tail, the landing gear compartment and the area near the engine is revised as follows:

[0105]

[0106] wherein, - the revised value of the high-frequency vibration quantity.

[0107] Specific embodiment: taking equipment A on a certain type of aircraft as an example, the maximum dynamic pressure allowed by the aircraft is q = 26.5 KN / m 2 , R = 2.955 m, 70° < θ < 180°, the aircraft has two turbojet engines without afterburner in the rear fuselage, the core engine of which has D c = 0.38 m, V c = 204.6 m / s; the fan engine has D f = 0.53 m, V f = 237.5 m / s, according to the characteristics of the aircraft and the installation position of equipment A, the mass factor of the platform / equipment: a = 1; the proportion factor between the vibration quantity value and the dynamic pressure: b = 6.11 x 10 -5 ; the afterburner factor d = 1; the Mach number revision c = 1; the function vibration spectrum drawing method, including the following steps:

[0108] Step 1: According to the installation position of equipment A, divide and determine that equipment A belongs to the area near the engine;

[0109] Step 2: Obtain the low-frequency vibration quantity value W1 of equipment A according to the national military standard, as shown in the following formula: Figure 1 The low-frequency range of equipment A is (15 HZ-f), W1 = 0.04 g 2 / HZ,

[0110] Step 3: Calculate the high-frequency vibration quantity value W0 of equipment A:

[0111] According to formula (1), the vibration caused by aerodynamic force is calculated:

[0112] W A = a * b * c * q 2

[0113] = 1 * 6.11 x 10 -5 * 1 * 26.5 2

[0114] = 0.043 g 2 / Hz

[0115] The jet engine noise induced vibration is calculated according to formula (2):

[0116] W J = [0.48 * a * d * cos (θ) 2 / R] * [D c * (V c / V r ) 3 + D f * (V f / V r ) 3 ]

[0117] = [0.48 * 1 * 1 * cos (70°) 2 / 2.955] * [0.38 * (204.6 / 564) 3 + 0.54 * (237.5 / 564) 3]

[0118] = 0.0011 g 2 / Hz

[0119] Step 4: According to the low frequency vibration value W1 and the high frequency vibration value W0, the test vibration spectrum is drawn as shown in Figure 1 ;

[0120] Step 5: The low frequency vibration value W1 and the high frequency vibration value W0 of the equipment are revised; because the equipment A is installed in the engine accessory area, the low frequency vibration value of the equipment A is revised for attenuation:

[0121] N = 3 * Log 10 (2.955) = 1.43 dB

[0122] W1 * = W1 / 10 (N / 10) = 0.04 / 10 (1.43 / 10) = 0.0288

[0123] The high frequency range of the equipment A is (300 HZ-1000 HZ), and considering that the installation area is close to the engine tail nozzle, the jet noise induced vibration cannot be reduced, and the high frequency vibration value is revised:

[0124]

[0125] Step 6: According to the revision result, the function vibration spectrum of the equipment A is drawn, see Figure 2 .

[0126] The foregoing merely illustrates the principles of the application and application of its leading features. This application is not limited to the illustrative embodiments shown and described herein. Rather, this application is capable of operating within a further range of conditions and environments than those specifically described herein, and further modifications can be made without departing from the spirit or scope of the application. Accordingly, the description is to be construed as illustrative only and not restrictive of the broad disclosure or application of the application. The specification and drawings are, accordingly, to be regarded simply as illustrative and with the scope of the application being measured by the appended claims, and not with the specification. No admission is made that any reference constitutes prior art. It is my intent, therefore, to be limited only as appears in the following claims.

[0127] Furthermore, it should be understood that although the description above relates to embodiments, not every embodiment according to the description contains each and every feature or combination of features. Some embodiments can be comprised of some features of the description while others can be devoid of certain features. Therefore, features or combinations of features of the description should be considered as exemplary and not mandatory unless otherwise indicated by the patentable subject matter.

Claims

1. A method of jet-borne device functional vibration spectrum mapping, the method comprising: Comprising the following steps: ​ Step 1: Divide and determine the installation area of equipment on the aircraft According to the vibration source and its influence area, the characteristics of the aircraft and the installation characteristics of the equipment, the installation area of the equipment on the aircraft is divided into the following areas: Front fuselage and cockpit; Mid-fuselage and 1 / 3 inboard area of wing; 2 / 3 outboard area of wing, tail; Landing gear compartment; Engine vicinity area; Step 2: Obtain the low-frequency vibration value W1 of the equipment: Step 3: Calculate the high-frequency vibration value W0 of the equipment: The vibration formula caused by aerodynamic force is: W A = a * b * C * q 2 (1) The vibration formula caused by jet engine noise is: W J = [0.48 * a * d * cos(θ) 2 / R] * [D c *(V c / V r ) 3 + D f *(V f / V r ) 3 ] (2) The high-frequency vibration value is the envelope of the vibration caused by aerodynamic force and jet engine noise: Where: a - mass factor of platform / equipment; b - proportional factor between vibration value and dynamic pressure, SI unit; d - afterburner factor; R - vector distance between the center of gravity of the equipment and the center of the engine exhaust, m; θ - the angle between the R vector and the engine exhaust vector, measured along the engine exhaust center line backward, in degrees; Dc - engine core exhaust diameter, m; Df - engine fan exhaust diameter, m; Vr - reference exhaust velocity, m / s; c - Mach number correction; Vc - engine core exhaust velocity, measured without afterburner, m / s; Vf - engine fan exhaust velocity, measured without afterburner, m / s; q - flight dynamic pressure, KN / m2; - the sum of the vibration values caused by the noise of each engine on the aircraft; W A — the magnitude of the vibration caused by aerodynamic forces; W J - the magnitude of the vibration caused by the jet engine noise; Step 4: Draw the test vibration spectrum according to the low-frequency vibration value W1 and the high-frequency vibration value W0; Step 5: Revise the low-frequency vibration value W1 of the equipment in the installation area according to the distance of the equipment from the engine exhaust; The high-frequency vibration value W0 of the airborne equipment installed in the front fuselage and cockpit, mid-fuselage and 1 / 3 inboard area of wing is calculated according to formula (1) - formula (3) without revision; The high-frequency vibration value W0 of the airborne equipment installed in the 2 / 3 outboard area of wing, tail, landing gear compartment and engine vicinity area is revised; Step 6: Draw the final functional vibration spectrum according to the revision results.

2. The method of claim 1, wherein, In step 5: The formula for revising the low-frequency vibration value W1 of the equipment in the installation area is as follows: N = 3 * Log 10 (R) (4) W1 * = W1 / 10 (N / 10) (5) N - attenuation coefficient, dB; R - vector distance between the center of gravity of the equipment and the center of the engine exhaust, m; W1 * — low frequency band vibration amount revision value.

3. The method of claim 1, wherein: In step 5: The formula for revising the high-frequency vibration value W0 of the airborne equipment installed in the 2 / 3 outboard area of wing, tail, landing gear compartment and engine vicinity area is as follows: wherein, - high frequency band vibration amount revision value.

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