A rotor oil accumulation test platform and method

Abstract

The present invention discloses a rotor oil accumulation test platform and method, which relate to the fields of vibration testing and high-speed camera testing. The rotor oil accumulation test platform includes: a unified shaft for driving the entire device to rotate; a suspended fuel tank for placing oil droplets; a bearing housing to make the rotation more stable; four stabilizing members for stabilizing the device; and a device plate for connecting components. The present invention also provides a method based on the rotor oil accumulation test platform, which accurately monitors and controls the test process, making the rotor oil accumulation test platform have the advantages of combining theory with experiment, being portable, easy to operate, and having accurate test results.

Description

Technical Field

[0001] The invention relates to the field of vibration testing and high-speed camera testing, and in particular to a rotor oil accumulation test platform and a rotor oil accumulation test method. Background Art

[0002] High-speed light structure is the development trend of high-speed rotating machinery in recent years. While it improves the performance of the rotor, it may also cause the aircraft engine to be unstable or even instability. Therefore, the dynamic stability of the aircraft engine system is an important research topic in modern rotor dynamics.

[0003] The instability of aircraft engines filled with viscous incompressible fluids such as oil accumulation is a common problem in rotating machinery, which causes the amplitude of disturbances to grow exponentially. Due to the interaction between the fluid and the solid rotor, a fluid-solid coupling phenomenon is formed, and the rotor filled with fluid will become unstable within a certain speed range. Considering the coupling effect of friction and gyroscopic force, an unstable region is found. The present invention adopts a bifurcation method to theoretically analyze the mechanism of instability of aircraft engines caused by fluids, and at the same time builds a tester to verify the stability region, thereby studying the influence of aircraft engine dynamic parameters on stability and revealing the instability mechanism of aircraft engines.

[0004] Rotating machinery has been used for a long time. In recent decades, due to the promotion and needs of the industrial sector, especially the aviation and power sectors, the study of rotor dynamics has become an important branch in the field of vibration. As the design of rotors develops towards large-scale, high-speed, heavy-load and flexible, many serious instability phenomena have been brought about, which has become a major problem that troubles engineers. Therefore, the study of the operating stability of the rotor system has become a major task in rotor dynamics. There are many factors that cause rotor instability, mainly oil film force, material and structural internal resistance, liquid-filled rotors and friction. The fundamental reason for instability is that the rotor is subjected to a tangential force when it is disturbed. When it is large enough, it can overcome the effect of external damping and cause the amplified vortex of the shaft, which brings serious consequences. Summary of the invention

[0005] The purpose of the present invention is to overcome the deficiencies in the prior art and to provide a rotor oil accumulation test platform and method that can accurately monitor and control the test process.

[0006] In order to achieve the above functions, the present invention designs a rotor oil accumulation test platform for analyzing the stability of rotor oil accumulation, including: a steel frame, a device plate, an oil tank, a bearing, a bearing seat, a rotor, and a stabilizing member;

[0007] The steel frame is composed of a rectangular upper bottom plate and a lower bottom plate of the same size, and four columns of the same size. The two ends of the four columns are fixedly connected to the four corners of the upper bottom plate and the lower bottom plate respectively. The upper bottom plate and the lower bottom plate are parallel and opposite to each other.

[0008] The stabilizing members are used to install the device plate between the upper bottom plate and the lower bottom plate of the steel frame. The number of the stabilizing members is the same as the number of the columns of the steel frame, and the sizes and shapes of the stabilizing members are the same. One end of the stabilizing member is provided with an opening, and the shape of the opening corresponds to the cross-section of the column of the steel frame, and is used for socket-fixing and installing on the column of the steel frame. The other end of the stabilizing member is provided with a screw hole, which is used for fixedly installing the device plate. When each stabilizing member is respectively installed on the column of the steel frame, they are located on the same horizontal plane;

[0009] The device plate is a rectangular plate with the same size as the upper bottom plate and the lower bottom plate of the steel frame. The center position of the device plate is provided with a preset number of screw holes, which are used for fixedly installing the bearing seat. The four corners of the device plate are provided with openings, and the shape of each opening corresponds to the cross-section of the column of the steel frame. Each column of the steel frame respectively passes through the openings at the four corners of the device plate, so that the device plate is socket-fixed between the upper bottom plate and the lower bottom plate of the steel frame; the device plate is provided with screw holes, and the positions of the screw holes respectively correspond to the screw holes on each stabilizing member, so that the device plate is fixed on each stabilizing member between the steel frames by screws;

[0010] The bearing seat is used to connect the bearing. Its base is a rectangular structure with screw holes at the four corners. The screw holes at the base of the bearing seat correspond to the screw holes of the device plate, and the bearing seat is fixedly connected to the device plate by screws; the bearing is connected to the bearing seat and is connected to the oil tank through the rotor. When the rotor is driven by the motor, the oil tank rotates under the drive of the rotor.

[0011] The present invention also designs a method based on the above rotor oil accumulation test platform, and performs the following steps S1-step S5 to complete the rotor oil accumulation stability analysis by constructing a rotor oil accumulation fault model:

[0012] Step S1: Construct a rotor model. According to the dynamic parameters of the rotor, based on the NS equation, establish a fluid-structure interaction model, and theoretically establish a rotor oil accumulation fault model;

[0013] Step S2: Keep the oil tank stationary and pour a certain amount of water into the oil tank;

[0014] Step S3: The motor drives the rotor to rotate, and its speed is increased from 0 to a preset stable state. Record the rotor speed in the stable state, and then turn off the motor;

[0015] Step S4: Based on the rotor speed in the stable state and the rotor oil accumulation fault model, analyze the rotor stability;

[0016] Step S5: Repeat steps S2-step S4. If the analysis results of the rotor stability are the same twice, then pour a certain amount of oil into the oil tank, and perform steps S3-step S4 to complete the rotor oil accumulation stability analysis. Otherwise, repeat steps S2-step S4 until the analysis result of the rotor stability the same as that in step S4 is obtained.

[0017] Beneficial effects: Compared with the prior art, the advantages of the present invention include:

[0018] The present invention designs a rotor oil accumulation test platform and method, which accurately monitors and controls the test process, making the rotor oil accumulation test platform have the advantages of combining theory with experiment, being portable, easy to operate, and having accurate test results. Brief Description of the Drawings

[0019] Figure 1 is a schematic diagram of the rotor oil accumulation test platform provided according to an embodiment of the present invention;

[0020] Figure 2 is a schematic diagram of the bearing seat in the rotor oil accumulation test platform provided according to an embodiment of the present invention;

[0021] Figure 3 is a schematic diagram of the bearing in the rotor oil accumulation test platform provided according to an embodiment of the present invention;

[0022] Figure 4 is a schematic diagram of the rotor oil accumulation test method provided according to an embodiment of the present invention.

[0023] Wherein: 1, steel frame; 2, device plate; 3, fuel tank; 4, bearing; 5, bearing seat; 6, stabilizing member; Detailed Embodiments

[0024] The present invention will be further described below with reference to the drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention and cannot be used to limit the protection scope of the present invention.

[0025] Refer to Figures 1 - 4 As shown, a rotor oil accumulation test platform provided by an embodiment of the present invention is used to analyze the stability of rotor oil accumulation, and includes: a steel frame 1, a device plate 2, a fuel tank 3, a bearing 4, a bearing seat 5, a rotor, and a stabilizing member 6;

[0026] The steel frame 1 is composed of a rectangular upper bottom plate, a lower bottom plate with the same size, and four columns with the same size. The two ends of the four columns are respectively fixedly connected to the four corners of the upper bottom plate and the lower bottom plate, and the upper bottom plate and the lower bottom plate are parallel and opposite to each other;

[0027] The stabilizing member 6 is used to install the device plate 2 between the upper bottom plate and the lower bottom plate of the steel frame 1. The number of the stabilizing members 6 is the same as the number of the columns of the steel frame 1, and the sizes and shapes of the stabilizing members 6 are the same. One end of the stabilizing member 6 is provided with an opening, and the shape of the opening corresponds to the cross-section of the column of the steel frame 1 for socketing and fixedly installing on the column of the steel frame 1. The other end of the stabilizing member 6 has a threaded hole for fixedly installing the device plate 2. When the stabilizing members 6 are respectively installed on the columns of the steel frame 1, they are located on the same horizontal plane;

[0028] The device plate 2 is a rectangular plate with the same size as the upper bottom plate and the lower bottom plate of the steel frame 1. The center position of the device plate 2 has a preset number of screw holes for fixedly installing the bearing seat 5. The four corners of the device plate 2 are provided with openings, and the shape of each opening corresponds to the cross-section of the upright column of the steel frame 1. Each upright column of the steel frame 1 passes through the openings at the four corners of the device plate 2, so that the device plate 2 is sleeved and fixed between the upper bottom plate and the lower bottom plate of the steel frame 1; The device plate 2 is provided with screw holes, and the positions of the screw holes respectively correspond to the screw holes on each stabilizing member 6, so that the device plate 2 is fixed on each stabilizing member 6 between the steel frames 1 by screws;

[0029] Refer to Figure 2 , the bearing seat 5 is used to connect the bearing 4, and its base is a rectangular structure with screw holes at the four corners. The screw holes at the base of the bearing seat 5 correspond to the screw holes of the device plate 2, and the bearing seat 5 is fixedly connected to the device plate 2 by screws; Refer to Figure 3 , the bearing 4 is connected to the bearing seat 5 and is connected to the fuel tank 3 through the rotor. When the rotor is driven by the motor, the fuel tank 3 rotates under the drive of the rotor.

[0030] Refer to Figure 4 , the embodiment of the present invention also provides a rotor oil accumulation test method. Based on the above-mentioned rotor oil accumulation test platform, the following steps S1 - step S5 are executed to complete the rotor oil accumulation stability analysis by constructing a rotor oil accumulation fault model:

[0031] Step S1: Construct a rotor model. According to the dynamic parameters of the rotor, based on the NS equation, establish a fluid-structure interaction model, and theoretically establish a rotor oil accumulation fault model;

[0032] The method for theoretically establishing the rotor oil accumulation fault model in step S1 is as follows:

[0033] Step S11: Assume that the whirling shape is an exponential shape, then the rotor model in the cylindrical coordinate system fixed to the rotor is as follows:

[0034]

[0035]

[0036] In the formula, r and φ are respectively the radius and rotation angle of the rotor, u and v are respectively the rotational speeds of the rotor in the radius r and rotation angle φ directions at time t, p is the pressure, ρ is the liquid density, ε1 and ε2 are perturbation parameters, Ω is the rotor angular velocity, λ = α + iω, α is the stability parameter, and ω is the whirling frequency;

[0037] For an incompressible fluid, the continuity equation is as follows:

[0038]

[0039] For a non-viscous fluid, the boundary conditions are as follows:

[0040]

[0041] In the formula, a represents the inner wall of the rotor, and R is the free surface function, whose expression is R = b + η1(φ1, t)·ε1 + η2(φ2, t)·ε2. When R = b, b is the position of the undisturbed free surface. The following formula is derived:

[0042]

[0043] Step S12: The Euler equations (1a)-(1b) are both non-linear and cannot give a complete analytical expression by analytical means. Therefore, the perturbation method is adopted. Using the perturbation parameters ε1 and ε2, the rotor model is linearized, and the higher-order terms are ignored. Then, the following formula is obtained:

[0044]

[0045] Substitute Equation (5) into the rotor model (1a)-(1b) to obtain the zero-order solutions u0, υ0, and p0 corresponding to the undisturbed rotor as follows:

[0046]

[0047] After perturbation, the momentum equations (1a)-(1b) that the first-order solutions need to satisfy are as follows:

[0048]

[0049]

[0050]

[0051]

[0052] The corresponding continuity equation is as follows:

[0053]

[0054] The corresponding boundary conditions are as follows:

[0055] u1(a) = 0; u2(a) = 0 (9a)

[0056] p1(b) = -ρΩ 2 bη1; p2(b) = -ρΩ 2 bη2 (9b)

[0057]

[0058] In the formula, η1 and η2 are the response functions of the perturbation;

[0059] Step S13: The rotor wall pressure expression is as follows:

[0060]

[0061] In the formula, p(a) represents the pressure on the inner wall a of the rotor, φ is the rotation angle of the rotor, σ and γ are a pair of auxiliary quantities, and i is a complex number, specifically as follows:

[0062] γ = λ - iΩ; σ = λ + iΩ (11)

[0063] Γ (Γ is the capital gamma) is specifically as follows:

[0064]

[0065] Replace λ, ε1, ε2, γ, and Γ with iw, ε, -iε, iσ, and γ respectively, where Γ is the filling ratio, w is the dimensionless eigenvalue, and ε1, ε2 are perturbation parameters;

[0066] Step S14: When the fluid is inviscid, the shear stress is not considered, and the resultant force on the inner wall of the rotor in the rotating coordinate system is obtained by integrating the pressure on the inner wall of the rotor:

[0067]

[0068]

[0069] where a is the radius of the rotor wall and L is the length of the rotor;

[0070] Equations (13a)-(13b) give the resultant forces in the x and y directions. That is, in the rotating coordinate system, to establish the equilibrium dynamic equation, the resultant forces in the fixed reference frame (in the stationary coordinate system, i.e., the inertial coordinate system) X and Y are required. By rotating F x 、F y , the resultant force on the inner wall of the rotor in the stationary coordinate system can be obtained as follows:

[0071] F X = F x cos(Ωt) - F y sin(Ωt) (14a)

[0072] F Y = F x sin(Ωt) + F y cos(Ωt) (14b)

[0073] Combining equations (10)-(14), the following equation is finally obtained:

[0074]

[0075] Wherein:

[0076]

[0077]

[0078] In the formula, m1 is the mass of the liquid required to completely fill the cavity of the fuel tank 3, and m1 = ρπa 2 L (17);

[0079] Step S15: Establish the following equilibrium equation:

[0080] [M]{ε}+[C]{ε}+[S]{ε}=-[F]{ε} (18)

[0081]

[0082] In the formula, m r is the mass of the empty rotor, c X , c Y are dimensionless external damping coefficients, and k X , k Y are the rigidities in the main directions;

[0083] According to the above formula, a homogeneous equation set is obtained, and its non-singular solution exists only when the determinant of the homogeneous equation set is equal to 0. According to the determinant condition, the characteristic equation is obtained as follows:

[0084] b8w 8 +b7w 7 +b6w 6 +b5w 5 +b4w 4 +b3w 3 +b2w 2 +b1w 1 +b0=0 (20)

[0085] Wherein:

[0086]

[0087] In the formula, μ is the mass ratio, K is the stiffness ratio, and s is the dimensionless rotor speed;

[0088] Step S16: Compare the real part of the largest characteristic root among the characteristic roots of the determinant with 0. If it is less than 0, it means that the rotor oil accumulation is stable. If it is equal to 0, it is the critical state. If it is greater than 0, it means that the rotor oil accumulation is unstable.

[0089] Step S2: Keep the fuel tank 3 stationary and pour a certain amount of water into the fuel tank 3;

[0090] Step S3: The motor drives the rotor to rotate, increasing its speed from 0 to a preset stable state. Record the rotor speed at the stable state and turn off the motor;

[0091] The preset stable state is that the amplitude of the fuel tank 3 is less than a preset threshold.

[0092] Step S4: Analyze the rotor stability based on the rotor speed at the stable state and the rotor oil accumulation fault model;

[0093] Step S5: Repeat Step S2 - Step S4. If the analysis results of the rotor stability are the same twice, pour a certain amount of oil into the fuel tank 3 and execute Step S3 - Step S4 to complete the analysis of the rotor oil accumulation stability. Otherwise, repeat Step S2 - Step S4 until the analysis result of the rotor stability is the same as that in Step S4.

[0094] In summary, the present invention designs a rotor oil accumulation test platform and method, which accurately monitors and controls the test process, making the rotor oil accumulation test platform have the advantages of combining theory with experiment, being portable, easy to operate, and having accurate test results.

[0095] The embodiments of the present invention have been described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the knowledge scope of those of ordinary skill in the art, various changes can be made without departing from the purpose of the present invention.

Claims

1. A rotor oil accumulation test platform for analyzing the stability of rotor oil accumulation, characterized in that, Including: Steel frame, device plate, fuel tank, bearing, bearing seat, rotor, and stabilizing member; The steel frame is composed of a rectangular upper bottom plate and a lower bottom plate with the same size, and four columns with the same size. The two ends of the four columns are respectively fixedly connected to the four corners of the upper bottom plate and the lower bottom plate, and the upper bottom plate and the lower bottom plate are parallel and opposite to each other; The stabilizing member is used to install the device plate between the upper bottom plate and the lower bottom plate of the steel frame. The number of the stabilizing members is the same as the number of the columns of the steel frame, and the sizes and shapes of the stabilizing members are the same. One end of the stabilizing member is provided with an opening, and the shape of the opening corresponds to the cross-section of the column of the steel frame for socket-fixing and installing on the column of the steel frame. The other end of the stabilizing member has a threaded hole for fixedly installing the device plate. When the stabilizing members are respectively installed on the columns of the steel frame, they are located on the same horizontal plane; The device plate is a rectangular plate with the same size as the upper bottom plate and the lower bottom plate of the steel frame. The center position of the device plate has a preset number of threaded holes for fixedly installing the bearing seat. The four corners of the device plate are provided with openings, and the shape of each opening corresponds to the cross-section of the column of the steel frame. Each column of the steel frame respectively passes through the openings at the four corners of the device plate, so that the device plate is socket-fixed between the upper bottom plate and the lower bottom plate of the steel frame; The device plate has threaded holes, and the positions of the threaded holes respectively correspond to the threaded holes on the stabilizing members, so that the device plate is fixed on the stabilizing members between the steel frames by screws; The bearing seat is used to connect the bearing. Its base is a rectangular structure with threaded holes at the four corners, and the threaded holes at the base of the bearing seat correspond to the threaded holes of the device plate. The bearing seat is fixedly connected to the device plate by screws; The bearing is connected to the bearing seat and is connected to the fuel tank through the rotor. When the rotor is driven by a motor, the fuel tank rotates driven by the rotor.

2. A rotor oil accumulation test method, characterized in that, For a rotor oil accumulation test platform according to claim 1, perform the following steps S1 - step S5 to complete the analysis of rotor oil accumulation stability by constructing a rotor oil accumulation fault model: Step S1: Construct a rotor model. According to the dynamic parameters of the rotor, based on the NS equation, establish a fluid-structure interaction model, and theoretically establish a rotor oil accumulation fault model; Step S2: Keep the fuel tank stationary and pour a certain amount of water into the fuel tank; Step S3: The motor drives the rotor to rotate, and its speed increases from 0 to a preset stable state. Record the rotor speed in the stable state, and then turn off the motor; Step S4: Based on the rotor speed in the stable state and the rotor oil accumulation fault model, analyze the rotor stability; Step S5: Repeat step S2 - step S4. If the analysis results of the rotor stability are the same twice, then pour a certain amount of oil into the fuel tank and perform step S3 - step S4 to complete the analysis of rotor oil accumulation stability. Otherwise, repeat step S2 - step S4 until the analysis result of the rotor stability the same as that in step S4 is obtained.

3. The rotor oil accumulation test method according to claim 2, characterized in that, The preset stable state in step S3 is that the amplitude of the fuel tank is less than a preset threshold.

4. The rotor oil accumulation test method according to claim 2 or 3, characterized in that, The method for theoretically establishing a rotor oil accumulation fault model in step S1 is as follows: Step S11: Construct a rotor model as follows: where \(r\) and \(\varphi\) are the radius and rotation angle of the rotor respectively, \(u\) and \(v\) are the rotational speeds of the rotor in the directions of radius \(r\) and rotation angle \(\varphi\) at time \(t\), \(p\) is the pressure, \(\rho\) is the liquid density, \(\varepsilon_1\), \(\varepsilon_2\) are perturbation parameters, \(\Omega\) is the angular velocity of the rotor, \(\lambda=\alpha + i\omega\), \(\alpha\) is the stability parameter, and \(\omega\) is the whirling frequency; For an incompressible fluid, the continuity equation is as follows: For a non-viscous fluid, the boundary conditions are as follows: where \(a\) represents the inner wall of the rotor, \(R\) is the free surface function, and its expression is \(R = b+\eta_1(\varphi_1,t)\cdot\varepsilon_1+\eta_2(\varphi_2,t)\cdot\varepsilon_2\). When \(R = b\), \(b\) is the position of the undisturbed free surface, and the following equation is derived: Step S12: Using the perturbation method, with perturbation parameters \(\varepsilon_1\), \(\varepsilon_2\), linearize the rotor model and ignore the higher-order terms, then there is the following equation: Substitute Equation (5) into the rotor model (1a)-(1b) to obtain the zero-order solutions \(u_0\), \(v_0\), \(p_0\) corresponding to the undisturbed rotor as follows: After perturbation, the momentum equations (1a)-(1b) that the first-order solutions need to satisfy are as follows: The corresponding continuity equation is as follows: The corresponding boundary conditions are as follows: \(u_1(a)=0\); \(u_2(a)=0\) (9a) p1(b) = -ρΩ 2 bη1; p2(b) = -ρΩ 2 bη2(9b) where \(\eta_1\), \(\eta_2\) are the response functions of the perturbation; Step S13: The expression of the rotor wall pressure is as follows: where \(p(a)\) represents the pressure on the inner wall \(a\) of the rotor, \(\varphi\) is the rotation angle of the rotor, \(\sigma\), \(\gamma\) are a pair of auxiliary quantities, and \(i\) is a complex number, specifically as follows: \(\gamma=\lambda - i\Omega\); \(\sigma=\lambda + i\Omega\) (11) \(\Gamma\) is specifically as follows: Replace \(\lambda\), \(\varepsilon_1\), \(\varepsilon_2\), \(\gamma\), \(\Gamma\) with \(iw\), \(\varepsilon\), \(-i\varepsilon\), \(i\sigma\), \(\gamma\) respectively, where \(\Gamma\) is the filling ratio, \(w\) is the dimensionless eigenvalue, and \(\varepsilon_1\), \(\varepsilon_2\) are the perturbation parameters; Step S14: When the fluid is non-viscous, the shear stress is not considered, and the resultant force on the inner wall of the rotor in the rotating coordinate system is obtained by integrating the pressure on the inner wall of the rotor: where \(a\) is the radius of the rotor wall and \(L\) is the length of the rotor; The resultant force on the inner wall of the rotor in the stationary coordinate system is as follows: F X = F x cos(Ωt) - F y sin(Ωt) (14a) F Y = F x sin(Ωt) + F y cos(Ωt) (14b) Combining Equations (10)-(14), the following equation is finally obtained: where: where m1 is the mass of the liquid required to completely fill the fuel tank cavity, and m1 = ρπa 2 L(17), and ε is the perturbation coefficient; Step S15: Establish the equilibrium equation as follows: [M]\(\{\varepsilon\}+[C]\{\varepsilon\}+[S]\{\varepsilon\}=-[F]\{\varepsilon\}\) (18) where m r is the mass of the empty rotor, c X , c Y are dimensionless external damping coefficients, and k X , k Y are the stiffnesses in the main directions; According to the above equation, a homogeneous system of equations is obtained, and its non-singular solution only exists when the determinant of this homogeneous system of equations is equal to 0. According to the determinant condition, the characteristic equation is as follows: b8w 8 +b7w 7 +b6w 6 +b5w 5 +b4w 4 +b3w 3 +b2w 2 +b1w 1 +b0 = 0 (20) where: b2 = 2Ks 2 (Γ 2 + 3Γ + 2)+(1 + K)(Γ + 1)(2μ + Γ + 1)s 4 + C X C Y (Γ + 1) 2 s 4 b1 = s 4 (Γ + 1) 2 (KC X + C Y ) b0 = Ks 4 (1 + Γ) 2 where \(\mu\) is the mass ratio, \(K\) is the stiffness ratio, and \(s\) is the dimensionless rotor rotational speed; Step S16: Compare the real part of the largest eigenvalue among the eigenvalues of the determinant with 0. If it is less than 0, it means that the rotor is stable with oil accumulation. If it is equal to 0, it is the critical state. If it is greater than 0, it means that the rotor is unstable with oil accumulation.

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