Low-pressure turbine inclined drum disk structure for high-speed dynamic balance and oil accumulation prevention and calibration method

Abstract

The present invention discloses a low-pressure turbine inclined drum disc structure and a calibration method for preventing oil accumulation during high-speed dynamic balancing, belonging to the technical field of low-pressure turbine structure design. The low-pressure turbine inclined drum disc structure for preventing oil accumulation during high-speed dynamic balancing includes a low-pressure rotor and a drum disposed between the low-pressure rotors. The inner cavity of the drum is communicated with the lubricating oil overflow channel of the low-pressure turbine bearing assembly. The side wall of the drum is inclined relative to the axis of the low-pressure turbine, causing the drum to be in a conical surface. An oil hole is opened at one end of the side wall of the drum that is at a greater distance from the axis of the low-pressure turbine, so that the lubricating oil in the inner cavity of the drum is discharged from the oil hole under the action of centrifugal force and the guiding of the side wall of the drum. This application can solve the technical problem that the oil drainage of the straight-drum low-pressure turbine rotor is not timely, resulting in excessive vibration during high-speed dynamic balancing.

Description

Technical Field

[0001] The present invention relates to the technical field of low-pressure turbine structure design, and particularly to a low-pressure turbine inclined drum disk structure and verification method for high-speed dynamic balance and oil accumulation prevention. Background Art

[0002] The low-pressure turbine shaft is a flexible shaft, and its operating speed is higher than the bending critical speed. By performing high-speed dynamic balance on the low-pressure turbine rotor, the unbalance amount of the low-pressure turbine rotor is reduced, thereby controlling the deflection of the low-pressure turbine shaft at the critical speed and operating speed, and ensuring good vibration and safe and reliable operation of the engine.

[0003] During the high-speed dynamic balance process, since there is no high-pressure gas seal for the lubricating oil, the lubricating oil will enter the drum through the gaps between the bearing chambers and the sealing rings. If it is not removed in time, the lubricating oil will accumulate at the bottom of the drum. As the lubricating oil accumulates, the unbalance amount of the low-pressure turbine rotor increases, and the vibration during high-speed dynamic balance exceeds the limit, resulting in the inability to reach the required critical speed. Currently, in order to solve the problem of lubricating oil accumulation in the low-pressure turbine drum structure, a straight drum design is generally adopted. Air holes are provided on the straight drum, and during the high-speed dynamic balance of the low-pressure rotor, the lubricating oil is thrown out of the air holes by centrifugal force.

[0004] The existing straight-drum low-pressure turbine rotor can prevent lubricating oil from accumulating at the bottom of the drum and meet the normal operation requirements of the low-pressure rotor during high-speed dynamic balance. However, for the straight-drum low-pressure turbine rotor, if the aperture of the air hole is too small or the punching position is inappropriate, the lubricating oil may not be discharged in time, still resulting in excessive vibration during high-speed dynamic balance. Summary of the Invention

[0005] The present invention provides a low-pressure turbine inclined drum disk structure and verification method for high-speed dynamic balance and oil accumulation prevention to solve the technical problem of excessive vibration during high-speed dynamic balance caused by untimely oil discharge of the straight-drum low-pressure turbine rotor.

[0006] According to one aspect of the present invention, there is provided a verification method for a low-pressure turbine inclined drum disk structure for high-speed dynamic balance and oil accumulation prevention, characterized in that:

[0007] The low-pressure turbine inclined drum disk structure for high-speed dynamic balance and oil accumulation prevention includes a low-pressure rotor and a drum provided between the low-pressure rotors. The inner cavity of the drum is communicated with the lubricating oil overflow channel of the low-pressure turbine bearing assembly. The side wall of the drum is inclined relative to the axis of the low-pressure turbine, making the drum in a conical surface. An oil hole is provided at one end of the side wall of the drum with a larger distance from the axis of the low-pressure turbine, so that the lubricating oil in the inner cavity of the drum is discharged from the oil hole under the action of centrifugal force and the guiding of the side wall of the drum;

[0008] The verification method includes the following steps:

[0009] Calculate the radial velocity V of the lubricating oil at the outlet of the rotating part according to the rotational speed ω of the rotating part, the radius R1 at the inlet of the oil hole, the radius R2 at the outlet of the oil hole, and the angle α between the oil hole and the shaft y2 , tangential velocity V z2 , axial velocity V x2 ; Calculate the injection velocity V2 of the lubricating oil at the outlet of the rotating part according to the radial velocity V y2 , tangential velocity V z2 , axial velocity V x2 ; Calculate the equivalent pressure difference P of the lubricating oil at the outlet of the rotating part according to the injection velocity V2 of the lubricating oil at the outlet of the rotating part, the lubricating oil density ρ, and the velocity coefficient η; Calculate the lubricating oil mass flow rate m at the outlet of the rotating part according to the equivalent pressure difference P of the lubricating oil at the outlet of the rotating part, the lubricating oil density ρ, the number of oil holes Z, and the oil hole diameter d; If the lubricating oil mass flow rate m at the outlet of the rotating part is greater than n times the lubricating oil mass flow rate of the nozzle during high-speed dynamic balancing, where n ranges from 2 to 5, it indicates that the configuration of the oil holes can timely discharge the lubricating oil entering the inclined drum, ensuring the normal progress of the high-speed dynamic balancing of the low-pressure rotor; The unit of the lubricating oil density ρ is kg / m3, the velocity coefficient η = 0.9 - 0.95, the unit of the rotational speed ω of the rotating part is rad / s, the unit of the radius R1 at the inlet of the oil hole is mm, the unit of the radius R2 at the outlet of the oil hole is mm, and the unit of the oil hole diameter d is mm

[0010] Optionally, calculate the radial velocity V of the lubricating oil at the outlet of the rotating part according to the rotational speed ω of the rotating part, the radius R1 at the inlet of the oil hole, the radius R2 at the outlet of the oil hole, and the angle α between the oil hole and the shaft y2 , tangential velocity V z2 , axial velocity V x2 The formula is:

[0011] V y2 = ω * (R2 2 - R1 2 ) 1 / 2 / 1000;

[0012] V z2 = ω * R2 / 1000;

[0013] V x2 = V y2 / tan(α);

[0014] Calculate the injection velocity V2 of the lubricating oil at the outlet of the rotating part according to the radial velocity V y2 , tangential velocity V z2 , axial velocity V x2 The formula is: V2 = (V y2 2 + V z2 2 + V x2 2 )1 / 2 .

[0015] Optionally, the formula for calculating the equivalent pressure difference P of the lubricating oil at the outlet of the rotating part according to the injection speed V2 of the lubricating oil at the outlet of the rotating part, the lubricating oil density ρ, and the velocity coefficient η is: P = 0.5 * ρ * (V2 / η) 2 / 1000000.

[0016] Optionally, the formula for calculating the lubricating oil mass flow rate m of the lubricating oil at the outlet of the rotating part according to the equivalent pressure difference P of the lubricating oil at the outlet of the rotating part, the lubricating oil density ρ, the number of oil holes Z, and the oil hole diameter d is: m = 3.14 * (2 * ρ * P) 1 / 2 * d 2 / (4 * Z).

[0017] Optionally, the oil holes are perpendicular to the inner wall of the drum.

[0018] Optionally, a plurality of the oil ports are evenly distributed along the axial direction of the drum.

[0019] Optionally, the low-pressure turbine bearing assembly includes a bearing housing, a low-pressure turbine short shaft, and two bearings disposed between the bearing housing and the low-pressure turbine short shaft. A lubricating oil nozzle connected to the oil inlet pipe is installed on the bearing housing, and a clearance between the bearing cavity and the bearing housing forms a lubricating oil overflow channel.

[0020] Optionally, a sealing ring is disposed between the bearing housing and the low-pressure turbine short shaft, and the sealing ring blocks the lubricating oil overflow channel to reduce the amount of lubricating oil overflow.

[0021] Optionally, the preset configuration of the position, diameter, and number of the oil holes enables the mass flow rate of the lubricating oil at the oil holes to be greater than the mass flow rate of the lubricating oil of the nozzle during high-speed dynamic balancing.

[0022] In summary, the present application includes at least one of the following beneficial technical effects:

[0023] By arranging the rotor cone surface of the drum to be inclined with respect to the low-pressure pivot, the drum conical surface structure is formed, so that by using the centrifugal force generated by high-speed rotation and the guiding action of the drum rotor surface, the lubricating oil entering the inner cavity of the drum rapidly flows downstream away from the axis along the trend surface. This not only prevents the accumulation of oil liquid inside the low-pressure rotor, but also effectively reduces the problem of excessive high-speed dynamic balance vibration caused by the accumulation of oil liquid;

[0024] The position, diameter, and number of the oil holes are all preset-configured to ensure that the mass flow rate of the oil holes can be greater than the mass flow rate of the nozzle oil supply in the high-speed dynamic balance state (usually 2 to 5 times the nozzle flow rate). The design ensures that during high-speed operation, the lubricating oil entering the inclined drum can be discharged in time and will not accumulate inside the rotor, thereby avoiding abnormal dynamic balance vibration caused by the accumulation of oil liquid.

[0025] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The present invention will be further described in detail below with reference to the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The drawings forming a part of this application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0027] Figure 1 is a schematic diagram of the low-pressure turbine inclined drum disk structure for high-speed dynamic balance and oil accumulation prevention of the present invention;

[0028] Figure 2 is a schematic diagram of the oil hole position of the present invention;

[0029] Figure 3 is a schematic diagram of the oil hole calculation parameters.

[0030] Legend:

[0031] 1. Low-pressure shaft; 2. Inlet oil pipe; 3. Oil supply seat; 4. Lubricating oil nozzle; 5. Bearing; 6. Low-pressure turbine short shaft; 7. Sealing ring; 8. Support seat; 9. Bearing seat; 10. Low-pressure turbine rotor; 11. Oil hole. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] The embodiments of the present invention will be described in detail below with reference to the drawings. However, the present invention can be implemented in many different ways defined and covered by the following.

[0033] The following combines the attached Figures 1-3 to further describe this application in detail.

[0034] The embodiment of this application discloses a low-pressure turbine inclined drum disk structure for high-speed dynamic balance and oil accumulation prevention.

[0035] Referring to Figure 1 , the low-pressure turbine inclined drum disk structure for high-speed dynamic balance and oil accumulation prevention includes a low-pressure rotor and a drum disposed between the low-pressure rotors. The inner cavity of the drum is communicated with the lubricating oil overflow channel of the low-pressure turbine bearing assembly. The side wall of the drum is inclined relative to the axis of the low-pressure turbine so that the drum is in a conical surface. An oil hole is opened at one end of the side wall of the drum with a larger distance from the axis of the low-pressure turbine, so that the lubricating oil in the inner cavity of the drum is discharged from the oil hole under the action of centrifugal force and the guiding of the side wall of the drum.

[0036] The low-pressure rotor constitutes the core rotating component of the turbine. The drum, serving as the oil chamber inside the rotor, is mainly responsible for collecting and discharging the lubricating oil that enters the rotor interior to prevent the accumulation of oil, which could lead to abnormal dynamic balance and excessive vibration. To address the problem of traditional straight-drum structures where lubricating oil stays in the rotor due to untimely oil drainage, an inclined-drum structure is adopted. This structure enables the lubricating oil to quickly flow towards the oil holes and be discharged by means of centrifugal force and guiding action, ensuring the stability of the dynamic balance state of the rotor during high-speed operation. The inclined drum is installed inside the low-pressure rotor, and its inner cavity is connected to the lubricating oil overflow channel of the low-pressure turbine bearing assembly. The side wall of this drum is not perpendicular to the rotor axis but is set at a specific inclination angle, forming a structure similar to a conical surface. The specific value of the inclination angle α needs to be determined according to the actual rotor speed, lubricating oil properties, and oil drainage requirements. Generally, during design, it is necessary to ensure that the inclination angle can provide sufficient guiding action without negatively affecting the rigidity and balance of the overall rotor structure. Through the inclined setting, the lubricating oil inside the drum is more likely to concentrate and flow along the inclined surface towards the oil holes under the action of centrifugal force, thereby improving the oil drainage efficiency and preventing the lubricating oil from staying in the rotor for a long time. The conical surface structure can form an obvious lubricating oil flow channel during high-speed rotation, effectively improving the lubricating oil drainage path.

[0037] Refer to Figure 1 and Figure 2 , the oil holes are perpendicular to the inner wall of the drum. The oil holes are perpendicular to the inner wall of the drum, ensuring that the oil outlet direction of the oil discharge port is consistent with the normal direction of the inner wall of the drum. This can ensure that under the action of high-speed rotation of the rotor and centrifugal force, the oil can be ejected directly and stably from the oil holes, avoiding the deviation of the oil flow direction caused by the inclination of the hole mouth, and ensuring that the oil can quickly leave the inside of the drum. When the oil holes are perpendicular to the inner wall of the drum, the oil does not need to experience additional flow bending or deflection at the hole mouth during the discharge process, thereby reducing the flow resistance and energy loss caused by angle changes. The oil leaves in the form of a relatively pure jet flow, which helps to improve the oil drainage efficiency, ensure that the oil can be discharged in the shortest time, prevent the oil from staying and accumulating. At the same time, it can make the discharged oil avoid flowing along the inner wall of the drum as much as possible, preventing the oil from flowing back or staying on the inner wall due to friction or disturbance with the inner wall. In this way, the oil can quickly leave the oil hole area, thereby reducing the residence time of the oil inside the drum and reducing the risk of oil accumulation.

[0038] There are multiple oil ports evenly distributed along the axial direction of the drum. By evenly distributing the oil ports along the inner cavity of the drum, it ensures that the lubricating oil in the inner cavity of the drum can be fully discharged, avoiding the accumulation of oil in local areas. This design utilizes the action of centrifugal force and concentrated holes to achieve a continuous and precise oil drainage channel. This evenly distributed design effectively prevents the risks of unbalanced moments and vibrations caused by local oil retention, optimizes the flow field, accurately calculates the oil flow pressure and dispersion, and further improves the stability and dynamic performance balance of the low-pressure vortex during high-speed operation.

[0039] The low-pressure turbine bearing assembly includes a bearing housing, a low-pressure turbine short shaft, and two bearings disposed between the bearing housing and the low-pressure turbine short shaft. A lubricating oil nozzle connected to an oil inlet pipe is installed on the bearing housing, and a clearance between the bearing cavity and the bearing housing forms a lubricating oil overflow channel.

[0040] During actual assembly, first, the bearing housing is fixed at a predetermined position on the low-pressure pivot. Then, the first bearing, the low-pressure pivot, and the second bearing are sequentially installed on the central axis inside the bearing housing, ensuring that the short shaft is coaxial with the bearing housing and is immediately inserted into the bearing. The oil inlet pipe is arranged on the oil supply seat and is connected to the lubricating oil nozzle. The lubricating oil nozzle installed on the bearing housing and connected to the oil inlet pipe precisely injects lubricating oil into the bearing cavity, and the clearance between the bearing housing and the bearing cavity constitutes a lubricating oil overflow channel, which guides the excessive or leaked lubricating oil into the inner cavity of the inclined drum, cooperating with the preset oil drain hole configuration structure in the drum to jointly optimize the overall oil drainage effect and ensure the stable operation of the low-pressure bearing under high-speed dynamic balance.

[0041] A sealing ring is provided between the bearing housing and the low-pressure turbine short shaft, and the sealing ring seals the lubricating oil overflow channel to reduce the amount of lubricating oil overflow. The sealing ring provided between the bearing housing and the low-pressure round shaft short shaft mainly functions to seal the lubricating oil overflow channel, thereby effectively reducing the excessive overflow of lubricating oil caused by centrifugal force or other related factors. Specifically, during the manufacturing process, a special sealing groove is machined at one end of the bearing housing or the low-pressure round shaft short shaft, and the position of this groove is closely connected to the lubricating oil overflow channel. The sealing ring is made of wear-resistant and high-temperature-resistant materials, usually rubber or metal composite materials, and is designed as a snap or press-in structure. During installation, the sealing ring is accurately inserted into the sealing groove, forming a tight contact between the bearing housing and the short shaft. This sealing configuration can remain stable under high-speed rotation and vibration conditions, effectively preventing a large amount of lubricating oil from jumping through the overflow channel, while ensuring that enough oil can still lubricate the bearing. This not only ensures the lubrication performance of the bearing but also avoids excessive oil from entering the rotor interior, thus affecting the high-speed dynamic balance.

[0042] The preset configuration of the position, diameter, and number of oil holes enables the mass flow rate of lubricating oil through the oil holes to be greater than the mass flow rate of lubricating oil of the nozzle during high-speed dynamic balance. Through the optimized position, diameter, and number, the mass flow rate of oil drainage can be precisely controlled, so that even during high-speed rotation, the flow formed by the centrifugal force and guiding action of the oil is fast enough to input the oil introduced by the oral nozzle oil supply, thereby maintaining the dynamic balance of the oil inside the piston and reducing the imbalance caused by uneven oil. During design, the specific position, diameter, and number of oil holes need to be determined through theoretical calculation, numerical simulation, and experimental verification.

[0043] In traditional straight drum designs, additional support structures (such as reinforcing ribs or thickened spokes) are usually required at the bottom to ensure sufficient stiffness and strength, preventing vibrations and deformations caused by oil accumulation. However, in the inclined drum structure, with its inclined design and the guiding effect of centrifugal force, the lubricating oil entering the drum can flow out along the inclined plane faster, reducing the possibility of oil staying at the bottom. Therefore, no additional reinforcement measures are needed to support the bottom of the drum, which not only reduces the structural weight but also simplifies the manufacturing process. In addition, by optimizing the force distribution, the overall stiffness of the inclined drum structure is maintained while reducing the material usage, thus achieving the goal of weight reduction.

[0044] Weight reduction has many positive effects on the performance of aero-engines. First, it improves fuel efficiency and reduces the engine thrust-to-weight ratio, enabling the aircraft to fly farther with less fuel. Second, after the engine mass is reduced, the maneuverability of the aircraft is significantly improved. Especially in application scenarios with extremely high flexibility requirements such as fighter jets, weight reduction can enhance the climb rate, turning speed, and overall tactical capabilities. In addition, reducing the structural weight can also reduce the inertia of the turbine rotor, reduce vibrations and imbalance phenomena, improve the stability and reliability of the engine, thus extending the service life and reducing maintenance costs. These advantages make weight reduction a key optimization direction in modern aero-engine design.

[0045] Referring to Figure 3 , the present invention also provides a verification method for a low-pressure turbine inclined drum disk structure for high-speed dynamic balance and anti-oil accumulation, which includes the following steps:

[0046] S100, calculate the radial velocity V of the lubricating oil at the outlet of the rotating part according to the rotational speed ω of the rotating part, the radius R1 at the inlet of the oil hole, the radius R2 at the outlet of the oil hole, and the angle α between the oil hole and the axis y2 , the tangential velocity V z2 , and the axial velocity V x2 ;

[0047] S200, calculate the injection velocity V2 of the lubricating oil at the outlet of the rotating part according to the radial velocity V y2 , the tangential V z2 , and the axial velocity V x2 ;

[0048] S300, calculate the equivalent pressure difference P of the lubricating oil at the outlet of the rotating part according to the injection velocity V2 of the lubricating oil at the outlet of the rotating part, the lubricating oil density ρ, and the velocity coefficient η;

[0049] S400, calculate the lubricating oil mass flow rate m at the outlet of the rotating part according to the equivalent pressure difference P of the lubricating oil at the outlet of the rotating part, the lubricating oil density ρ, the number of oil holes Z, and the oil hole diameter d;

[0050] For S500, if the lubricating oil mass flow rate \(m\) at the outlet of the rotating part is greater than \(n\) times the lubricating oil mass flow rate of the nozzle during high-speed dynamic balancing, where \(n\) ranges from 2 to 5, it indicates that the configuration of the oil holes can timely discharge the lubricating oil entering the inclined drum, ensuring the normal progress of the high-speed dynamic balancing of the low-pressure rotor.

[0051] The unit of lubricating oil density \(\rho\) is \(kg / m^3\), the velocity coefficient \(\eta = 0.9 - 0.95\), the rotational speed \(\omega\) of the rotating part is in units of \(rad / s\), the radius \(R1\) at the inlet of the oil hole is in units of \(mm\), the radius \(R2\) at the outlet of the oil hole is in units of \(mm\), and the diameter \(d\) of the oil hole is in units of \(mm\).

[0052] Based on the basic principles of fluid mechanics and rotational motion, S100 divides the overall flow of the oil at the outlet of the oil hole into three gradients: clearance, tangential, and connection, thus comprehensively describing the dynamic characteristics of the oil during the discharge process; specifically, through the angle \(\omega\) of the rotating part, as well as the radius \(R1\) at the inlet and radius \(R2\) at the outlet of the hole, the radial velocity generated due to the centrifugal force can be calculated, which reflects the acceleration effect of the oil when rotating from a smaller area radius to an incremental radius; at the same time, due to the overall rotational motion of the rotor, the oil at the outlet will inevitably obtain a tangential velocity \(V\) y2 proportional to the outlet radius \(V\) z2 , and this part of the velocity reflects the kinetic energy obtained by the oil as it rotates with the rotor; in addition, due to the angle \(\alpha\) between the oil hole and the adjacent series angle, this causes the oil to not only move upward in the clearance and tangential velocities during spraying, but also generate a quantity \(V\) along the integrity x2 , which is obtained by taking the tangent of the clearance velocity, further supplementing the complete description of the overall movement of the oil; by calculating these three quantities separately, the overall spraying velocity of the oil at the outlet of the oil hole can be determined, providing the necessary data support for calculating the equivalent pressure difference \(P\) and mass flow rate based on the spraying velocity, oil density \(\rho\), and velocity factor \(\eta\) subsequently.

[0053] Specifically, according to the rotational speed \(\omega\) of the rotating part, the radius \(R1\) at the inlet of the oil hole, the radius \(R2\) at the outlet of the oil hole, and the angle \(\alpha\) between the oil hole and the axis, the radial velocity \(V\) y2 , tangential velocity \(V\) z2 , and axial velocity \(V\) x2 of the lubricating oil at the outlet of the rotating part are calculated by the following formulas:

[0054] \(V\) y2 = \(\omega\times(R2\) 2 - \(R1\) 2 ) 1 / 2 / 1000;

[0055] \(V\) z2 = \(\omega\times R2 / 1000\);

[0056] \(V\) x2 = \(V\) y2 / \(\tan(\alpha)\).

[0057] S200 assumes the movement speed of the oil at the oil hole outlet as a three-dimensional vector, and uses the Pythagorean theorem to combine the gradients of each movement, that is, the bearing speed V y2 , the tangential speed V z2 and the filling speed V x2 as the three gradients of the vector in the orthogonal coordinate system. By squaring, summing and then taking the square root, the overall injection speed V2 is obtained, so as to completely describe the total kinetic energy of the oil when it leaves the rotating part; the core of this method lies in realizing that in rotating machinery, the oil does not move in a single direction, but forms a complex three-dimensional flow field under the action of centrifugal force, rotational inertia and geometric guidance. By decomposing the complex movement into simple orthogonal speeds, the total injection volume of the oil can be accurately calculated using the classical vector synthesis principle.

[0058] Specifically, according to the radial speed V y2 , the tangential speed V z2 , and the axial speed V x2 , the formula for calculating the injection speed V2 of the lubricating oil at the outlet of the rotating part is: V2 = (V y2 2 + V z2 2 + V x2 2 ) 1 / 2 .

[0059] S300 is based on the principle of energy conservation velocity and the conversion relationship between kinetic energy and pressure energy in fluid dynamics. By converting the injection V2 of the lubricating oil at the outlet of the rotating part into the corresponding kinetic energy density (i.e., 0.5ρV2 2 ) to reflect the energy existing in the oil. However, due to energy losses such as friction and turbulence in the actual flow, in order to more accurately reflect the actual movement state of the oil, a velocity coefficient η is introduced to correct the injection speed, so that the corrected speed (V2 / η) can more truly represent the effective flow rate of the oil. Thus, the corrected kinetic energy density 0.5ρ(V2 / η) 2 is used to calculate the equivalent pressure difference P formed by the oil at the outlet, and this equivalent pressure difference represents the effective driving force generated by the conversion of kinetic energy into static pressure during the high-speed injection of the oil.

[0060] Specifically, according to the injection speed V2 of the lubricating oil at the outlet of the rotating part, the lubricating oil density ρ and the velocity coefficient η, the formula for calculating the equivalent pressure difference P of the lubricating oil at the outlet of the rotating part is: P = 0.5 * ρ * (V2 / η) 2 / 1000000.

[0061] The principle of S300 is based on the orifice flow theory and the law of conservation of energy in fluid mechanics. That is, the equivalent pressure difference P formed at the outlet of the rotating part by the lubricating oil is used as the driving force. The mass flow rate m of the oil passing through the orifice is deduced through the combined relationship with the oil density ρ and the geometric parameters of the orifice (orifice diameter d and number Z). Its basic idea is to regard each orifice as a small nozzle. The oil flows through the orifice at a certain speed under the action of the equivalent pressure difference. The cross-sectional area of the orifice is proportional to the square of the diameter d, and the total flow rate of multiple orifices is the accumulation of the flow rates of individual orifices. Therefore, by calculating the theoretical flow velocity of the oil at a single orifice and combining it with the density of the oil and the effective area of the orifice, the mass flow rate of the oil at that place can be obtained. The introduction of the equivalent pressure difference P is to consider the difference between the actual flow velocity and the ideal flow velocity caused by factors such as friction, turbulence, and energy loss in actual flow, so as to make the calculation closer to the actual working state, and then provide a basis for designers to quantitatively evaluate whether the orifice configuration can achieve sufficient oil discharge under high-speed rotation and high-speed dynamic balance conditions, ensure that the excess lubricating oil can be discharged in time, and prevent the oil from accumulating inside the rotor and affecting the dynamic balance and the stable operation of the overall system.

[0062] Specifically, the formula for calculating the mass flow rate m of the lubricating oil at the outlet of the rotating part according to the equivalent pressure difference P of the lubricating oil at the outlet of the rotating part, the lubricating oil density ρ, the number of orifices Z, and the orifice diameter d is: m = 3.14 * (2 * ρ * P) 1 / 2 * d 2 / (4 * Z).

[0063] S500 ensures that the oil discharge capacity far exceeds the oil supply volume by setting that the mass flow rate m of the lubricating oil at the outlet of the rotating part must be 2 to 5 times greater than the oil supply mass flow rate of the nozzle. As a result, the lubricating oil entering the inclined drum can be quickly discharged under the powerful centrifugal force and guiding action generated by high-speed rotation, and no oil accumulation phenomenon will occur inside the rotor and the inclined drum, avoiding local imbalance and excessive vibration caused by uneven oil distribution. At the same time, this design ensures that the bearing can still obtain a stable and sufficient lubricating oil supply, preventing excessive oil from interfering with the dynamic balance. By quantitatively comparing the ratio of the oil discharge and oil supply flow rates, designers can optimize the number, position, and diameter of the orifices during the design stage to ensure that the oil discharge system can timely and effectively discharge the excess lubricating oil in actual working conditions, maintain the overall oil balance of the rotor, and thus achieve stable, reliable, and low-vibration operation of the low-pressure rotor under high-speed operation.

[0064] The principle of the present invention lies in designing a low-pressure turbine rotor system with an inclined drum structure and optimized oil hole configuration. On the premise of ensuring bearing lubrication, efficient oil discharge is achieved, thereby preventing unbalanced vibration caused by oil accumulation inside the rotor and in the inclined drum. The core lies in utilizing the centrifugal force generated by the high-speed rotation of the rotor and the guiding effect of the drum, enabling the lubricating oil entering the inclined drum to flow along the inner wall of the drum to the oil holes preset on the outer side for discharge. Through the precise design and configuration of the geometric parameters of the oil holes (such as the radii at the inlet and outlet of the oil holes, the angle between the oil hole and the rotor shaft, the oil hole diameter and quantity), it is ensured that the mass flow rate of oil discharge at the oil holes is significantly higher than the flow rate of oil supply from the bearing nozzle (usually required to be 2 to 5 times), so that under the high-speed dynamic balance condition, the excess oil can be quickly and effectively discharged. At the same time, a series of calculation methods based on the principles of fluid dynamics and energy conservation are adopted to decompose the radial, tangential, and axial velocity components of the oil at the outlet, and then synthesize the total injection velocity, and thereby calculate the equivalent pressure difference and the mass flow rate of the oil. This complete set of design solutions combining theory and practice ensures the dynamic balance of the supply and discharge of the lubricating oil, effectively avoiding rotor imbalance and vibration problems caused by oil accumulation, and thus ensuring the stability and reliability of the low-pressure turbine rotor during high-speed operation.

[0065] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. Calibration method for the low-pressure turbine inclined drum disc structure for high-speed dynamic balance and anti-oil accumulation, characterized in that: The low-pressure turbine inclined drum disc structure for high-speed dynamic balance and anti-oil accumulation includes a low-pressure rotor and a drum arranged between the low-pressure rotors. The inner cavity of the drum is communicated with the oil overflow channel of the low-pressure turbine bearing assembly. The side wall of the drum is inclined relative to the axis of the low-pressure turbine, making the drum in a conical shape. An oil hole is opened at one end of the side wall of the drum with a larger distance from the axis of the low-pressure turbine, so that the lubricating oil in the inner cavity of the drum is discharged from the oil hole under the action of centrifugal force and the guiding of the side wall of the drum; The calibration method includes the following steps: Calculate the radial velocity V, tangential velocity V, and axial velocity V of the lubricating oil at the outlet of the rotating part according to the rotational speed ω of the rotating part, the radius R1 at the inlet of the oil hole, the radius R2 at the outlet of the oil hole, and the angle α between the oil hole and the shaft. y2 , tangential velocity V z2 , and axial velocity V x2 ; According to the radial velocity V y2 , the tangential velocity V z2 , and the axial velocity V x2 calculate the injection velocity V2 of the lubricating oil at the outlet of the rotating part; Calculate the equivalent pressure difference P of the lubricating oil at the outlet of the rotating part according to the injection speed V2 of the lubricating oil at the outlet of the rotating part, the density ρ of the lubricating oil, and the velocity coefficient η; Calculate the lubricating oil mass flow rate m of the lubricating oil at the outlet of the rotating part according to the equivalent pressure difference P of the lubricating oil at the outlet of the rotating part, the density ρ of the lubricating oil, the number Z of oil holes, and the diameter d of the oil holes; If the lubricating oil mass flow rate m of the lubricating oil at the outlet of the rotating part is greater than n times the lubricating oil mass flow rate of the nozzle during high-speed dynamic balance, where n is taken from 2 to 5, it indicates that the configuration of the oil holes can timely discharge the lubricating oil entering the inclined drum, ensuring the normal progress of the high-speed dynamic balance of the low-pressure rotor; The unit of the density ρ of the lubricating oil is kg / m3, the velocity coefficient η = 0.9 - 0.95, the rotational speed ω of the rotating part is in the unit of rad / s, the radius R1 at the inlet of the oil hole is in the unit of mm, the radius R2 at the outlet of the oil hole is in the unit of mm, and the diameter d of the oil hole is in the unit of mm.

2. The calibration method for the low-pressure turbine inclined drum disc structure for high-speed dynamic balance and anti-oil accumulation according to claim 1, characterized in that: Calculate the radial velocity V, tangential velocity V z2 , and axial velocity V x2 of the lubricating oil at the outlet of the rotating part according to the rotational speed ω of the rotating part, the radius R1 at the inlet of the oil hole, the radius R2 at the outlet of the oil hole, and the angle α between the oil hole and the shaft. The formula is as follows: y2 and tangential velocity V z2 and axial velocity V x2 as follows: V y2 = ω * (R2 2 - R1 2 ) 1 / 2 / 1000; V z2 = ω * R2 / 1000; V x2 = V y2 / tan(α); According to the radial velocity V y2 , the tangential velocity V z2 , and the axial velocity V x2 , the formula for calculating the injection velocity V2 of the lubricating oil at the outlet of the rotating part is: V2 = (V y2 2 + V z2 2 + V x2 2 ) 1 / 2 .

3. The calibration method for the low-pressure turbine inclined drum disc structure for high-speed dynamic balance and anti-oil accumulation according to claim 2, characterized in that: The formula for calculating the equivalent pressure difference P of lubricating oil at the outlet of the rotating part according to the injection velocity V2 of the lubricating oil at the outlet of the rotating part, the density ρ of the lubricating oil, and the velocity coefficient η is: P = 0.5 * ρ * (V2 / η) 2 / 1000000.

4. The calibration method for the low-pressure turbine inclined drum disc structure for high-speed dynamic balance and anti-oil accumulation according to claim 3, characterized in that: The formula for calculating the lubricating oil mass flow rate \(m\) at the outlet of the rotating part based on the equivalent pressure difference \(P\) of the lubricating oil at the outlet of the rotating part, the lubricating oil density \(\rho\), the number of oil holes \(Z\), and the oil hole diameter \(d\) is: \(m = 3.14\times(2\times\rho\times P)\) 1 / 2 \(\times d\) 2 \( / (4\times Z)\).

5. The calibration method for the low-pressure turbine inclined drum disc structure for high-speed dynamic balance and anti-oil accumulation according to claim 1, characterized in that: The oil hole is perpendicular to the inner wall of the drum.

6. The calibration method for the low-pressure turbine inclined drum disc structure for high-speed dynamic balance and anti-oil accumulation according to claim 5, characterized in that: A plurality of the oil holes are evenly distributed along the axial direction of the drum.

7. The calibration method for the low-pressure turbine inclined drum disc structure for high-speed dynamic balance and anti-oil accumulation according to claim 5, characterized in that: The low-pressure turbine bearing assembly includes a bearing seat, a low-pressure turbine short shaft, and two bearings arranged between the bearing seat and the low-pressure turbine short shaft. A lubricating oil nozzle connected to the oil inlet pipe is installed on the bearing seat, and the gap between the bearing cavity and the bearing seat forms an oil overflow channel.

8. The calibration method for the low-pressure turbine inclined drum disc structure for high-speed dynamic balance and anti-oil accumulation according to claim 7, characterized in that: A sealing ring is arranged between the bearing seat and the low-pressure turbine short shaft, and the sealing ring blocks the oil overflow channel to reduce the amount of oil overflow.

9. The calibration method for the low-pressure turbine inclined drum disc structure for high-speed dynamic balance and anti-oil accumulation according to claim 7, characterized in that: The preset configurations of the positions, diameters, and numbers of oil holes enable the mass flow rate of the lubricating oil through the oil holes to be greater than the mass flow rate of the lubricating oil through the nozzles during high-speed dynamic balancing.

Images