CN-122020904-A - Method for controlling critical rotation speed of rotor by adjusting rigidity of bearing support system

CN122020904ACN 122020904 ACN122020904 ACN 122020904ACN-122020904-A

Abstract

The invention discloses a method for controlling the critical rotation speed of a rotor by adjusting the rigidity of a bearing support system, and relates to the field of heavy rotating equipment with bearing support. The method for controlling the critical rotation speed of the rotor through adjusting the rigidity of the bearing support system comprises the following steps of building a rigidity model of the bearing support system, marking calculated rigidity points as O1, marking support points at two ends as O2 and O3, collecting distance a between O1 and O2, collecting distance b between O1 and O3, collecting bearing rigidity K2 at the O2, collecting bearing rigidity K3 at the O3, obtaining bearing support rigidity K0 at the O1 according to a, b, K2 and K3, obtaining rigidity KM1 suffered by mass M1 at the O1 according to the bearing support rigidity K0 at the O1 and transverse rigidity K1 of a shaft at the O1, and obtaining the critical rotation speed of the rotor according to M1 and KM 1. The method calculates the rigidity of the mass of the point, and further obtains the critical rotation speed of the rotor, so that the critical rotation speed of the rotor can be controlled by adjusting the rigidity of the bearing support system, and resonance is avoided.

Inventors

ZHENG HONGHAI
WANG WEIFANG
ZHENG HONGWEI
ZHANG XINXING
XIE DONGYANG

Assignees

杭州大路实业有限公司

Dates

Publication Date: 20260512
Application Date: 20260204

Claims (10)

1. A method of controlling a critical rotational speed of a rotor by adjusting a stiffness of a bearing support system, comprising the steps of: Building a bearing support system rigidity model, marking calculated rigidity points as O1, and marking support points at two ends as O2 and O3; collecting a distance a between O1 and O2, and collecting a distance b between O1 and O3; collecting bearing support rigidity K2 at O2 and collecting bearing support rigidity K3 at O3; Obtaining bearing support rigidity K0 at O1 according to a, b, K2 and K3; Obtaining the rigidity KM1 suffered by the mass M1 at the O1 according to the bearing supporting rigidity K0 at the O1 and the transverse rigidity K1 of the shaft at the O1; From M1 and KM1, the critical rotation speed of the rotor is obtained.
2. Method for controlling the critical rotational speed of a rotor by adjusting the stiffness of a bearing support system according to claim 1, characterized in that the bearing support stiffness K0 at O1 is obtained from a, b, K2 and K3, comprising in particular: calculating the bearing support rigidity K0 at O1 through a first formula, wherein the first formula is that 1/K0=(1/K2)b 2 /(a+b) 2 +（1/K3）a 2 /(a+b) 2 。
3. Method for controlling the critical rotation speed of a rotor by adjusting the stiffness of a bearing support system according to claim 2, characterized in that the stiffness KM1 to which the mass M1 at O1 is subjected is obtained from the bearing support stiffness K0 at O1 and the shaft's own transverse stiffness K1 at O1, in particular comprising: calculating the stiffness KM1 to which the mass M1 at O1 is subjected by a second formula, wherein the second formula is that KM1=(K0*K1)/(K0+K1)。
4. A method of controlling a critical rotational speed of a rotor by adjusting the stiffness of a bearing support system according to claim 3, wherein the critical rotational speed of the rotor is obtained from M1 and KM1, comprising in particular: Calculating the critical rotation speed of the rotor through a third formula, wherein the third formula is that ω=√(KM1/M1)。
5. The method of controlling a critical rotational speed of a rotor by adjusting the stiffness of a bearing support system according to claim 1, further comprising the steps of: And the critical rotation speed of the rotor is adjusted by adjusting K2 and K3.
6. The method of controlling a critical rotational speed of a rotor by adjusting the stiffness of a bearing support system according to claim 5, comprising adjusting K2 and K3, in particular: a pull rod supporting rigidity is connected in series on the basis of the bearing supporting rigidity to form comprehensive rigidity; the comprehensive rigidity is adjusted by adjusting the supporting rigidity of the pull rod.
7. The method of controlling a critical rotational speed of a rotor by adjusting a stiffness of a bearing support system as claimed in claim 6, wherein adjusting the tie rod support stiffness comprises: calculating the support rigidity of the pull rod through a fourth formula, wherein the fourth formula is that K=e×a/L, where K is the tie rod support stiffness, E is the elastic modulus, a is the cross-sectional area of the tie rod, L is the length of the tie rod, From a and L, the tie rod support stiffness K is obtained.
8. The method of controlling a critical rotational speed of a rotor by adjusting the stiffness of a bearing support system according to claim 7, wherein calculating a and L comprises: calculating A and L by a fifth formula, wherein the fifth formula is N=E*A*X/L δ=N/A Wherein X represents deformation, delta is within the allowable strength range of the material, and N is the stress value of the supporting point.
9. The method of controlling a critical rotational speed of a rotor by adjusting a stiffness of a bearing support system according to claim 8, further comprising: the delta value is within the designed safety value; obtaining A according to delta and N; According to A, K, E, L is obtained.
10. The method of controlling a critical rotational speed of a rotor by adjusting the stiffness of a bearing support system according to claim 8, wherein: The a and the b are the same; or the a and b are different.

Description

Method for controlling critical rotation speed of rotor by adjusting rigidity of bearing support system Technical Field The invention relates to the field of heavy rotating equipment with bearing support, in particular to a method for controlling the critical rotating speed of a rotor by adjusting the rigidity of a bearing support system. Background Rotating machinery equipment has wide application, and the design of common rotating equipment is that a rotating shaft and a bearing are supported, and a shaft system formed by the shaft and the bearing has inherent frequency characteristics, so that the problem of critical rotating speed of a rotor is related. Standard specifications for designing and manufacturing a steam turbine, a water pump, a centrifugal compressor and the like all have the specified critical rotation speed avoidance rate requirements so as to avoid resonance. The characteristic of bearing support rigidity is an important ring related to the critical rotation speed of a shafting, so designing a rigidity-adjustable bearing support system is an important way and method for adjusting the critical rotation speed of the shafting. The bearing and the supporting system thereof have smaller influence on the first-order critical rotation speed value of the rotor system under the condition of lighter rotor mass, but have larger influence on the critical rotation speed value of the rotor system under the condition of heavier rotor mass. For example, the rotor weight of a high-power turbine plant can reach several tons, with design speeds of substantially over 3000 rpm, and such rotor operating speeds are often transcritical, known as compliant rotors. The supporting rigidity of the bearing supporting system of the traditional design is fixed and not adjustable, the general rigidity design is higher to bear/restrain the vibration transmitted by the equipment, the rigidity of the bearing (referred to as a sliding bearing) is limited, and the rigidity value is difficult to improve after reaching a certain order of magnitude. Therefore, it can be seen from the basic formula ω= v (K/M) of vibration that the natural frequency (rotor critical rotation speed) decreases with increasing rotor mass, and therefore the first-order critical rotation speed of a rotor of large mass is not high, limited by the slide bearing stiffness value. The design technology of the large-mass flexible rotor is complex, repeated iterative calculation is needed, meanwhile, a unit often needs multiple target working conditions with different rotating speeds to adjust and use, and the conventional design method easily falls into a resonance region. Disclosure of Invention Aiming at the defects in the prior art, the invention solves the technical problem of how to control the critical rotation speed of the rotor by adjusting the rigidity of the bearing support system. In order to achieve the above object, the method for controlling the critical rotation speed of the rotor by adjusting the rigidity of the bearing support system provided by the invention comprises the following steps: Building a bearing support system rigidity model, marking calculated rigidity points as O1, and marking support points at two ends as O2 and O3; collecting a distance a between O1 and O2, and collecting a distance b between O1 and O3; collecting bearing rigidity K2 at O2 and collecting bearing rigidity K3 at O3; Obtaining bearing support rigidity K0 at O1 according to a, b, K2 and K3; Obtaining the rigidity KM1 suffered by the mass M1 at the O1 according to the bearing supporting rigidity K0 at the O1 and the transverse rigidity K1 of the shaft at the O1; From M1 and KM1, the critical rotation speed of the rotor is obtained. By adopting the technical scheme, a bearing support system rigidity model is built, related data and rigidity are acquired, according to the rigidity of a rotor system of rotating equipment, the rigidity mainly comprises the transverse rigidity of a shaft and the bearing support rigidity, the relation between the transverse rigidity and the bearing support rigidity is series rigidity, the rigidity between the bearing and the bearing is parallel rigidity, the rigidity born by the mass of the point can be calculated, the critical rotation speed of the rotor is further obtained, and a basis is provided for regulating the rigidity of the bearing support system to control the critical rotation speed of the rotor. In one embodiment, the bearing support stiffness K0 at O1 is obtained from a, b, K2 and K3, comprising in particular: calculating the bearing support rigidity K0 at O1 through a first formula, wherein the first formula is that 1/K0=(1/K2)b2/(a+b)2+（1/K3）a2/(a+b)2。 By adopting the technical scheme, the rigidity model of the bearing support system is built, the distances a and b and the bearing support rigidity K2 and K3 are collected, the bearing support rigidity K0 at the O1 position is calculated by utilizing the first formula, b