Steam flow excited vibration and dynamic characteristics of seal in different rotor whirling motion

2021 ◽  
Vol 160 ◽  
pp. 107029
Author(s):  
Heyong Si ◽  
Lihua Cao ◽  
Pan Li ◽  
Dongchao Chen
Keyword(s):  
Dynamic Characteristics ◽  
Steam Flow ◽  
Whirling Motion ◽  
Excited Vibration

scholarly journals Dynamic Characteristics and Stability Prediction of Steam Turbine Rotor Based on Mesh Deformation

2020 ◽  
Vol 66 (3) ◽  
pp. 164-174
Author(s):  
Heyong Si ◽  
Lihua Cao ◽  
Pan Li
Keyword(s):  
Dynamic Characteristics ◽  
Rotational Velocity ◽  
Pressure Ratio ◽  
Cross Coupling ◽  
Steam Flow ◽  
Mesh Deformation ◽  
Dynamic Coefficients ◽  
Excited Vibration ◽  
Direct Stiffness ◽  
Rotor Dynamic

In order to study the steam flow excited vibration caused by the eccentricity of a rotor, three-dimensional rotor whirl motion is simulated based on mesh deformation. The mechanism of steam flow excited vibration and its influence on the dynamic characteristics of the rotor are investigated. The results show that the exciting forces change with the displacement of the rotor’s centre. Rotor dynamic coefficients are nonlinear when the rotor whirls pass the mesh deformation. The rotor dynamic coefficients and effective damping increase with the increase of whirl frequency. When the whirl frequency is 24.41 Hz, the rotor dynamic coefficients are strongly affected by rotational velocity. The maximum fluctuations of average direct stiffness, cross-coupling stiffness, direct damping and cross-coupling damping are 8.1 %, 113.2 %, 45.8 %, and 121.0 %, respectively. Effective damping fluctuates greatly when both whirl and rotational frequency are 24.41 Hz. The direct stiffness, direct damping, and effective damping increase with the increase of pressure ratio, which can improve rotor stability. The pressure fluctuation on the rotor’s surface is a primary reason for steam flow excited vibration. The stability margin of the rotor can be estimated precisely via effective damping.

Numerical and Experimental Analyses of Static and Dynamic Characteristics for Partially Helically Grooved Liquid Annular Seals

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
Keisuke Nagai ◽  
Kazuki Koiso ◽  
Satoru Kaneko ◽  
Hiroo Taura ◽  
Yusuke Watanabe
Keyword(s):  
Flow Rate ◽  
Dynamic Characteristics ◽  
Smooth Surface ◽  
Reaction Force ◽  
Leakage Flow ◽  
Dynamic Reaction ◽  
Static And Dynamic Characteristics ◽  
Whirling Motion ◽  
Leakage Flow Rate ◽  
Experimental Analyses

Numerical and experimental analyses of the static and dynamic characteristics of the liquid annular seals with axially partial helical grooves were conducted to investigate the effects of the axial length gal of a helically grooved section in a seal stator. The numerical solution and experimental procedures were applied in the same manner as in previous studies on through-helically grooved seals, wherein the grooves extend across the seal length. The numerical results qualitatively agreed with the experimental results, demonstrating the validity of the numerical analysis. The leakage flow rate Q was lower in the partially helically grooved seals than that of conventional through-helically grooved seals across a small range of rotor spinning velocities. In contrast, the reduction in Q due to the pumping effect caused by the spin of the rotor diminished with the decrease in gal. For a small concentric whirling motion of the rotor, the radial dynamic reaction force Fr and magnitude of variation in the tangential dynamic reaction force Ft with the whirling angular velocity increased with the decrease in gal, and their values approached the corresponding values for the smooth-surface seal. Under the same rotor whirling velocity, the Ft for the partially helically grooved seals became lower than that for the smooth-surface seal (similar to the case for the through-helically grooved seal), although decreasing gal tended to increase Ft. These results suggest that partially helically grooved seals can improve the efficiency and stability margin of the pumps because of the reduction in leakage flow rate and suppression of the rotor forward whirling motion (with large radial and tangential dynamic reaction forces) as compared to conventional through-helically grooved seals.

Experimental Study on Static and Dynamic Characteristics of Liquid Annular Convergent-Tapered Damper Seals With Honeycomb Roughness Pattern

2003 ◽  
Vol 125 (3) ◽  
pp. 592-599 ◽  
Author(s):  
Satoru Kaneko ◽  
Takashi Ikeda ◽  
Takuro Saito ◽  
Shin Ito
Keyword(s):  
Dynamic Characteristics ◽  
Smooth Surface ◽  
Reaction Force ◽  
Static And Dynamic Characteristics ◽  
Damping Coefficients ◽  
Stiffness Coefficients ◽  
Whirling Motion ◽  
Leakage Flow Rate ◽  
Annular Seal ◽  
Honeycomb Pattern

Honeycomb damper seals with convergent-tapered clearance have been proposed to improve static and dynamic characteristics of liquid annular seals employed in pumps. Their characteristics are experimentally investigated and compared to those for a conventional straight (no taper) annular seal with smooth surface and a straight damper seal with identical honeycomb pattern in seal stator. Three convergent-tapered honeycomb damper seals are used in the test, and have different inlet clearance (maximum clearance) and almost the same outlet clearance (minimum clearance). Their outlet clearance is almost the same as the clearance of the straight smooth seal and is slightly smaller than the clearance of the straight damper seal. Experimental results show that the convergent-tapered damper seals as well as the straight damper seal have lower leakage flow rate and cross-coupled stiffness coefficients, and larger main damping coefficients than the straight smooth seal, resulting in larger effective damping coefficients. These results are mainly due to surface roughness in the seal stator such as a honeycomb pattern used in the present analysis. The convergent-tapered damper seals also have larger main stiffness coefficients than the straight smooth and damper seals, which is mainly due to the convergent-tapered clearance and yields larger radial reaction force for a small concentric whirling motion. Consequently, the convergent-tapered damper seals have better seal characteristics than the conventional straight smooth seal and the straight damper seal with the same roughness pattern from the viewpoints of decreasing the leakage and improving the rotor stability capacity.

scholarly journals Fault Diagnosis for Steam-flow Exciting Vibration of Ultra Supercritical 1000 MW Steam Turbine

2015 ◽  
Vol 9 (1) ◽  
pp. 1067-1075
Author(s):  
Chen Li ◽  
Hu Niansu
Keyword(s):  
Load Capacity ◽  
Treatment Plan ◽  
Thermal Power ◽  
Steam Flow ◽  
Power Capacity ◽  
Excited Vibration ◽  
Exciting Vibration ◽  
Reliability Of Operation ◽  
Steam Parameters ◽  
High Load Capacity

With the increase in thermal power capacity, ultra supercritical units have become the mainstream of power industry. At the same time, with the improvement of the steam parameters and the lengthening of shafting, the production of steam flow excited vibration is frequent in the ultra supercritical units, which may seriously affect the reliability of the unit. This paper has taken steam flow excited vibration of a 1000MW turbine as an example in accordance with the experimental and theoretical causes of steam flow excited vibration to solve the problem of steam flow excited vibration by the proposed treatment plan. This can greatly improve the reliability of operation and the units with high load capacity.

Nonlinear Dynamic Analysis of Drill String System for Horizontal Oil Well with Different Positions of Stabilizers

2014 ◽  
Vol 716-717 ◽  
pp. 615-618
Author(s):  
Meng Zhao ◽  
Xiang Zhe Zhu ◽  
Chun Lei Wang
Keyword(s):  
Dynamic Characteristics ◽  
Horizontal Well ◽  
Nonlinear Dynamic Analysis ◽  
Drill String ◽  
Oil Well ◽  
Lateral Vibration ◽  
Element Analysis ◽  
Horizontal Section ◽  
Whirling Motion ◽  
Petroleum Drilling

For the horizontal well of petroleum drilling engineering, the horizontal section of drill string was selected as a research object. Collision and friction between drill string and well wall, displacement response on the drill bit and other boundary conditions were considered in this simulated modeling. By using finite element analysis software ANSYS, the dynamic characteristics of horizontal section of drill string were calculated and discussed. The effect of different positions of stabilizers on the vibration characteristics of drill string were studied specially. The calculated results show that the installation positions of stabilizers have remarkable effects on the dynamic characteristics of drill string. It will change the lateral vibration and whirling motion of drill string remarkably. Furthermore, the reasonably installation of the stabilizers can decrease the amplitudes of lateral vibration and transient torque. Those results may provide some guidance for the vibration analysis of drill string system.

Numerical and Experimental Analyses of Dynamic Characteristics for Liquid Annular Seals With Helical Grooves in Seal Stator

2018 ◽  
Vol 140 (5) ◽  
Author(s):  
K. Nagai ◽  
S. Kaneko ◽  
H. Taura ◽  
Y. Watanabe
Keyword(s):  
Numerical Analysis ◽  
Dynamic Characteristics ◽  
Operating Conditions ◽  
Fluid Film ◽  
Fluid Inertia ◽  
Governing Equations ◽  
Whirling Motion ◽  
Experimental Analyses ◽  
Helical Grooves ◽  
Annular Seals

Numerical and experimental analyses were carried out to investigate the dynamic characteristics of liquid annular seals with helical grooves in the seal stator. In the numerical analysis, the governing equations were the momentum equations with turbulent coefficients and the continuity equation, all averaged across the film thickness and expressed using an oblique coordinate system in which the directions of coordinate axes coincided with the circumferential direction and the direction along the helical grooves. These governing equations were solved numerically to obtain the dynamic characteristics, such as the dynamic fluid-film forces, dynamic coefficients, and whirl-frequency ratio (WFR). The numerical analysis included the effect of both fluid inertia and energy loss at the steps between the helical groove and the land sections. In the experiments, the dynamic fluid-film pressure distributions, which were induced by a small whirling motion of the rotor about the seal center, were measured to obtain the dynamic characteristics. The equivalent numerical results reasonably agree with the experimental results, demonstrating the validity of the numerical analysis. The value of the tangential dynamic fluid force induced by the rotor whirling motion decreased with increasing the helix angle γ. Consequently, the values of the cross-coupled stiffness coefficient and WFR decreased with increasing γ and became negative for large γ. In general, pump rotors rotate with a forward whirling motion under normal operating conditions. Hence, the negative value of WFR for helically grooved seals contributes to rotor stability by suppressing the forward whirling motion of the rotor.

Analysis of whirling motion for the dynamic system of floating ring seal and rotor

2019 ◽  
Vol 233 (8) ◽  
pp. 1221-1235 ◽  
Author(s):  
Peng Xia ◽  
Hui Chen ◽  
Zhansheng Liu ◽  
Wensheng Ma ◽  
Baofeng Yang
Keyword(s):  
Dynamic System ◽  
Perturbation Method ◽  
Dynamic Model ◽  
Nonlinear Model ◽  
Dynamic Characteristics ◽  
Flow Model ◽  
Hydrodynamic Force ◽  
Rotordynamic Coefficients ◽  
Whirling Motion ◽  
Ring Seal

In turbopumps, the dynamic characteristics of the floating ring seal and rotor system are important, especially when the floating ring seal fails to lock up. To investigate the motion of the system with the unlocked floating ring seal, a dynamic model for the whirling system is established in this study. On the basis of the perturbation method, the nonlinear model is simplified into a steady whirling model superimposed with perturbation motion. The transient bulk flow model is improved to calculate the hydrodynamic force in the seal clearance. The results show that the floating ring seal is able to steadily follow the rotor whirling motion and reduce the rotor whirling amplitude when the friction is not enough to lock the seal. The perturbation motion is calculated and proved stable, as the direct rotordynamic coefficients of the floating ring seal are much larger than the cross-coupled coefficients. Further, the effects of the mass and the friction of the floating ring seal, the rotor whirling amplitude and the interaction between the seal and the rotor on the dynamic characteristics of the whirling system are investigated.

Dynamic Characteristics of Fluid Force Induced by Swirling Leakage Flow Between Rotational and Stationary Disks

2012 ◽  
Author(s):  
Takayuki Sugiyama ◽  
Shigehiko Kaneko
Keyword(s):  
Dynamic Characteristics ◽  
Tangential Velocity ◽  
Oscillatory System ◽  
Axial Rotation ◽  
Design Stage ◽  
Leakage Flow ◽  
Force Coefficient ◽  
Fluid Force ◽  
Excited Vibration ◽  
Divergent Channel

Axial self-excited vibration may be induced in a balance piston by fluid with a tangential velocity component that flows into the piston orifices. To avoid such vibration, knowledge of the dynamic characteristics of axial self-excited vibration induced by swirling leakage flow is required at the design stage. In this research, the effect of axial rotation and swirl strength on the added fluid force coefficients is clarified by modeling the piston orifice as the combination of rotational and stationary disks, and deriving the unsteady fluid force generated by swirling leakage flow between the disks. As a result, reduction of the relative velocity in the circumferential direction is shown to destabilize the oscillatory system. In particular, the effect of swirl strength on the fluid force coefficient is found to be larger in the case of the divergent channel than in the case of the parallel flow path.

Sign in / Sign up

Export Citation Format

Share Document