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Considering the complexity of the gearbox structure, the first six orders are identified by using the single-point excitation and multipoint response modal identification technology, and the modal confidence, namely, the modal identification accuracy is high. Based on the first six orders of the gearbox obtained from the test, a modal finite element calculation method considering both calculation accuracy and calculation efficiency is proposed. Subsequently, the topology optimization method is used to optimize the structure of the gearbox. After optimization, the deformation of the gearbox at different natural frequencies is reduced, which provides a new idea for the optimization design of the gearbox structure.

A novel type of integral damping gear （IDG） is developed and designed to study the influence of different damping liquid viscosity of IDG on the vibration and noise reduction characteristics of the gear transmission system. The IDG damping mechanical model is established, and the effectiveness of IDG control of gear system vibration is analyzed. An experimental platform for the first-order spur gear transmission system is built to compare the vibration at the support of the ordinary spur gear system and the IDG system with different damping liquid viscosity. The results show that IDG can effectively control the vibration of the gear transmission shaft system. In the range of damping fluid viscosity used in this experiment, with the increase of the damping fluid viscosity used in IDG, the vibration of the gear shaft system decreases gradually, and the average vibration reduction amplitude of IDG under the maximum viscosity is more than 50%. At the same time, IDG can effectively reduce the noise of the gear system, and the maximum viscosity can reduce 7.6 dB（A） noise. It is further proved that IDG has excellent vibration and noise reduction characteristics, which ensures the smooth operation of the gear transmission system and provides a new idea for vibration and noise reduction of the gear system.

As an important part of mechanical transmission, gears have become one of the main sources of vibration and noise of mechanical equipment in the application process. In order to reduce and isolate the vibration of the helical gear system, a novel structure of G-type integral squeeze film damper (GISFD) is proposed, and the influence of GISFD on the vibration characteristics of the helical gear is explored. Based on GISFD, an open-type single-stage helical gear test bench is built, and the GISFD's influence experiment on the vibration characteristics of the helical gear system at different speeds is carried out. The experimental results show that GISFD has a good vibration reduction effect on helical gear shafts at different speeds. At 1,200 r/min, the vibration reduction of the main and secondary shaft of helical gear under GISFD can reach up to 59.61%. Meanwhile, GISFD can suppress the vibration of the helical gear meshing frequency and its second frequency, and the vibration reduction can reach up to 85.71%. GISFD also has a good vibration suppression effect on worn helical gears, and the vibration reduction in the horizontal direction of the driving shaft can reach 83.99% at 1 200 r/min.

The Consortium for Top-Down Proteomics (www.topdownproteomics.org) launched the present study to assess the current state of top-down mass spectrometry (TD MS) and middle-down mass spectrometry (MD MS) for characterizing monoclonal antibody (mAb) primary structures, including their modifications. To meet the needs of the rapidly growing therapeutic antibody market, it is important to develop analytical strategies to characterize the heterogeneity of a therapeutic product's primary structure accurately and reproducibly. The major objective of the present study is to determine whether current TD/MD MS technologies and protocols can add value to the more commonly employed bottom-up (BU) approaches with regard to confirming protein integrity, sequencing variable domains, avoiding artifacts, and revealing modifications and their locations. We also aim to gather information on the common TD/MD MS methods and practices in the field. A panel of three mAbs was selected and centrally provided to 20 laboratories worldwide for the analysis: Sigma mAb standard (SiLuLite), NIST mAb standard, and the therapeutic mAb Herceptin (trastuzumab). Various MS instrument platforms and ion dissociation techniques were employed. The present study confirms that TD/MD MS tools are available in laboratories worldwide and provide complementary information to the BU approach that can be crucial for comprehensive mAb characterization. The current limitations, as well as possible solutions to overcome them, are also outlined. A primary limitation revealed by the results of the present study is that the expert knowledge in both experiment and data analysis is indispensable to practice TD/MD MS.

Gear transmission systems are widely used in ship propulsion systems, but, during operations, they produce serious vibration and noise problems, reducing the fatigue life of gears and affecting the performance of ships and the comfort of operators. Taking into account the complex frequencies and vibration components of gear transmission systems, this study conducted wide-band vibration suppression and noise reduction research on a gear transmission system using an integral squeeze film damper (ISFD), providing a novel approach for reducing vibration and noise in gear transmission systems. By conducting a simulation analysis and numerical calculations, the ISFD was analyzed via a static analysis and a dynamic analysis. We developed an experimental platform for reducing vibration and noise in gear transmission systems using sliding bearings, and the experiments were conducted under different speed and load conditions to study the vibration suppression and noise reduction of gears based on the ISFD. The experimental results show that the ISFD has good vibration suppression capabilities for gears at different speeds, with a horizontal vibration reduction of 75.44% and a vertical vibration reduction of 68.48% at 2400 r/min. The ISFD has wide-band vibration suppression capabilities, especially for mesh frequency and twice-mesh frequency, with a vibration reduction of 86.96% or more. Moreover, the ISFD has good vibration suppression capabilities for gears at different load torques, with a reduction of more than 35% in all directions. In addition, the ISFD also has noise reduction capabilities, reducing the gears' noise by 1.92 dB at different speeds. [ABSTRACT FROM AUTHOR]

Aiming at the problems of large leakage and high friction heat generation of the piston ring under high pressure and high speed, based on the previous research on the V-shaped groove piston ring, the research on the design method of the V-shaped groove piston ring is carried out in depth. The numerical analysis is carried out focusing on the number of V-shaped grooves and the depth of the V-shaped grooves of the piston ring. The influence law is verified and analyzed by using a high-pressure and high-speed rotating test bench. The simulation and experimental results show that the leakage of 4 grooves and 8 grooves piston ring is reduced by 14.9 and 28.5%, and the temperature is reduced by 10.9 and 4.7%; When there are 8 V-shaped grooves on the piston ring, the leakage is reduced by 28.5 and 21.7%; when the V-shaped groove depth is 0.04 and 0.08 mm, the temperature is reduced by 4.1%. However, when the V-shaped groove depth is 0.12 mm, the leakage is increased by 2.7% compared with the traditional piston ring. Appropriate groove number and groove depth can realize the coordinated design of low leakage and low friction temperature rise. [ABSTRACT FROM AUTHOR]

In view of the problem that the vibration of the centrifugal impeller of the compressor exceeds the standard when a micro turbojet engine crosses the first-order critical speed, this research proposes a vibration control technology for the engine rotor system based on the new integral squeeze film damper (NISFD) according to the unique structure and assembly characteristics of the rotor bearing seat of the micro turbojet engine. Through numerical analysis and experimental research, the dynamic characteristics of NISFD are analyzed, and the vibration reduction mechanism of NISFD is revealed. The engine test verification based on NISFD is carried out. The results show that NISFD has good damping characteristics, which can improve the bending stress and strain energy distribution of the rotor. The engine test proves that NISFD can well solve the problem of excessive vibration of the engine when passing through the first-order critical speed, greatly reduce the vibration level within the working speed range, and significantly improve the reliability of the engine during operation. It provides a solid theoretical basis for the design of aeroengine, and provides a reference for the practical engineering application of NISFD in aeroengine. [ABSTRACT FROM AUTHOR]

The accumulation of catalyst dust at the honeycomb seal for a long time will lead to the honeycomb seal cell blockage, weaken the seal effect of the honeycomb seal, and directly affect the safe and stable operation of the flue gas turbine. Therefore, a research on the influence of honeycomb cell blockage on the seal leakage characteristics is carried out. The flow field model of honeycomb seal is established, and the influence of cell blockage on the leakage characteristics of honeycomb seal is analyzed. A seal leakage characteristic experiment bench is built, and the numerical simulation results are verified by the experiment bench. Compared with the honeycomb seal without blockage, the leakage of the honeycomb seal with a blockage rate of 25% increases by about 6.5%, while the leakage of the honeycomb seal with a blockage rate of 25% obtained by the experiment increases by about 6.3%. The numerical simulation results are in good agreement with the experimental results. The results of this research provide theoretical support for revealing the seal leakage characteristics of honeycomb seals under blockage faults. [ABSTRACT FROM AUTHOR]

To solve the poor precision and low efficiency of manual grinding de-weight dynamic balance of turbopump rotor, the laser de-weight dynamic balance technology of rotating machines is adopted. Combined with the advantages of laser de-weight, such as, fast processing speed high machining precision and good machined surface quality, the smooth transition of the machined surface was realized by means of hierarchical machining. According to the characteristics of the turbopump rotor structure, the equivalent transformation model for laser de-weight turbopump rotor was built to convert the unbalance into laser processing parameters, which achieve the rapid and accurate de-weight of turbopump rotor. It focuses on solving the repeatedly loading and low accuracy of manual grinding dynamic balance. To verify the effectiveness of the proposed technique, laser de-weight experiments were carried out on two turbopump rotor test pieces. A dynamic balance test bench was set up to measure the rotor residual unbalance at 1800 r/min test speed, which is low dynamic balance. The results show that the machined surface transition was smooth, the residual unbalance was small and the machining efficiency was high. The effect of laser de-weight dynamic balance reached the expectation. It is an universal technology which is not limited to the dynamic balance of turbopump rotor, but also applicable to other rotating machinery.. [ABSTRACT FROM AUTHOR]

Aiming at the problem of frictional heat generation under high pressure and high speed of the piston ring, the V-groove piston ring is proposed. The finite element analysis method is used to compare and analyze the temperature distribution law of the traditional piston ring and V-groove piston ring. The experimental study on the temperature rise of the piston ring seal is carried out by using the high-pressure and high-speed rotating sealing experimental bench. The experimental results are consistent with the simulation results. The results show that when the rotor speed increases by 1000 rpm, the temperature rise of the traditional piston ring increases by 18.4%, the V-groove piston ring increases by 17.2%. For every 0.5 MPa increase in the pressure applied to the piston ring, the temperature rise of the traditional piston ring increases by 9.2%, the V-groove piston ring increases by 5.8%. The same under the working conditions, the temperature rise of the V-groove piston ring is reduced by 21–29% compared with the traditional piston ring, and the leakage of the V-groove piston ring is reduced by 12–19% compared with the traditional piston ring. The synergistic design of low temperature rises and low leakage of the piston ring. [ABSTRACT FROM AUTHOR]

To solve the problems of the nonlinear damping force in the traditional squeeze film damper (SFD), a novel structure of G-type integral squeeze film damper (GISFD) based on ISFD is proposed for the first time. The finite element model and test rig of the ball bearing-rotor system are established to explore the influence of GISFD and ISFD on the dynamic characteristics of the unbalanced rotor system. The results show that both GISFD and ISFD can change the critical speed of the rotor system, reduce the bending strain energy of the shaft, and reduce the bearing dynamic load of the rotor system. Through comparison, it is found that the effect of GISFD is more obvious. The experimental results show that, compared with the unbalanced rotor system without damper, the peak-peak value of amplitude in the rotor system with GISFD and ISFD at 3000 rpm is reduced by 25.53 and 15.81%. The amplitude in the disk at the first-order critical speed is effectively reduced, and the reduction range reach 52.01 and 35.44%, respectively. GISFD has a more significant effect of suppressing unbalanced vibration, and has superior vibration damping performance when compared with ISFD. [ABSTRACT FROM AUTHOR]

As a novel structural damper, the unique structural characteristics of the integral squeeze film damper (ISFD) solve the nonlinear problem of the traditional squeeze film damper (SFD), and it has good linear damping characteristics. In this research, the experimental studies of ISFD vibration reduction performance are carried out for various working conditions of unbalanced rotors. Two ball bearing-rotor system test rigs are built based on ISFD: a rigid rotor test rig and a flexible rotor test rig. When the rotational speed of rigid rotor is 1500 rpm, ISFD can reduce the amplitude of the rotor by 41.79%. Under different unbalance conditions, ISFD can effectively improve the different degrees of unbalanced faults in the rotor system, reduce the amplitude by 43.21%, and reduce the sensitivity of the rotor to unbalance. Under different rotational speed conditions, ISFD can effectively suppress the unbalanced vibration of rigid rotor, and the amplitude can be reduced by 53.51%. In the experiment of the unbalanced response of the flexible rotor, it is found that ISFD can improve the damping of the rotor system, effectively suppress the resonance of the rotor at the critical speed, and the amplitude at the first-order critical speed can be reduced by 31.72%. [ABSTRACT FROM AUTHOR]

In order to solve the problem of excessive vibration of the slurry circulation pipeline at vacuum tower bottom of slurry bed residue hydrogenation unit of a petrochemical enterprise, and to ensure the safe and stable operation of the equipment, a 3D model of this section of pipeline is established by combining the characteristics of the unit and the actual operating conditions of the process system. The finite element analysis software is applied to numerically simulate the pipeline, analyze the main influencing factors of the pipeline vibration, and apply viscous dampers to damp the vibration of this section of pipeline. Through the system simulation, optimization of installation plan, determination of damper installation position and reinforcement method, the theoretical simulation calculation of the final plan shows a maximum vibration reduction of 70.6% for the pipeline. After the implementation of the plan, the actual vibration value on site had a maximum reduction of 89. 14%, and the actual application effect has achieved the expected results, greatly reducing the operational risk of the pipeline. [ABSTRACT FROM AUTHOR]

The Reynolds-averaged Navier–Stokes (RANS) solver was used to calculate, using a test rig to verify the accuracy. The interaction mechanism between different sealed cooling air and gas ingestion at the rotor-stator cavity and chute rim clearance has been investigated. Several groups of representative sealed cooling air flow were selected to explore the cooling efficiency, flow characteristics, tangential and radial velocity ratios in the cavity and the pressure potential field characteristics of trailing edge. The conclusions are obtained: the sealed cooling air flow rate has a significant marginal effect on the sealing effect. The gas ingestion behavior under the small sealed cooling air flow belongs to the disc cavity intrusion, and the intrusion and outflow regions at the of rim clearance are obviously divided into the intrusion characteristic section and the outflow characteristic section. The ingestion behavior under large sealed cooling air flow belongs to clearance ingestion, and the intrusion flow is limited to the chute rim clearance position, which cannot be further penetrated into the cavity. At this time, the clearance area and the cavity area become independent, and the gas ingestion characteristics depend more on the internal flow of the clearance and the vortex structure formed. [ABSTRACT FROM AUTHOR]

Relative high pressure in the rotor–stator (RS) cavity helps to improve its seal effectiveness. However, every 1% increase in the cavity flow results in a decrease of the stage power of turbine by about 0.32% and a decrease in the aerodynamic efficiency by about 0.33%. With rim cavity flow, the pressure distribution in the suction side of rotor blade domain and the turbine flow structure show obvious circumferential differences, which are caused by the interactions between the RS cavity flow and the mainstream. The flow characteristic in the false externally-induced ingress in rim clearance is proposed for the first time to reveal the flow mechanism in the effect of RS rim cavity flow on the turbine. [ABSTRACT FROM AUTHOR]