End Of Shaft Research Articles

Field Test Study on the Bearing Capacity of Extra-Long PHC Pipe Piles under Dynamic and Static Loads

Pretensioned prestressed high strength concrete (PHC) pipe piles are widely used in various engineering foundations, which have the advantages of high single pile bearing capacity, strong adaptability to geological conditions and high degree of construction mechanization. In order to study the vertical compressive bearing performance and settlement characteristics of ultra-long PHC pipe piles, high strain dynamic detections and static load tests were carried out on four PHC piles with a diameter of 0.9 m on site. It can be seen from the field test that the bearing capacity of the prefabricated pipe piles was time-dependent. By the end of the dynamic test, the bearing capacity of each test pile increased by 27% to 66%. The static load test also verified the rationality of the value of the restitution coefficient. Therefore, the final bearing capacity of the pile foundation can be predicted by using the high strain initial driving results and the restitution coefficient, which can reduce the repeated driving process, effectively save the cost and improve the engineering efficiency. Under 2.1 times the design load, the change range of the pile concrete modulus is from 37.5 GPa to 52 GPa, the change range of the pile side friction resistance is from 0 kPa to 97 kPa and the change range of the pile end to pile bottom load ratio is from 0% to 7.54%. During the test, the shaft friction and end bearing of the lower part of the piles were not fully mobilized. The shaft friction resistance, the end resistance and the movement behavior of the pile top and the end of the piles can provide parameter references for the subsequent design and construction of the piles.

Calculation of joint fits of elastic sleeve-pin couplings with shafts

The causes of defects in the connections of elastic pin-sleeve couplings with shafts are analyzed. It was revealed that such defects as the wear of the mounting holes of the half-coupling and the bearing of the keys and grooves on the shaft and in the holes of the half-coupling are due to the lack of tightness in the shaft-coupling connection. An analysis of the standards for the manufacture of couplings and shaft ends showed that most of the recommended fits would not provide the specified durability of the joint due to the presence of gaps and small interferences, at which there would be a relative movement of the surfaces of the mating parts. A technique is developed for selecting fits for joints of elastic pin-sleeve couplings with shafts to increase their reliability and service life. The technique was tested on the example of calculating the fit of half-couplings on shafts for H 090.40 gearboxes, depending on the method of their assembly. As a result of calculations Ø50H8/v7 and Ø50H8/u8 fits were obtained, each of which differs from that recommended by the standard. Ø50H8/v7 fit has high interference and guarantees no twisting when transmitting torque. It is the most expedient to use the Ø50H8/u8 fit, obtained by assembling by heating the bushing, since it is more stable in the range of tightness with a lower accuracy of shaft processing and, therefore, the cost of shaft processing will be lower. Keywords: elastic pin-sleeve coupling, tightness, fit, limit tightness, fit tolerance, torque. metr@rgau-msha.ru

ANTHROPOMETRICSTUDY OF PROXIMAL END OF DRIED ADULT HUMAN FEMUR: A CROSS SECTIONAL STUDY

Introduction: Femur is the longest and strongest bone of the human body. Its length is associated with a striding gait, its strength with weight and muscular forces. It comprises of an upper end, shaft and lower end. Proximal part of femur includes head, neck, greater and lesser trochanters. Objectives: The present study aimed to record the femoral length and head diameter parameters were carried out which would be of help to the orthopedicians while carrying out surgical repairs around the hip joint especially in fracture of the neck of femur. Material & Methods: A total of 100 North Indian unpaired dry adult human femora (Right-50, Left-50) of unknown sex were studied. Femoral length and Head Diameter of the femur were measured with the help of osteometeric board and vernier caliper and recorded in centimeters. The raw data obtained were statistically analyzed. Range, mean, standard deviation, and standard error of mean were determined. Results: - The mean femoral length was found to 43.93cm (Right- 44.53cm and Left- 43.33cm) with a range of 38.5 – 58.8cm (Right = 38.5 – 58.8cm and Left=38.5 – 51.3cm). The mean femoral head diameter was 39.35mm (Right = 39.86mm and Left =38.84mm) with a range of 20 – 47mm (Right = 20 – 46mm and Left = 32 - 47mm). No significant difference in values of femoral parameters were found in the right and left femur. Conclusion: The overall goal of this study was to generate information that would be useful for geometric modeling of femora and collecting data which could prove useful for the development of prosthetic implants.

Morphofunctional reorganization of hair follicles in C<sub>57</sub>BL/6 mice at different stages of development

The aim of the study was to determine the temporal sequence of structural and functional reorganization of hair follicles in the skin of C57BL/6 mice after anagen induction.Material and methods. 30 male mice of the C57BL/6 inbred line were used for the study. Anagen induction was carried out by depilation of the hair shafts of the skin of the back. Mice were withdrawn from the experiment on the 1st, 5th, 9th, 15th, 19th, 28th days after anagen induction. Skin samples of the depilation area were fixed in buffered neutral formalin and examined using survey microscopy, morphometry, immunohistochemistry, and statistics.Results. The study of the morphological picture from the 1st to the 28th day after anagen induction showed that cyclic changes in the thickness of the dermis, subcutaneous adipose tissue and the structure of hair follicles occur in the skin. On the 1st day after anagen induction the synchronous entry of hair follicles into the anagen stage I was observed: hair follicles were completely in the dermis, had a rounded dermal papilla, above which, towards the epidermis, there was a proliferating follicular epithelium in the form of an expanding and elongating strand . On the 5th day, morphological signs corresponding to the stage of anagen III b were observed: hair follicle bulbs were located in the upper third of the subcutaneous tissue. The dermal papillae looked friable and enlarged, around their upper pole there was a zone of melanogenesis, a hair shaft and an internal root epithelial sheath being formed. The morphological changes on the 9th and 15th days corresponded to the anagen stage VI: the tips of the pigmented hair rods emerged from the funnels of the hair follicles to the surface of the epidermis, the hair follicles were located deep in the subcutaneous fatty tissue, reaching the subcutaneous muscle. The hair follicles had a narrow dermal papilla, a zone of melanogenesis, and the forming hair shafts had regular pigmentation. A pronounced thickening of the dermis and subcutaneous adipose tissue was noted. On the 19th day, the hair follicles were in the catagen VI phase: two-row bag-like structures were observed, forming capsules of the secondary hair germ). They surrounded the keratinized brush-like depigmented proximal ends of the hair shafts. Hair follicles with a rounded dermal papilla were located in the middle of the subcutaneous adipose tissue. The dermal papillae were separated from the capsule of the secondary hair germ by a cord of follicular keratinocytes. Proximal to the dermal papillae, elements of the connective tissue sac were visible. On the 28th day, corresponding to the telogen stage, the hair follicles were located completely in the dermis, had a rounded, dense dermal papilla, which was adjacent to the germinal capsule. On the 19th and 28th days after anagen induction, a decrease in the width of the dermis and subcutaneous fat was noted.Conclusions. Thus, during the cycle of the hair follicle, its stage-by-stage remodeling and the change in the thickness of the dermis and subcutaneous fat, dependent on this process, take place. The following time sequence of the structural and functional reorganization of hair follicles was determined: on the 1st day after depilation, the hair follicles were synchronized in the anagen I stage, on the 5th day – anagen IIIb, on the 9th and 15th days – anagen VI, on Day 19 – catagen VI stage, on day 28 – telogen stage.

Design and Fabrication of Solar Powered Three Ways Grass Cutter

The grass is mowed uniformly using a solar-powered grass cutter. Future power usage will be substantial. With it, lawns at parks, colleges, schools, and other locations are maintained and taken care of. The highly fine and uniform surface appearance of the lawn is easily operated and maintained by untrained individuals. Modern grass-cutting equipment is becoming increasingly widespread. Our daily lives show us how man-made pollution works. Older lawn cutter models had IC engines, which were bad for the environment and increased pollutants. An IC engine-driven cutter is more expensive. Such commonplace machinery needs considerable upkeep. We plan to develop a new type of solar-powered lawn cutter that is more affordable than the one now in use to get past these problems. Solar energy is the term used to describe the heat and light radiations that we receive from the sun. It is among the most widely used and diverse non-conventional renewable energy sources available on a global scale. It is devoid of contaminants, enters the market right away, and has no value. The use of equipment like star panels, which are constructed of electrical phenomenon cells, to produce electricity and power from solar energy. This year, solar system has drawn more attention because of its advantages over other renewable energy sources. The demand for and requests for green energy technology derived from renewable energy sources are increasing. The Solar Grass Cutter is a mechanical device that cuts grass with the usage of electricity. Its body is first constructed from PVC pipe, square shape plywood and caster wheels are then positioned under the body of the square plywood. Then, an inclined fibre plate is set on a body with a solar panel attached to it. That transmits solar energy, which is changed into electrical energy, which is changed into mechanical energy at the end of electric motor shaft, which contain the blade setup to cut the grass.

Development of low-cost self-propelled multi-purpose power unit

The self-propelled multipurpose power unit was developed in the laboratory of Farm Machinery and Power Engineering, JNKVV, Jabalpur for small farmers. The prime mower is powered by a 5hp diesel engine. The V-belt drive is provided for the transmission of power from the engine to the traction wheels. An adjustable accelerator wire is connected to the governor for adjusting the engine speed according to the requirement. The worm gear reduction unit is located at the axle having a speed reduction ratio of 20:1. A telescopic type frame is provided to support the end of the adjustable output shaft with the help of a bearing. The handle is modified to vary the height from 1.0 to 1.3 m from the ground. The additional lug cage wheel is connected to the transport wheel to increase the traction. Noise and Vibration isolators are provided between the engine and chassis to reduce the noise level and vibration. The noise level of the power unit was suitable for 8 working hr. The range of noise with load conditions is 60, 65, 70 (dB) and without load conditions 74, 79, 86 (dB), this limit of noise is under the permissible limit 90db. Vibration range according to optimum rpm 1200, rated rpm 1500 and maximum rpm 1800 so the output range of vibration in Handle 130 μm and chassis 217 μm, Handle 127 μm and chassis 198 μm, Handle 121 μm and chassis 193 μm.

Stochastic propeller force and moment reconstruction at a shaft end based on an improved Kalman filter

Measuring the unsteady hydrodynamic excitation of a marine propeller at a shaft end accurately from multiple directions is crucial for minimizing the unwanted vibration and noise of ships. Due to the synchronous loading of high static thrust and torque, an innovative piezoelectric multicomponent balance embedded into a hollow shaft end is designed. However, complex coupling between the balance and shaft structure is formed. This leads to crosstalk disturbance and a modal dynamic amplification effect on all measuring channels. To overcome this, an improved Kalman filter algorithm based on the subspace modal identification (SMI) method is established, thus allowing us to reconstruct and locate equivalent unsteady excitations accurately in multiple directions with response-only networks. The effectiveness of proposed framework is test on a simulated nonrotating shaft end system with twelve force and three acceleration response channels. The selection of the smoothing delay parameter and whether crosstalk is considered are two main factors that influence the reconstruction accuracy.

Observer-Based, Robust Position Tracking in Two-Mass Drive System

Precise motion control remains one of the most important problems in modern technology. It is especially difficult in the case of two-mass systems with flexible coupling if only the motor position and velocity are measured. We propose a new methodology of control system design in this situation. The concept is founded on a robust observer design, based on a linear matrix inequality (LMI) solution. The observer cooperates with the original nonlinear controller. The presented approach allows us to solve the position tracking problem for a two-mass drive, with unknown parameters, in the presence of disturbances (for instance, nonlinear friction-like torques) acting on both ends of the flexible shaft. Under this set of assumptions, the problem was never solved previously. The closed-loop system stability is investigated, and the uniform ultimate boundedness of state estimation errors and tracking errors is proven using Lyapunov techniques. Numerical properties of the design procedure and characteristic features of the observer, controller, and closed-loop system are demonstrated by several examples.

Implicit Elastoplastic Finite Element Analysis of a Wheel Bearing Shaft Clinching Process Using the Multi-Body Function

An implicit, elastoplastic, finite element method (FEM) with multi-body treatment function was applied to accurately analyze the real-world shaft clinching of a duplex-pair tapered roller (DPTR) wheel-bearing unit (WBU) under minimal assumptions during modeling. The inner races were viewed as elastoplastically deformable and were fitted to the hub shaft before clinching by imposing a thermal load reflecting the mechanical load of press-fitting. The forming roller (i.e., the power source) was considered to be force-prescribed, similar to the approach on real shop floors. The predictions focused on the homogenizing stage, during which the two inner races bear the preload. At this time, local plastic deformation occurred at the end of the hub shaft and in the armpit area and the cavity was either maintained or enlarged. The predicted cavity size in case of force-prescribed forming roller increased, compared with the velocity-prescribed forming roller. The residual stress became axisymmetric and was divided into two parts by the cavity. These findings allow engineers to control the pre-stresses imparted to the inner races of tapered roller bearing assemblies.

Pile length optimization by using shaft friction and end bearing curves developed from instrumented pile load test

Most high-rise buildings or bridges are supported by drilled cast in-situ piles. Construction project often start with pile capacity design, followed by installation of instrumented ultimate test piles to determine pile-soil response under load. A piled foundation is typically designed with consideration of capacity and various safety factors based on the assumption that the pile will not settle beyond the allowable limit. However, many practitioners have neglected the importance of pile settlement analysis and omitted the instrumented ultimate test pile in construction programs. Lack of knowledge on pile-soil response could lead to overdesign or underdesign of the piled foundation system. To address the research gap, this paper describes the current practice where the pile capacity and optimization analysis is carried out based on SPT-N value correlated to the ultimate load test result. The optimized pile length is then analyzed using another pile optimization approach (T-z method) that applies the nonlinear pile load response curves for shaft friction (t-z curve) and end bearing (q-z curve) derived from the actual test result. Comparative results show that the computed pile head settlement is in good agreement with the measured pile load test result with approximately 86% accuracy. Further optimization can be performed on the working piles by using the T-z method. Additionally, the construction-induced variability, particularly the pile base response in optimization, is also examined. The optimization has economic and environmental benefits as fewer construction materials are needed to ensure the safe performance of the piled foundation.

Static and Rotordynamic Characteristics for Supercritical Carbon Dioxide Spiral Groove Dry Gas Seal With the Tilted Seal Ring

Abstract Supercritical carbon dioxide (SCO2) Brayton cycle has been widely used as a substitute for traditional steam cycles. As one of the key components of power-dense turbomachines, dry gas seal (DGS) has been considered one of the most suitable dynamic seal options due to its superior sealing performance. In this paper, considering the installation errors and external disturbances of the shaft end seal in a 14 MW supercritical carbon dioxide turbine, a comprehensive numerical study was conducted on the seal static and rotordynamic characteristics for four dry gas seal designs with different coning displacements. To account for the real gas effect of SCO2, a table lookup program was used to obtain the physics properties of CO2 under supercritical conditions based on the database of the National Institute of Standards and Technology (NIST). A frequency-dependent rotordynamic coefficients stiffness damping model (KC model) for SCO2 DGS and the mesh deformation technique were adapted to analyze the rotordynamic performance of the designed DGS. Steady-state numerical results of leakage rate, opening force, and steady film stiffness were analyzed and compared under four coning displacements. Transient numerical results of rotordynamic force coefficients were analyzed and studied under four coning displacement ratios and 10 vibration frequencies. Results show that the increase in coning displacement causes a 20% rise in leakage rate and a 2.4% increase in opening force. The tilted seal ring results in a maximum 30%–84% variation of the dynamic stiffness and greatly influences the damping coefficient. From a comprehensive view, the tilt of the seal rings brings undesired influences on both the static and rotor dynamic performance of SCO2 DGS. The distortion of the seal rings due to installation errors and other disturbances should be avoided as far as possible in SCO2 DGSs.

Comparison of two cable configurations in 3D printed steerable instruments for minimally invasive surgery.

In laparoscopy, a small incision size improves the surgical outcome but increases at the same time the rigidity of the instrument, with consequent impairment of the surgeon's maneuverability. Such reduction introduces new challenges, such as the loss of wrist articulation or the impossibility of overcoming obstacles. A possible approach is using multi-steerable cable-driven instruments fully mechanical actuated, which allow great maneuverability while keeping the wound small. In this work, we compared the usability of the two most promising cable configurations in 3D printed multi-steerable instruments: a parallel configuration with all cables running straight from the steerable shaft to the handle; and a multi configuration with straight cables in combination with helical cables. Twelve participants were divided into two groups and asked to orient the instrument shaft and randomly hit six targets following the instructions in a laparoscopic simulator. Each participant carried out four trials (two trials for each instrument) with 12 runs per trial. The average task performance time showed a significant decrease over the first trial for both configurations. The decrease was 48% for the parallel and 41% for the multi configuration. Improvement of task performance times reached a plateau in the second trial with both instruments. The participants filled out a TLX questionnaire after each trial. The questionnaire showed a lower burden score for the parallel compared to multi configuration (23% VS 30%). Even though the task performance time for both configurations was comparable, a final questionnaire showed that 10 out of 12 participants preferred the parallel configuration due to a more intuitive hand movement and the possibility of individually orienting the distal end of the steerable shaft.

Nonlinear dynamic characteristics of full-ceramic motorized spindle considering axial transfer of unbalanced magnetic pull

Full-ceramic motorized spindle is suitable for high-grade CNC machine tool due to its high stiffness and wear resistance, while axial transfer of unbalanced magnetic pull (UMP) caused by reverse magnetic characteristic leads to random vibration at the shaft end. In order to investigate the nonlinear dynamics of full-ceramic motorized spindles under the influence of reverse magnetic, a five-degree-of-freedom dynamic model of bearing-rotor system considering the axial transfer of UMP is constructed. The improved transfer matrix method is proposed to establish the axial transfer model of UMP and the vibration mode of the shaft is obtained. The dynamic characteristics of the bearing-rotor system are analyzed considering the effect of UMP. The magnetic field density and vibration characteristics of the motorized spindle system is studied, and the full-ceramic motorized spindle shaft influence of UMP axial transfer, the vibration of the rotor tends to decrease from inward to outward, while the shaft end vibration also tends to increase gradually with the increase of rotation speed and eccentricity value. The results show that the vibration of ceramic shaft end is 55.4% weaker than that of metal shaft end. It can be seen that under the action of the diamagnetic property, UMP transfer occurs on the ceramic shaft, which reduces the vibration. The experiments show that the average error between the calculated value and the experimental result is 8.5% at the operating speed, which verifies the accuracy of the model developed in this paper.

Oil Injection Cooling Design for the IPMSM Applied in Electric Vehicles

In recent years, the power, torque, speed, and other performance of interior permanent magnet synchronous motor (IPMSM) for electric vehicles have improved. The temperature rise is an important factor limiting the performance of the motors. In this article, a novel hollow shaft oil injection cooling structure is proposed. The cooling oil is passed in from one end of the hollow shaft and enters the permanent magnet cavity through the radial oil channel. The centrifugal force generated by the rotation of the rotor causes the oil to be sprayed from the oil injection holes on the end caps at both ends of the rotor, and the winding ends and the stator are directly cooled, which reduces the internal temperature of the motor. The Taguchi method is used to analyze the influence of the novel hollow shaft oil injection cooling structure on the average temperature of the winding and the difference in the injection flow rate at both ends of the motor. Considering various operating conditions, the optimization scheme of the cooling structure is determined. Finally, the reliability of the structure is verified by stress calculation and modal analysis.

Design & development of X-ray Solar Monitor (XSM) filter wheel drive mechanism with self hold down feature for chandrayaan-2 orbiter

Onboard Chandrayaan-2 Orbiter, an X-ray Solar Monitor (XSM) instrument was flown for the measurement of intensity of solar X-rays within energy band of 1–15 keV. To achieve this, an active filter wheel drive mechanism is used to control the energy of the solar flares falling onto the detector by flipping the filter wheel. During normal flares, the filter wheel is steered to open position whereas during very large solar flares, a beryllium filter is positioned below the detector to reduce the incident solar energy. An in-built flare detection logic operates the mechanism in real-time when the threshold value of solar flares is crossed. The mechanism also has an additional calibration source which regularly calibrates the instrument.The filter wheel drive mechanism is developed as a compact, miniaturized system without requiring any hold-down thereby reducing the mass and design complications. The self-balanced filter wheel is designed by the ingenious usage of dead weights such that center of gravity of the wheel passes through the rotation axis. Together with the back-driving torque of the motor, the tendency of the wheel to jitter during launch is reduced, thus avoiding a separate hold down mechanism. An additional gripping force is ensured between the filter wheel and the motor shaft by using a grub screw. One end of the filter wheel shaft is supported at the base plate through a DU bush to reduce friction during filter wheel’s rotation and the other end is connected to the motor shaft. A novel Optical Sensor based wheel position feedback system is also developed for the position indication during pre and post dynamic tests.In this paper, the design details of the XSM Filter wheel mechanism along with its analysis and hardware performance evaluation during theintegrated tests with the Chandrayaan-2 Orbiter spacecraft is presented.

A control system for MR damper-based suspension of front-loaded washing machines featuring magnetic induction coils and phase-lead compensator

This paper studies a semi-active control system for magneto-rheological (MR) damper-based suspension of front-loaded washing machines. In this system, a permanent magnet is fastened to the shaft end of a shear-mode MR damper and an induction coil is wound directly on the slots of damper housing. Vibration of the washing machine tube leads to the relative reciprocal movement between the magnet and induction coil, which results in an induction voltage. The induced voltage is then served as an input signal to control the damping force of the MR damper. Because of the MR fluid hysteresis, a phase-lead compensator and an amplifier are employed in the controller of the MR damper. After the controller design, simulations and experiments are performed to evaluate the control system effectiveness. From the experimental results, performance characteristics of the proposed control system are discussed and compared with those of constant current and uncontrolled states.

Analysis of Typical Faults of Electric Corrosion of Shaft End Bearings of Metro Traction Motors

Analysis of Typical Faults of Electric Corrosion of Shaft End Bearings of Metro Traction Motors

Analysis of Surface Pressure Pulsation Characteristics of Centrifugal Pump Magnetic Liquid Sealing Film

In order to discuss the surface pressure pulsation characteristics of the magnetic-fluid sealing membrane of centrifugal pump, this paper studies the surface pressure pulsation characteristics of the shaft end sealing membrane under different flow operating conditions of centrifugal pump based on the combination of numerical calculation and experimental verification. The results show that the pressure value on the surface of the magnetic-fluid sealing film decreases with the increase of the flow rate of the centrifugal pump, and the pressure on the surface of the magnetic-fluid sealing film has periodic pulsation, and the period is the time required for a single blade to sweep the volute separating tongue. In one rotation cycle of the runner, the number of reciprocating movements of the magnetic-hydraulic sealing film is the same as the number of blades of the runner. The main reason for the pressure pulsation is that the impeller periodically sweeps the fixed surface of the centrifugal pump.

DETERMINATION OF THE DYNAMIC LOAD CAPACITY OF ROLLING BEARINGS BASED ON THE RATED TORQUE OF THE ELECTRIC MACHINE

The purpose of the article is to describe the method of calculating the dynamic load capacity of the most loaded bearing of an electric machine at the stage of electromagnetic calculation. The proposed method allows to initially determine the dimensions of such parts of an electric machine as bearings and bearing shields. The article considers the calculation of electromagnetic and mechanical parameters of an electric machine on the basis of the machine constant. The transition from the machine constant to the mechanical parameters of the bearing is carried out through the plot of radial loads (reactions) acting on the bearings. The dependences of the length of the shaft end on the permissible torque of the electric machine in accordance with GOST are given for different types of load, different strength and hardness of the shaft material. This technique connects the mechanical and electromagnetic parameters of the machine, allows to perform elements of mechanical calculation at the early stages of development. To simplify the calculation method, some relative geometric parameters are introduced, depending on the type and series or model of the electric machine. The load capacity of the most loaded bearing of the magneto-electric motor 11DVM160 for driving oil pumping machines is calculated. The initial data for the calculation were information from the design documentation, the results of computer modeling of the magnetic field, as well as test results. As a result of the calculation, the value of the dynamic load capacity of the most loaded bearing corresponding to the calculated mechanical load is obtained. In practice, the inverse problem may be relevant – determining the electromagnetic moment and power of the designed electric machine according to the bearing parameters limited by the specified initial dimensions of the machine.

Rotordynamic Characteristics of a Novel Labyrinth Seal With Swirl Brakes at Seal Entrance and Cavity

Abstract Annular gas seals used in turbomachinery are key elements to ensure a high machine efficiency, due to their effect on the leakage flow. As the most common type of annular gas seals, labyrinth seal is widely used as end and center balance drum, interstage, shaft end, and impeller eye seals. However, labyrinth seals have been confirmed to be a major source of destabilizing forces resulting in rotordynamic instability problems. The destabilizing cross-coupling forces, the major mechanism of inducing an instability vibration, are related to swirl velocity in labyrinth seal cavity. Installing swirl brake devices at the seal entrance is efficient to improve the seal stability by suppressing the inlet preswirl velocity. The swirl velocity downstream inlet swirl brakes can be reduced obviously, and it is usually less than the linear velocity of the rotor surface; then, the swirl velocity in seal cavity increases from inlet to outlet as a result of the viscous effect of rotating surface. In this article, to improve the rotordynamic performance of the labyrinth seal, a novel labyrinth seal (design 3), which possesses inlet swirl brakes at the seal entrance and swirl-reversal brakes in the fourth cavity, was designed. The effect of the swirl-reversal brakes on the seal rotordynamic characteristics was numerically investigated at two preswirl velocities and two rotational speeds. A detailed comparison was conducted for the rotordynamic characteristics of this novel labyrinth seal with those of a no-brake configuration (design 1) and an inlet swirl brakes configuration (design 2). The transient computational fluid dynamics (CFD) method based on the multifrequency elliptical whirling orbit model was used to predict frequency-dependent rotordynamic coefficients for these three seal configurations. The accuracy and availability of the present transient numerical method were demonstrated based on the experimental data. In general, for all three seal designs, the rotational speed and the inlet preswirl velocity have a significant effect on the cross-coupling stiffness and effective damping, but a weak influence on the direct stiffness and direct damping, where the effect of the inlet preswirl velocity is more remarkable. For the low inlet preswirl velocity w = 10 m/s case, compared to the original seal design 2, the magnitude of the negative cross-coupling stiffness shows an obvious increase (by ∼314% and ∼218% for the n = 6 krpm and n = 9 krpm case, respectively) for design 3. Compared to the seal design 1 with no swirl brakes, the effective damping increases by ∼33% for design 2 and by ∼130% for design 3 at the rotational speed of 6 krpm. At the high inlet preswirl velocity of w = 106 m/s, the labyrinth seals with no swirl brake (design 1) and with only inlet swirl brake (design 2) both produce the destabilizing positive cross-coupling stiffness and a crossover frequency (175 Hz for the seal design 1, 28 Hz for the seal design 2) below which the effective damping is negative for the n = 9 krpm case; however, design 3 still possesses the stabilizing negative cross-coupling stiffness (below 240 Hz) and the positive effective damping throughout whole frequency range for the n = 9 krpm case. The present novel labyrinth seal (design 3) produces the largest effective damping, followed by the seal design 2 and then the seal Design 1, for all rotational speed and inlet preswirl cases. Therefore, the novel labyrinth seal (design 3) possesses better rotordynamic characteristics than other two seals.