Dan Sun

To alleviate the adverse effects of the flow-field structure caused by interstage sealing structures on the aerodynamic characteristics of compressor cascades, a blade-root through-slot structure was designed in this study. The structure links the pressure surface to the suction surface of the blade. Numerical simulation techniques were utilized to investigate the process. In this process, the through-slot structure enhances corner separation across varying jet positions, jet heights, and jet widths. The results indicate that the high-speed fluid ejected by the through-slot configuration can suppress the accumulation of low-energy fluid at the suction root. It can also alleviate blockages in the cascade passage and reduce the range of separation vortices and recirculation zones on the suction side. Consequently, the flow loss due to separation is reduced. As the through-slot jet progresses from the blade leading edge to the trailing edge, its restraining impact on the low-energy fluid cluster gradually diminishes. This leads to a corresponding reduction in its effect on the total pressure loss. With an increase in the slot height, the restraining impact on corner separation and total pressure loss first rises and then falls. As the through-slot height increases, the suppressive effect on corner separation and loss initially intensifies and then weakens. As the through-slot width increases, the suppressive effect on corner separation and total pressure loss increases steadily. Compared to the original compressor cascade, the through-slot configuration attains peak performance at 25% chord length, with a height of 6% height and a width of 10 mm, reducing the total pressure loss coefficient by 19.22%. Furthermore, as the incoming flow incidence angle enlarges, the enhancement impact of the through-slot configuration on cascade performance initially intensifies and then diminishes. The peak enhancement impact occurs at a 0° incidence angle. At this angle, the configuration can reduce flow loss by 16.72% compared to the original, significantly improving the aerodynamic performance of the high-load compressor cascade.

Accurately predicting the temperature field of turbine blades is of great significance for evaluating the thermal reliability and service life of high-temperature components in aero-engines. However, due to the high computational cost of numerical simulations and the limitations imposed by complex geometric structures and harsh operating environments, experimental measurements can usually only obtain sparse sensor data, making the acquisition of complete temperature distributions still challenging. Therefore, reconstructing the complete temperature field under sparse measurement conditions has become a key research issue in turbine thermal analysis. To address this problem, this paper proposes an attention-enhanced CNN–LSTM framework for reconstructing transient turbine blade temperature fields from sparse data. The model combines the spatial feature extraction capability of Convolutional Neural Networks (CNNs) with the time-series modeling capability of Long Short-Term Memory networks (LSTM). An SE channel attention module is introduced in the CNN feature extraction stage to achieve adaptive recalibration of channel features, and a temporal attention mechanism is incorporated after the LSTM layer to highlight key transient thermal features. A multi-condition temperature field dataset was constructed by conducting Computational Fluid Dynamics (CFD) simulations on low-pressure turbine guide vanes, and the model was experimentally validated through thermal shock tests. The results show that the proposed model can accurately reconstruct the spatial distribution and transient evolution of the turbine blade temperature field under sparse measurement conditions. Under different operating conditions, the predicted temperature fields are highly consistent with the CFD results, with the maximum Reconstruction error remaining below 19 °C. Error distribution analysis indicates that the model has stable Reconstruction performance and good generalization ability.

In this paper, we aim to study the oil–gas two-phase flow characteristics, leakage characteristics, and critical oil sealing characteristics of the bearing cavity sealing system of aero-engine bearings. For this purpose, the unsteady solution models of the conventional bearing cavity sealing system and the graphite with oil-return groove bearing cavity sealing system based on the Euler–Euler two-phase flow method were established. The experimental device for the oil–gas two-phase flow for the bearing cavity was designed and constructed. Thus, the oil–gas two-phase oil sealing characteristics of both systems under different structural and working condition parameters were studied. The results show that the change in the sealing length does not affect the leakage of lubricating oil for the conventional bearing cavity sealing system. It was observed that the higher the rotate speed is, the greater the oil leakage and the greater the critical sealing pressure difference. The graphite with oil-return groove structure can significantly reduce the leakage of lubricating oil and the critical sealing pressure difference. The increase in the length and number of oil-return groove can effectively reduce the leakage of lubricating oil. The width of the oil-return groove has no obvious effect on the sealing and leakage characteristics of the lubricating oil.

This study examines the labyrinth seal disc of an aero-engine, specifically analysing the radial deformation caused by centrifugal force and heat stress during operation. This distortion may lead to discrepancies in the performance attributes of the labyrinth seal and could potentially result in contact between the labyrinth seal tip and neighbouring components. A numerical analytical model incorporating the rotor and stator cavities, along with the labyrinth seal disc structure, has been established. The sealing integrity of a standard labyrinth seal disc’s flow channel is evaluated and studied at different clearances utilising the fluid–solid-thermal coupling method. The findings demonstrate that, after considering radial deformation, a cold gap of 0.5 mm in the conventional labyrinth structure leads to stabilisation of the final hot gap and flow rate, with no occurrence of tooth tip rubbing; however, both the gap value and flow rate show considerable variation relative to the cold state. When the cold gap is 0.3 mm, the labyrinth plate makes contact with the stator wall. To resolve the problem of tooth tip abrasion in the conventional design with a 0.3 mm cold gap, two improved configurations are proposed, and a stability study for each configuration is performed independently. The leakage and temperature rise attributes of the two upgraded configurations are markedly inferior to those of the classic configuration at a cold gap of 0.5 mm. At a cold gap of 0.3 mm, the two improved designs demonstrate no instances of tooth tip rubbing.

Honeycomb bushing wear has a significant effect on the leakage characteristics of the labyrinth seal. In this paper, four kinds of honeycomb bushing labyrinth seals was designed and processed. The leakage characteristics of honeycomb bushing labyrinth seal were studied experimentally under different inlet and outlet pressure ratios and sealing clearance conditions. At the same time, the numerical model of honeycomb bushing labyrinth seals were established, and the influence of honeycomb bushing wear on the flow field characteristics of labyrinth seals was analyzed by numerical simulation. The existing leakage formula was modified by the correction coefficient method. The results show that with the increase in wear depth, the leakage of the honeycomb bushing labyrinth seal increases, and the maximum leakage can be increased by 59.59%. The wear groove weakens the throttling effect of the labyrinth, causing the leakage of the seal to increase. The increase of the depth of the wear groove changes the flow area and the direction of the jet so that the leakage increases slightly. The influence of the wear groove on the leakage characteristics of the honeycomb bushing labyrinth seal is gradually reduced under the condition of large clearance. The theoretical formula of leakage is corrected by the correction coefficient method. The value calculated by the corrected theoretical formula of leakage is in good agreement with the experiment, and the error is within 10%. It meets the practical application of the project.

In order to study the oil–gas two-phase flow characteristics of an aero-engine bearing chamber and improve the scavenge effect of lubricating oil, the two-phase flow solution model of a bearing chamber based on the Euler–Euler method was established. Three improvement schemes were proposed for the ventilation structure and scavenge structure of the bearing chamber. The flow characteristics and scavenge characteristics of a conventional bearing chamber and three improvement schemes under different working conditions were analyzed in depth. The results show that after the conventional bearing chamber ventilation structure is embedded (Embed) and improved, with the increase in the embedding depth, the oil in the cavity is further blocked in the cavity, the amount of oil flowing out from the vent is further reduced, and the scavenge efficiency is further improved. After the slope improvement of the scavenge structure of the conventional bearing chamber, due to the increase in the depth of the oil return groove, the drag effect of the air shear force in the cavity on the oil in the oil return groove is further weakened, and the oil accumulation area on the right side of the scavenge port is further suppressed. The volume fraction of the oil in the cavity is further reduced, and the scavenge efficiency is further improved. The combined improvement scheme (ES) can take into account the advantages of embedding and slope improvement schemes, and further improve the scavenge efficiency. Compared to the conventional bearing chamber, when the oil flow rate is 200 L/h and the speed is 15,000 r/min, the oil return efficiency of the embedded (h = 12 mm), slope (l = 56 mm) and combined improvement schemes are increased by 20.19%, 13.43%, and 37.94%, respectively.

Uneven pressure drops among stages of multistage brush seal (MBS) leads to early failure of single-stage seal units, which directly affects service life of the seal used in aeroengines, gas turbines, and steam turbines. In this paper, influence factors of interstage pressure drop were studied to analyze formation mechanism of the uneven pressure drops. Moreover, an MBS with differentiated structure was presented, and its interstage pressure drops were further investigated. The results showed that the MBS with several same single-stage seal units had uneven pressure drops among stages under high inlet/outlet pressure ratios. In view of remarkably increasing velocity and decreasing pressure in downstream region of bristle pack near rotor surface during flow of airflow, adjustments of structural parameters (i.e., increasing height of backing plate to rotor surface Hb, increasing seal clearance Hg, and decreasing axial width of bristle pack B) could improve the uneven pressure drops among different stages due to increasing outlet air flow area of the stage. The closer pressure drop proportions of different stages to ideal average value indicated increase of Hb had a more effective effect to balance the pressure drops among different stages compared to increase of Hg and decrease of B. An MBS with differentiated structure, in which both Hb and Hg of all the single-stage seal units were increased progressively and B was decreased step by step, showed a good performance to obtain even interstage pressure drops.

To study the influence of taper seal clearance on the static and rotor-dynamic characteristics of hole-pattern damper seals, this paper develops three-dimensional transient computational fluid dynamic methods, which comprise single-frequency and multi-frequency elliptical orbit whirl model, by the transient solution combined with a mesh deformation technique. Through the investigations, it is illustrated that: (1) In the present paper, the leakage rates of convergent-tapered hole-pattern damper seals are less than divergent-tapered hole-pattern damper seals for the same average seal clearance, and the maximum relative variation reaches 16%; (2) Compared with a constant clearance hole-pattern damper seal, the maximum relative variation of the rotor-dynamic coefficients is 1,865% for nine taper degrees in this paper; (3) Convergent-tapered hole-pattern damper seals have smaller reaction forces and effective damping coefficient, larger cross-over frequency, and direct stiffness coefficient, while divergent-tapered damper seals have the opposite effects; (4) Divergent-tapered hole-pattern damper seals alleviate the rotor whirl because of a larger effective damping coefficient when the rotor system has large natural frequency and small eccentricity. Convergent-tapered damper seals provide both sealing and journal bearing capabilities at the same time, and are more advantageous to the stability of the rotor system when rotor eccentricity is the main cause of rotor instability.