Search Results (8)

High-performance aeroengine design is an important component of modern industry, and advanced sealing technology is a key technology to meet the engine fuel consumption rate, thrust-to-weight ratio, pollutant emission, durability, and lifetime. Reducing the internal airflow leakage of the engine through a sealing technology can improve the performance and efficiency of the engine. In this paper, the typical sealing technology for an aeroengine is introduced in more detail, including the structural characteristics and use limitations of the labyrinth seal, brush seal, honeycomb seal, gas film face seal, and cylindrical gas film seal. It focuses on the development history, typical structure type, working principle, basic technology research method, steady-state performance, dynamic characteristics, multi-physical field coupling, structural deformation, experimental testing, processing technology. Finally, it summarizes the problems and future development trends of the current application of the cylindrical gas film seal in aeroengines, and points out that the seal performance test and evaluation based on advanced composite sensor technology and the innovative design of the seal based on new material, a new principle, and a new structure will be the new research direction. Full article

In this study, the effects of several geometry factors (fin front angle, clearance, number of fins, and honeycomb cell diameter and depth) on the mass flow function of solid and honeycomb land were studied experimentally. The fin front angle considered in the experiment ranged from 60 to 90 degrees, the number of fins was varied between two and three, and the diameter and depth of the honeycomb cell ranged from 1.33 to 4.00 times and 8.08 to 13.08 times the thickness of the fin tip, respectively. The experimental results showed that the mass flow function decreased as the number of fins increased for the solid land labyrinth seal, and the mass flow function increased as the clearance increased. A fin front angle of 60 degrees was found to have the minimum mass flow function. For the honeycomb land labyrinth seal, the mass flow function decreased as the number of fins increased, and the effect of the cell depth was shown to be insignificant compared to the effect of the cell diameter. The effects of cell diameter and cell depth on the mass flow function depended on the conditions of other variables. In addition, the correlation equations of the mass flow functions of the solid land and honeycomb land labyrinth seals are presented based on the experimental results, which represent the effects of the fin front angle, clearance, pressure ratio, and diameter and depth of the honeycomb cell. The correlation equation for the solid land labyrinth seal had an $r^2$ value of 0.9822, while the correlation equation for honeycomb land had an $r^2$ value of 0.9621. Full article

The rotary seal is a key component of the aero engine. Under actual working conditions, most rotary seals always operate in an eccentric state (caused by installation errors), and when a large eccentricity occurs, it may lead to a large amount of gas leakage, resulting in a decrease in aero engine efficiency, which ultimately affects the reliability and life of the aero engine. Therefore, the effect of installation error on the rotary seal of the aero engine was studied in this research. The flow field numerical models of the honeycomb seal, labyrinth seal, and hybrid labyrinth–honeycomb seal were established, the effects of the honeycomb seal, labyrinth seal, and hybrid labyrinth–honeycomb seal on leakage were numerically analyzed, the sealing mechanisms of three types of seals were revealed, and the effect of radial eccentricity on the leakage of three types of seals was also studied. Additionally, the high-pressure and high-speed rotary seal experiment bench was improved, the effect of eccentricity on the leakage characteristics of the honeycomb seal, labyrinth seal, and hybrid labyrinth–honeycomb seal was studied using the improved experiment bench, and the leakage characteristics of the three types of seals were compared under the same condition. The experimental results are consistent with the numerical simulation results; the honeycomb seal is the least sensitive to eccentricity, and its sealing performance is the best. The research results in this paper reveal the seal mechanisms of the honeycomb seal, labyrinth seal, and hybrid labyrinth–honeycomb seal and demonstrate the effect law of eccentricity regarding the leakage characteristics of these three types of seals. The results of this research can provide theoretical support for aero engine efficiency improvement. Full article

The labyrinth-honeycomb seals have been widely used in aero-engine. However, radial cracks appear on labyrinth seal fins of shrouded turbine blade in use. To clarify the rubbing mode of radial crack initiation, a high-speed rubbing test bench was designed. The effects of five rubbing modes on crack initiation were studied. Through the test, it is found that cracks would be formed at the junction of the fin tip and side of the labyrinth seal fins under all five modes. When two successive rubbing modes are different, the temperature of the last rubbing can be lower than that of it alone rubbing, and simultaneous radial and axial rubbing can inhibit each other. Radial rubbing mainly affects the initiation of cracks on fin tip, while axial rubbing mainly affects the initiation of cracks on the side. Moreover, the rubbing temperature is mainly affected by radial force. Full article

Labyrinth-honeycomb seals are a state-of-the-art sealing technology commonly used in aero-engine interstage seal. The undesirable severe rub between the seal fins and the honeycomb due to the clearance change may induce the cracking of the seal fins. A pervious study investigated the wear of the seal fins at different radial incursion rates. However, due to the axial thrust and mounting clearance, the axial rub between the seal fins and the honeycomb may occur. Hence, this paper focuses on the influence of the axial rub added in the radial rub on the wear of the seal fins. The rub tests results, including rubbing forces and temperature, wear rate, worn morphology, cross-sectional morphology and energy dispersive spectroscopy results, are presented and discussed. Overall, the participation of the axial rub leads to higher rubbing forces, temperature, and wear rate. The tribo-layer on the seal fin is thicker and the cracks are more obvious at high axial incursion rate. These phenomena indicate the axial rub has a negative influence on the wear of the seal fins and should be avoided. Full article

Labyrinth seals as a noncontact sealing technology are widely used in aero-engine. To improve the efficiency of the aero-engine, the clearance between the rotor and stator must be as small as possible. However, the change of the clearance between the rotor and stator because of thermal expansion, vibration, mechanical loading may lead to undesirable high-speed rub, which will lead to the cracking of the seal fins. This paper focuses on the wear of the seal fin after the rub and presents the rubbing tests between seal fins and the metal honeycomb under rubbing speed of 380 m/s and incursion rates between 20 and 180 μm/s, with an incursion depth of 1500 μm and a temperature of 350 °C. The rubbing force and temperature were recorded, and the seal fins were checked by SEM and EDS. The results show that the wear mechanism of seal fins changed from oxidation wear and adhesive wear to delamination wear and then to metal wear with the increasing incursion rate. The axial cracks appeared on the worn surface of the seal fins due to the cracking of tribo-layers under periodic thermomechanical stress. The wear mechanism of the seal fin also has a great influence on the rubbing force and temperature. Full article

The labyrinth seals are devices commonly used in turbomachinery to reduce hot gas leakages through engine clearances, which adversely affect the gas turbine performance. For this reason, in the last decades, many in-depth analyses and optimization studies were carried out on this topic using experimental, analytical and numerical approaches. In this work, an innovative rhomboidal pattern is presented, obtained through Computational Fluid Dynamics (CFD) simulations, which is more dissipative than commonly used honeycomb cells. The experiments, performed using a Test Article that reproduces a stage and the next stator of a real low-pressure turbine suitably scaled, allowed to validate the numerical results in a situation that closely approximates the real one of use. The results obtained show that the leakages flow fraction of the total mass flow rate that bypasses the blade, which is 29.4% using a honeycomb pattern, is reduced to 27% with rhomboidal cells. The experimental results also made it possible to verify that the new pattern also behaves well from a thermal point of view, giving rise to temperature differences with respect to the honeycomb of less than 1%. Full article

Labyrinth seals are a state-of-the-art sealing technology to prevent and control leakage flows at rotor–stator interfaces in turbomachinery. Higher pressure ratios and the economical use of cooling air require small clearances, which lead to potential rubbing events. The use of honeycomb liners allows for minimal leakage by tolerating rub events to a certain extent. A previous study within an EU project investigated the complex contact conditions of honeycomb liners, with the idealized contact of a seal fin and a single parallel metal foil representing the honeycomb double foil section. In the present work, the results for the slanted foil position are shown and compared to the previous results. The variation of rub velocity, incursion speed, incursion rate, and seal geometry in a test rig allows for the identification of the influence on contact forces, temperatures, and wear. For the slanted position, significantly lower friction temperatures are observed, leading to a higher ratio of abrasive wear. Overall, the rub test results demonstrate strong interactions between the contact forces, friction temperatures, and wear. Full article