In-service Very-High-Cycle-Fatigue(VHCF)regime of compressor vane and turbine rotor blades of the Al-based alloy VD-17and superalloy GS6K,respectively,was considered.Surface crack origination occurred at the lifetime ...In-service Very-High-Cycle-Fatigue(VHCF)regime of compressor vane and turbine rotor blades of the Al-based alloy VD-17and superalloy GS6K,respectively,was considered.Surface crack origination occurred at the lifetime more than 1500 hours for vanes and after 550 hours for turbine blades.Performed fractographic investigations have shown that subsurface crack origination in vanes took place inspite of corrosion pittings on the blade surface.This material behavior reflected lifetime limit that was reached by the criterion VHCF.In superalloy GS6K subsurface fatigue cracking took place with the appearance of flat facet.This phenomenon was discussed and compared with specimens cracking of the same superalloy but prepared by the powder technology.In turbine blades VHCF regime appeared because of resonance of blades under the influenced gas stream.Both cases of compressor-vanes and turbine blades in-service cracking were discussed with crack growth period and stress equivalent estimations.Recommendations to continue aircrafts airworthiness were made for in-service blades.展开更多
This paper describes the numerical investigations of flow and heat transfer in an unshrouded turbine rotor blade of a heavy duty gas turbine with four tip configurations. By comparing the calculated contours of heat t...This paper describes the numerical investigations of flow and heat transfer in an unshrouded turbine rotor blade of a heavy duty gas turbine with four tip configurations. By comparing the calculated contours of heat transfer coefficients on the flat tip of the HP turbine rotor blade in the GE-E3 aircraft engine with the corresponding ex- perimental data, the K：-o~ turbulence model was chosen for the present numerical simulations. The inlet and outlet boundary conditions for the turbine rotor blade are specified as the real gas turbine, which were obtained from the 3D full stage simulations. The rotor blade and the hub endwall are rotary and the casing is stationary. The influ- ences of tip configurations on the tip leakage flow and blade tip heat transfer were discussed. It＇s showed that the different tip configurations changed the leakage flow patterns and the pressure distributions on the suction surface near the blade tip. Compared with the flat tip, the total pressure loss caused by the leakage flow was decreased for the full squealer tip and pressure side squealer tip, while increased for the suction side squealer tip. The suction side squealer tip results in the lowest averaged heat transfer coefficient on the blade tip compared to the other tip configurations.展开更多
In this paper, a time-dependant calculation of flow in a lobe pump is presented. Calculations are performed using the arbitrary Lagrangean Eulerean (ALE) method. A grid manipulator is needed to move the nodes between ...In this paper, a time-dependant calculation of flow in a lobe pump is presented. Calculations are performed using the arbitrary Lagrangean Eulerean (ALE) method. A grid manipulator is needed to move the nodes between time steps. The used grid manipulator is based on the pseudo-force idea. This means that each node is fictitiously connected with its 8 neighbours via fictitious springs. The equilibrium of the resulting pseudo spring forces defines the altered position of the nodes. The grid manipulator was coupled with a commercial flow solver and the whole was tested on the flow through a three-lobe lobe pump. Results were obtained for a rotational speed of 460 rpm and incompressible silicon oil as fluid.展开更多
The aerodynamic and centrifugal loads acting on the rotating blade make the blade configuration deformed comparing to its shape at rest. Accurate prediction of the running blade configuration plays a significant role ...The aerodynamic and centrifugal loads acting on the rotating blade make the blade configuration deformed comparing to its shape at rest. Accurate prediction of the running blade configuration plays a significant role in examining and analyzing turbomachinery performance. Considering nonlinear stiffness and loads, a reconstruction method is presented to address transformation of a rotating blade from cold to hot state. When calculating blade deformations, the blade stiffness and load conditions are updated simultaneously as blade shape varies. The reconstruction procedure is iterated till a converged hot blade shape is obtained. This method has been employed to determine the operating blade shapes of a test rotor blade and the Stage 37 rotor blade. The calculated results are compared with the experiments. The results show that the proposed method used for blade operating shape prediction is effective. The studies also show that this method can improve precision of finite element analysis and aerodynamic performance analysis.展开更多
文摘In-service Very-High-Cycle-Fatigue(VHCF)regime of compressor vane and turbine rotor blades of the Al-based alloy VD-17and superalloy GS6K,respectively,was considered.Surface crack origination occurred at the lifetime more than 1500 hours for vanes and after 550 hours for turbine blades.Performed fractographic investigations have shown that subsurface crack origination in vanes took place inspite of corrosion pittings on the blade surface.This material behavior reflected lifetime limit that was reached by the criterion VHCF.In superalloy GS6K subsurface fatigue cracking took place with the appearance of flat facet.This phenomenon was discussed and compared with specimens cracking of the same superalloy but prepared by the powder technology.In turbine blades VHCF regime appeared because of resonance of blades under the influenced gas stream.Both cases of compressor-vanes and turbine blades in-service cracking were discussed with crack growth period and stress equivalent estimations.Recommendations to continue aircrafts airworthiness were made for in-service blades.
基金supported by the National 973 Program of China through grant number 2007CB210108
文摘This paper describes the numerical investigations of flow and heat transfer in an unshrouded turbine rotor blade of a heavy duty gas turbine with four tip configurations. By comparing the calculated contours of heat transfer coefficients on the flat tip of the HP turbine rotor blade in the GE-E3 aircraft engine with the corresponding ex- perimental data, the K：-o~ turbulence model was chosen for the present numerical simulations. The inlet and outlet boundary conditions for the turbine rotor blade are specified as the real gas turbine, which were obtained from the 3D full stage simulations. The rotor blade and the hub endwall are rotary and the casing is stationary. The influ- ences of tip configurations on the tip leakage flow and blade tip heat transfer were discussed. It＇s showed that the different tip configurations changed the leakage flow patterns and the pressure distributions on the suction surface near the blade tip. Compared with the flat tip, the total pressure loss caused by the leakage flow was decreased for the full squealer tip and pressure side squealer tip, while increased for the suction side squealer tip. The suction side squealer tip results in the lowest averaged heat transfer coefficient on the blade tip compared to the other tip configurations.
文摘In this paper, a time-dependant calculation of flow in a lobe pump is presented. Calculations are performed using the arbitrary Lagrangean Eulerean (ALE) method. A grid manipulator is needed to move the nodes between time steps. The used grid manipulator is based on the pseudo-force idea. This means that each node is fictitiously connected with its 8 neighbours via fictitious springs. The equilibrium of the resulting pseudo spring forces defines the altered position of the nodes. The grid manipulator was coupled with a commercial flow solver and the whole was tested on the flow through a three-lobe lobe pump. Results were obtained for a rotational speed of 460 rpm and incompressible silicon oil as fluid.
基金supported by National Natural Science Foundation of China,Grant No.51606023 and 51436002Natural Science Foundation of Liaoning Province,Grant No.2015020130Fundamental Research Funds for the Central Universities,Grant No.3132017015
文摘The aerodynamic and centrifugal loads acting on the rotating blade make the blade configuration deformed comparing to its shape at rest. Accurate prediction of the running blade configuration plays a significant role in examining and analyzing turbomachinery performance. Considering nonlinear stiffness and loads, a reconstruction method is presented to address transformation of a rotating blade from cold to hot state. When calculating blade deformations, the blade stiffness and load conditions are updated simultaneously as blade shape varies. The reconstruction procedure is iterated till a converged hot blade shape is obtained. This method has been employed to determine the operating blade shapes of a test rotor blade and the Stage 37 rotor blade. The calculated results are compared with the experiments. The results show that the proposed method used for blade operating shape prediction is effective. The studies also show that this method can improve precision of finite element analysis and aerodynamic performance analysis.
