The main objective of this work is to investigate the effect of windage heating on the micro high-speed rotor-stator cavity.The influences of centrifugal force and spacing on the windage heating are analyzed with and ...The main objective of this work is to investigate the effect of windage heating on the micro high-speed rotor-stator cavity.The influences of centrifugal force and spacing on the windage heating are analyzed with and without the change of gap ratio respectively.The results demonstrate that there is no difference in the flow structure between micro and large-scale rotorstator cavities at the same rotational Reynolds number and gap ratio.However,the windage heating induced by the larger centrifugal force and smaller spacing brings the different heat transfer laws for the micro rotor-stator cavity.The larger centrifugal force weakens the local heat transfer near the rotor periphery.Such influence can be strengthened at higher rotational Reynolds numbers and lower rotor excess temperatures.Besides,the smaller spacing further enhances the windage heating and reduces the average heat transfer especially under the condition of lower gap ratio.The findings of this work contribute to the design of rotor-stator cavity utilized in the micro rotating machinery.展开更多
In order to ensure the safety of engine life limited parts （ELLP） according to airworthiness regulations, a numerical approach integrating one-way fluid structure interaction （FSI） and probabilistic risk assessme...In order to ensure the safety of engine life limited parts （ELLP） according to airworthiness regulations, a numerical approach integrating one-way fluid structure interaction （FSI） and probabilistic risk assessment （PRA） is developed, by which the variation of flow parameters in a rotor-stator cavity on the safety of gas turbine disks is investigated. The results indicate that the flow parameters affect the probability of fracture of a gas turbine disk since they can change the distribution of stress and temperature of the disk. The failure probability of the disk rises with increasing rotation Reynolds number and Chebyshev number, but descends with increasing inlet Reynolds number. In addition, a sampling based sensitivity analysis with finite difference method is conducted to determine the sensitivities of the safety with respect to the flow parameters. The sensitivity estimates show that the rotation Reynolds number is the dominant variable in safety analysis of a rotor-stator cavity among the flow parameters.展开更多
The rotating disk cavity is an important part of the cooling-air system of the aero engine,and it has obviously significance to study the internal flow and heat transfer characteristics of the disc cavity,which will b...The rotating disk cavity is an important part of the cooling-air system of the aero engine,and it has obviously significance to study the internal flow and heat transfer characteristics of the disc cavity,which will be helpful to improve the efficiency of the aero engine.This paper summarizes the existing research results of domestic and overseas.The present work considers the test methods and calculation methods of the flow and heat transfer characteristics of the rotating disc cavity of the aircraft engine.It points out that,the main factors which affect the heat transfer characteristics are the disc chamber speed,the intake volume,the design of the disc cavity pre-rotation/despin structure,and the type of disc cavity system.The influence of these factors on the characteristics of flow heat transfer is summarized.Based on these factors,the disc cavity structure can be optimized and designed,which provides suggestions for reducing the weight of the turbine,improving the thrust-to-weight ratio of the aero engine,and improving the cooling efficiency.展开更多
The rotating disk surface temperature rise due to windage heating effect by numerically modeling the turbulent flow within a rotor-stator cavity which is available with a peripheral shroud and imposed through airflow ...The rotating disk surface temperature rise due to windage heating effect by numerically modeling the turbulent flow within a rotor-stator cavity which is available with a peripheral shroud and imposed through airflow was dealt with.The windage heating may be defined as viscous friction heating caused by relative velocity differences across the boundary layers between the fluid and the rotating disk surface.The kinetic energy dissipation process could transform the rotating shaft power into thermal heating.Commercial finite volume based solver,ANSYS/CFX was employed to numerically simulate this physical process by using the shear stress transport(SST)turbulence model.CFD results include the rotating disk surface temperature axial distribution and tangential velocity distribution of the fluid domain.The velocity difference between the result obtained by particle image velocimetry(PIV)experiments and CFD simulation are within 5%.The adiabatic disk temperature rise can be calculated by the tangential velocity of disk and fluid in large gap ratio and turbulent parameter.CFD temperature distribution results and those estimated via velocity differences are within 10%.展开更多
Rotor-stator cavities are frequently encountered in engineering applications such as gas turbine engines.They are usually subject to an external hot mainstream crossflow which in general is highly swirled under the ef...Rotor-stator cavities are frequently encountered in engineering applications such as gas turbine engines.They are usually subject to an external hot mainstream crossflow which in general is highly swirled under the effect of the nozzle guide vanes.To avoid hot mainstream gas ingress,the cavity is usually purged by a stream of sealing flow.The interactions between the external crossflow,cavity flow,and sealing flow are complicated and involve all scales of turbulent unsteadiness and flow instability which are beyond the resolution of the Reynolds-average approach.To cope with such a complex issue,a wall-modeled large-eddy simulation(WMLES)approach is adopted in this study.In the simulation,a 20°sector model is used and subjected to a uniform pre-swirled external crossflow and a stream of radial sealing flow.It is triggered by a convergent Reynoldsaveraged Navier-Stokes(RANS)result in which the shear stress transport(SST)turbulent model is used.In the WMLES simulation,the Smagoringsky sub-grid scale(SGS)model is applied.A scalar transportation equation is solved to simulate the blending and transportation process in the cavity.The overall flow field characteristics and deviation between RANS and WMLES results are discussed first.Both RANS and WMLES results show a Batchelor flow mode,while distinct deviation is also observed.Deviations in the small-radius region are caused by the insufficiency of the RANS approach in capturing the small-scale vortex structures in the boundary layer while deviations in the large-radius region are caused by the insufficiency of the RANS approach in predicting the external crossflow ingestion.The boundary layer vortex and external ingestion are then discussed in detail,highlighting the related flow instabilities.Finally,the large-flow structures induced by external flow ingress are analyzed using unsteady pressure oscillation signals.展开更多
基金support from the National Natural Science Foundation of China(Grant No.51606003)The authors acknowledge the editors for handling the manuscript and the reviewers for their constructive comments that have significantly improved the manuscript.
文摘The main objective of this work is to investigate the effect of windage heating on the micro high-speed rotor-stator cavity.The influences of centrifugal force and spacing on the windage heating are analyzed with and without the change of gap ratio respectively.The results demonstrate that there is no difference in the flow structure between micro and large-scale rotorstator cavities at the same rotational Reynolds number and gap ratio.However,the windage heating induced by the larger centrifugal force and smaller spacing brings the different heat transfer laws for the micro rotor-stator cavity.The larger centrifugal force weakens the local heat transfer near the rotor periphery.Such influence can be strengthened at higher rotational Reynolds numbers and lower rotor excess temperatures.Besides,the smaller spacing further enhances the windage heating and reduces the average heat transfer especially under the condition of lower gap ratio.The findings of this work contribute to the design of rotor-stator cavity utilized in the micro rotating machinery.
基金Innovation Plan of Aero Engine Complex System Safety by the Ministry of Education Chang Jiang Scholars of China (IRT0905)
文摘In order to ensure the safety of engine life limited parts （ELLP） according to airworthiness regulations, a numerical approach integrating one-way fluid structure interaction （FSI） and probabilistic risk assessment （PRA） is developed, by which the variation of flow parameters in a rotor-stator cavity on the safety of gas turbine disks is investigated. The results indicate that the flow parameters affect the probability of fracture of a gas turbine disk since they can change the distribution of stress and temperature of the disk. The failure probability of the disk rises with increasing rotation Reynolds number and Chebyshev number, but descends with increasing inlet Reynolds number. In addition, a sampling based sensitivity analysis with finite difference method is conducted to determine the sensitivities of the safety with respect to the flow parameters. The sensitivity estimates show that the rotation Reynolds number is the dominant variable in safety analysis of a rotor-stator cavity among the flow parameters.
文摘The rotating disk cavity is an important part of the cooling-air system of the aero engine,and it has obviously significance to study the internal flow and heat transfer characteristics of the disc cavity,which will be helpful to improve the efficiency of the aero engine.This paper summarizes the existing research results of domestic and overseas.The present work considers the test methods and calculation methods of the flow and heat transfer characteristics of the rotating disc cavity of the aircraft engine.It points out that,the main factors which affect the heat transfer characteristics are the disc chamber speed,the intake volume,the design of the disc cavity pre-rotation/despin structure,and the type of disc cavity system.The influence of these factors on the characteristics of flow heat transfer is summarized.Based on these factors,the disc cavity structure can be optimized and designed,which provides suggestions for reducing the weight of the turbine,improving the thrust-to-weight ratio of the aero engine,and improving the cooling efficiency.
文摘The rotating disk surface temperature rise due to windage heating effect by numerically modeling the turbulent flow within a rotor-stator cavity which is available with a peripheral shroud and imposed through airflow was dealt with.The windage heating may be defined as viscous friction heating caused by relative velocity differences across the boundary layers between the fluid and the rotating disk surface.The kinetic energy dissipation process could transform the rotating shaft power into thermal heating.Commercial finite volume based solver,ANSYS/CFX was employed to numerically simulate this physical process by using the shear stress transport(SST)turbulence model.CFD results include the rotating disk surface temperature axial distribution and tangential velocity distribution of the fluid domain.The velocity difference between the result obtained by particle image velocimetry(PIV)experiments and CFD simulation are within 5%.The adiabatic disk temperature rise can be calculated by the tangential velocity of disk and fluid in large gap ratio and turbulent parameter.CFD temperature distribution results and those estimated via velocity differences are within 10%.
基金This work is supported by the National Natural Science Foundation of China(No.5212201273)the National Science and Technology Major Project of China(No.J2019-III-0003)The CFX software and computation resource supplied by Beijing Super Cloud Computing Center,China are acknowledged.
文摘Rotor-stator cavities are frequently encountered in engineering applications such as gas turbine engines.They are usually subject to an external hot mainstream crossflow which in general is highly swirled under the effect of the nozzle guide vanes.To avoid hot mainstream gas ingress,the cavity is usually purged by a stream of sealing flow.The interactions between the external crossflow,cavity flow,and sealing flow are complicated and involve all scales of turbulent unsteadiness and flow instability which are beyond the resolution of the Reynolds-average approach.To cope with such a complex issue,a wall-modeled large-eddy simulation(WMLES)approach is adopted in this study.In the simulation,a 20°sector model is used and subjected to a uniform pre-swirled external crossflow and a stream of radial sealing flow.It is triggered by a convergent Reynoldsaveraged Navier-Stokes(RANS)result in which the shear stress transport(SST)turbulent model is used.In the WMLES simulation,the Smagoringsky sub-grid scale(SGS)model is applied.A scalar transportation equation is solved to simulate the blending and transportation process in the cavity.The overall flow field characteristics and deviation between RANS and WMLES results are discussed first.Both RANS and WMLES results show a Batchelor flow mode,while distinct deviation is also observed.Deviations in the small-radius region are caused by the insufficiency of the RANS approach in capturing the small-scale vortex structures in the boundary layer while deviations in the large-radius region are caused by the insufficiency of the RANS approach in predicting the external crossflow ingestion.The boundary layer vortex and external ingestion are then discussed in detail,highlighting the related flow instabilities.Finally,the large-flow structures induced by external flow ingress are analyzed using unsteady pressure oscillation signals.
