In modern gas turbines, rim seal located between the stator-disc and rotor-disc is used to prevent hot-gas ingestion into the inner stage-gap of high pressure turbine. However, the purge flow supplied to the cavity th...In modern gas turbines, rim seal located between the stator-disc and rotor-disc is used to prevent hot-gas ingestion into the inner stage-gap of high pressure turbine. However, the purge flow supplied to the cavity through the rim seal interacts with the main flow, producing additional aerodynamic loss due to the mixing process which plays a significant role in the formation, development and evolution of downstream secondary flow. In this paper, a set of cascade representative of low aspect ratio turbine is selected to numerically investigate the influence of upstream cavity purge flow on the hub secondary flow structure and aerodynamic loss. Cascade with/without upstream cavity and four different purge mass flow rates are all taken into account in this simulation. Then, a deep insight into the loss mechanism of interaction between purge flow and main flow is gained. The results show that the presence of cavity and purge flow has a significant impact on the main flow which not only changes the vortex structure in both the passage and upstream cavity, but also alters the cascade exit flow angle distribution along the spanwise. Moreover, aerodynamic loss in the cascade rises with the increase of purge flow rate while the sealing effect is also enhanced. Therefore, the effect of upstream cavity purge flow must be considered in the process of turbine aerodynamic design. What is more, it is necessary to minimize the purge flow rate in order to reduce aerodynamic loss on the premise of satisfying cooling requirements.展开更多
In turbine disk cavity,rim seals are fitted between the stator and its adjacent rotor disk.A coolant air injected through the turbine disk cavity to prevent the ingress of mainstream hot gases.The purpose of this pape...In turbine disk cavity,rim seals are fitted between the stator and its adjacent rotor disk.A coolant air injected through the turbine disk cavity to prevent the ingress of mainstream hot gases.The purpose of this paper is to investigate numerically the effect of the upstream purge flow on the aero and thermal performances of a high pressure turbine rotor.The investigations are conducted on a generic rim seal cavity inspired from a realistic turbofan engine.Four purge fractions(PF)equal to 0.2%,0.5%,1.0%and 1.5%of the mainstream are considered.The simulations are done by solving the three-dimensional Reynolds averaged Navier-Stokes and energy transport equations.The results include the effect of the PF on the cooling effectiveness,the sealing effectiveness,the secondary flows with losses and the heat transfer behavior,within the cavity and across the rotor passage.The low PF of 0.2%provided a low cooling effectiveness,a moderate sealing effectiveness and minimum losses.The high PF of 1.5%gave a high cooling effectiveness,a best sealing effectiveness and maximum losses.The medium PF of 1.0%supplied a compromise between the aerodynamic and thermal design needs with good cooling and sealing efficiencies and a tolerable level of losses.展开更多
基金Key Laboratory Foundation (9140C4103091003C) for funding this work
文摘In modern gas turbines, rim seal located between the stator-disc and rotor-disc is used to prevent hot-gas ingestion into the inner stage-gap of high pressure turbine. However, the purge flow supplied to the cavity through the rim seal interacts with the main flow, producing additional aerodynamic loss due to the mixing process which plays a significant role in the formation, development and evolution of downstream secondary flow. In this paper, a set of cascade representative of low aspect ratio turbine is selected to numerically investigate the influence of upstream cavity purge flow on the hub secondary flow structure and aerodynamic loss. Cascade with/without upstream cavity and four different purge mass flow rates are all taken into account in this simulation. Then, a deep insight into the loss mechanism of interaction between purge flow and main flow is gained. The results show that the presence of cavity and purge flow has a significant impact on the main flow which not only changes the vortex structure in both the passage and upstream cavity, but also alters the cascade exit flow angle distribution along the spanwise. Moreover, aerodynamic loss in the cascade rises with the increase of purge flow rate while the sealing effect is also enhanced. Therefore, the effect of upstream cavity purge flow must be considered in the process of turbine aerodynamic design. What is more, it is necessary to minimize the purge flow rate in order to reduce aerodynamic loss on the premise of satisfying cooling requirements.
文摘In turbine disk cavity,rim seals are fitted between the stator and its adjacent rotor disk.A coolant air injected through the turbine disk cavity to prevent the ingress of mainstream hot gases.The purpose of this paper is to investigate numerically the effect of the upstream purge flow on the aero and thermal performances of a high pressure turbine rotor.The investigations are conducted on a generic rim seal cavity inspired from a realistic turbofan engine.Four purge fractions(PF)equal to 0.2%,0.5%,1.0%and 1.5%of the mainstream are considered.The simulations are done by solving the three-dimensional Reynolds averaged Navier-Stokes and energy transport equations.The results include the effect of the PF on the cooling effectiveness,the sealing effectiveness,the secondary flows with losses and the heat transfer behavior,within the cavity and across the rotor passage.The low PF of 0.2%provided a low cooling effectiveness,a moderate sealing effectiveness and minimum losses.The high PF of 1.5%gave a high cooling effectiveness,a best sealing effectiveness and maximum losses.The medium PF of 1.0%supplied a compromise between the aerodynamic and thermal design needs with good cooling and sealing efficiencies and a tolerable level of losses.
