In modern gas turbines,the High Pressure Turbine(HPT)is exposed to an extreme thermal environment due to the burned gases leaving the combustor.The burned gases are characterized by flow and temperature distortions th...In modern gas turbines,the High Pressure Turbine(HPT)is exposed to an extreme thermal environment due to the burned gases leaving the combustor.The burned gases are characterized by flow and temperature distortions that effect the aerodynamics and heat transfer of the turbine.The purpose of this paper is to investigate numerically the effect of the intensity of the swirling flow combined with the temperature non-uniformity‘‘Hot-Streak"(H-S)on the aerothermal performances of a HPT Nozzle Guide Vane(NGV).The investigations are conducted on the solid untwisted NGV annular cascade developed in NASA Lewis Research Center.Four swirl intensities(|S_(n)|=0,0.1,0.25 and 0.5),two swirl orientations(positive and negative)and two hot-streaks(rounded and radial)at the NGV inlet are considered.The simulations are done by solving the Reynolds Averaged Navier-Stokes(RANS)equations using ANSYS-CFX software.The results show that the H-S with swirl undergoes twisting following the orientation of the swirl.The H-S twist is aggressive under positive swirl compared to the negative swirl case.The inlet swirl generates a new secondary flow structure,so called Swirl Vortex(SV),which induces more aerodynamic losses.The aerodynamic efficiency under negative swirl found to be higher than that under positive swirl.The maximum temperature on the vane surface is controlled by the radial transport of the SV towards the endwalls.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
文摘In modern gas turbines,the High Pressure Turbine(HPT)is exposed to an extreme thermal environment due to the burned gases leaving the combustor.The burned gases are characterized by flow and temperature distortions that effect the aerodynamics and heat transfer of the turbine.The purpose of this paper is to investigate numerically the effect of the intensity of the swirling flow combined with the temperature non-uniformity‘‘Hot-Streak"(H-S)on the aerothermal performances of a HPT Nozzle Guide Vane(NGV).The investigations are conducted on the solid untwisted NGV annular cascade developed in NASA Lewis Research Center.Four swirl intensities(|S_(n)|=0,0.1,0.25 and 0.5),two swirl orientations(positive and negative)and two hot-streaks(rounded and radial)at the NGV inlet are considered.The simulations are done by solving the Reynolds Averaged Navier-Stokes(RANS)equations using ANSYS-CFX software.The results show that the H-S with swirl undergoes twisting following the orientation of the swirl.The H-S twist is aggressive under positive swirl compared to the negative swirl case.The inlet swirl generates a new secondary flow structure,so called Swirl Vortex(SV),which induces more aerodynamic losses.The aerodynamic efficiency under negative swirl found to be higher than that under positive swirl.The maximum temperature on the vane surface is controlled by the radial transport of the SV towards the endwalls.
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.
