Abstract
As the core equipment of the power generation system, a gas turbine is an indispensable energy-converting device in the national industry. The flow inside a high-pressure turbine (HPT) is highly unsteady, which has a great influence on the aerothermal performance and structural strength. To better clarify the flow mechanism and guide the advanced design, the basic flow characteristics of transonic turbines are investigated in the paper by a modified scale-adaptive simulation (SAS) model based on the shear stress transport (SST) turbulence model. The numerical results reveal the formation and development of the secondary flow structures such as wake vortex, pressure wave, shock wave, and the interactions among them. The length and frequency characteristics of wake are in good agreement with the large eddy simulation (LES) and the experimental data. Based on the detailed flow information, the local loss analysis is performed using the entropy generation rate. In summary, the wake vortex-related flow is the main origin of unsteadiness and entropy loss in high-pressure turbine cascade.
Highlights
Due to highly complex geometries and viscous effect, various secondary flows which cover a range of length scales and frequencies are formed in a gas turbine
As a continuation of the above work, in this paper, an in-house computational fluid dynamics (CFD) solver integrated with the improved scale-adaptive simulation (SAS) model is employed to delineate the unsteady phenomena and local loss related to vortex shedding, and the underlying flow mechanisms of transonic high-pressure turbine (HPT) vanes are analyzed in different working conditions
A modified SAS model based on the Menter stress transport (SST)-SAS model was applied to the numerical simulation and flow mechanism analysis of the transonic turbine
Summary
Due to highly complex geometries and viscous effect, various secondary flows which cover a range of length scales and frequencies are formed in a gas turbine. The global hybrid models such as scaleadaptive simulation and delayed detached-eddy simulation have received considerable attentions, especially in engineering practices Because they combine the advantages of RANS and LES methods, the pure LES and DNS are costly to be applied to high Reynolds number flows due to unacceptable CPU requirements [1]. As a continuation of the above work, in this paper, an in-house CFD solver integrated with the improved SAS model is employed to delineate the unsteady phenomena and local loss related to vortex shedding, and the underlying flow mechanisms of transonic HPT vanes are analyzed in different working conditions
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