https://orcid.org/0000-0003-1925-6447
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ABSTRACT
The paper presents the effects of the leakage flow from the inter-platform gap on the migration of hot streak in a first stage turbine by three-dimensional unsteady Reynolds-Averaged Navier-Stokes simulations. Five circumferential positions of the hot streak are considered. The comparisons between the results with/without slot leakage show significant differences. The leakage changes the hot streak in the vane passage significantly and it protects the vane suction surface trailing from the hot gas. The leakage also changes the secondary flow and results in forming a new couple of vortices in the vane passage. In general, rotor passage, the hot gas usually gathers in the rotor hub and the pressure surface. In the present study, the leakage coolant from upstream slot is entrained to the unsteady rotor secondary flows and transported toward the rotor hub and pressure surface effectively. The cooling effect is related to the relative circumferential positions between the hot streaks and slot. When the hot streak is positioned at the slot suction side, the time-averaged temperature reduction on the blade leading edge can be more than twice of that for the hot streak at the slot pressure side.
Nomenclature
| AV | = | Attached vortex |
| BR | = | Blowing ratio |
| CG | = | Cold gas |
| Cax | = | Axial rotor chord from the rotor leading edge |
| DV | = | Detached vortex |
| HPT | = | High pressure turbine |
| HS | = | Hot streak |
| HG | = | Hot gas |
| M | = | million |
| N | = | Time step number |
| NGV | = | Nozzle guide vane |
| P | = | Pressure, Pa |
| PS | = | Pressure side |
| PV | = | Passage vortex |
| RPLE | = | Relative pitch to leading edge of vane1 |
| SS | = | Suction side |
| SST | = | Shear stress transport |
| T | = | Temperature, K |
| Tu | = | Turbulence intensity, dimensionless |
| v | = | Velocity, m/s |
| y+ | = | Non-dimensional distance from the wall |
Greek symbols
| ρ | = | Density, kg/m3 |
| Δp | = | Arc length between the realistic slot and the assumptive slot closest to vane pressure side |
| Δs | = | Arc length between the realistic slot and the assumptive one closest to vane suction side |
Subscripts
| 1 | = | Turbine inlet |
| 2 | = | Turbine outlet |
| 3 | = | Coolant inlet |
| hs | = | Hot streak |
Superscripts
| * | = | Stagnation condition |
Additional information
Funding
Notes on contributors
Kang He
Kang He is a Master student at Nanjing University of Aeronautics and Astronautics, Nanjing, China, under the supervision of Prof. Junkui Mao and Prof. Xingsi Han. He received his Bachelor Degree in Flight Vehicle Propulsion Engineering in 2015 from Nanjing University of Aeronautics and Astronautics. He is currently working on hot streak and cooling technology in the turbine cascade.
Junkui Mao
Junkui Mao is a Professor of thermal science of aero-engines at Nanjing University of Aeronautics and Astronautics, Nanjing, China. He received his PhD degree from Nanjing University of Aeronautics and Astronautics in 2003. His main research interests include thermal management and high efficient cooling technology in aero-engines, thermal analysis of secondary air system, tip clearance active control, and numerical simulation. He has published more than 50 journal papers.
Xingsi Han
Xingsi Han is a Professor at Nanjing University of Aeronautics and Astronautics, Nanjing, China. He received his PhD degree from University of Science and Technology of China in 2009. He mainly works on high-fidelity simulation of complex thermal fluids, including cooling process, turbulent combustion, complex turbulent flow, and flow control. He has published more than 40 journal and conference papers.
Tian Yao
Tian Yao is a Master student at Nanjing University of Aeronautics and Astronautics, Nanjing, PR China, under the supervision of Prof. Junkui Mao and Prof. Xingsi Han. She received her Bachelor Degree in Flight Vehicle Propulsion Engineering in 2015 from Nanjing University of Aeronautics and Astronautics. She is currently working on numerical simulation of convection heat transfer.