Abstract:Engine development requires accurate estimates of the heat loads. Estimates of the convective heat fluxes are particularly vital to assess the thermomechanical integrity of the turbomachinery components. This paper reports an experimental heat transfer research in a one and a half turbine stage, composed of a high-pressure turbine and a low-pressure vane. Measurements were performed in a compression tube facility at the von Karman Institute, able to reproduce engine representative Reynolds and Mach numbers. Do… Show more
“…Recently, Pinilla et al investigated the effects of the adiabatic temperature on the heat load of the blades of a gas turbine [21]. Although the airfoil heat exchanger surfaces are rigorously nonadiabatic, the air tempera ture in a boundary layer of a high-speed compressible airflow on a solid surface is close to the adiabatic air temperature.…”
Section: Fig 5 Control Volumes For Inverse Heat Transfer Methods Basementioning
A light and compact heat exchange system was realized using two air-to-refrigerant airfoil heat exchangers and a recirculated heat transport refrigerant. Its heat transfer performance was experimentally investigated. Carbon dioxide or water was used as a refrigerant up to a pressure of 30 MPa. Heat transfer coefficients on the outer air-contact and inner refrigerant-contact surfaces were calculated using an inverse heat transfer method. Correlations were developed for the Nusselt numbers of carbon dioxide and water on the inner refrigerant-contact surface. Furthermore, we proposed a method to evaluate a correction factor corresponding to the thermal resistance of the airfoil heat exchanger.
“…Recently, Pinilla et al investigated the effects of the adiabatic temperature on the heat load of the blades of a gas turbine [21]. Although the airfoil heat exchanger surfaces are rigorously nonadiabatic, the air tempera ture in a boundary layer of a high-speed compressible airflow on a solid surface is close to the adiabatic air temperature.…”
Section: Fig 5 Control Volumes For Inverse Heat Transfer Methods Basementioning
A light and compact heat exchange system was realized using two air-to-refrigerant airfoil heat exchangers and a recirculated heat transport refrigerant. Its heat transfer performance was experimentally investigated. Carbon dioxide or water was used as a refrigerant up to a pressure of 30 MPa. Heat transfer coefficients on the outer air-contact and inner refrigerant-contact surfaces were calculated using an inverse heat transfer method. Correlations were developed for the Nusselt numbers of carbon dioxide and water on the inner refrigerant-contact surface. Furthermore, we proposed a method to evaluate a correction factor corresponding to the thermal resistance of the airfoil heat exchanger.
“…For a few selected geometries, the same geometry was investigated at two different wall temperatures; the entire cavity was set isothermal at 1133K, and then 1300K. The adiabatic convective heat transfer was then computed following the approach described by Pinilla et al [24]. Assuming a linear trend of the heat flux as a function of the wall temperature, the Nusselt number was computed using equations ( 8) and (9).…”
Section: Nusselt Number Comparison With Pipe Flowmentioning
Recent progress in additive manufacturing has enabled opportunities to explore novel stator rim geometries which can be implemented to improve cooling strategies in turbomachinery. This paper presents a simplified stationary geometry optimization strategy to produce enhanced stator-rotor cavity sealing and highlights main driving mechanisms.
The stator and rotor rims were designed using a design strategy based on inspiration from the meandering of rivers. A minimum thickness of 2mm was maintained throughout the cavity to ensure a practical implementation. The computational domain comprised of the stator outlet, hub disk leakage cavity, and rotor platform was meshed using NUMECA Int. package, Hexpress. The numerical analysis required 3D Unsteady Reynolds Average Navier-Stokes to replicate vorticial structures using Ansys Fluent. The operating conditions were representative of engine-like conditions, exploring a wide range of massflow ratios from 1 to 3%. The optimization yielded designs that provide 30% reduction in rear platform temperature while minimizing coolant massflow. The applicability of the design was compared against 3D sector in both stationary and in rotation.
“…Moreover, the thin film-instrumented plate can be heated by electric heaters, thus allowing measurements at different wall temperatures. 23 These measurements, in turn, can be used to calculate the adiabatic wall temperature and, in conjunction with the heat flux measurements, the Stanton number, which can be used as a further gauge of the boundary layer state.…”
This paper presents the design and the results of the qualification test campaign of a multiple-Mach-number supersonic wind tunnel designed for induced boundary-layer transition. Its characteristics, function, and instrumentation are described. The range of Mach numbers successfully span is presented along with the measured intensities of freestream fluctuations. All the measurement techniques implemented in the test campaigns after the qualification are introduced, and some results shown and commented to highlight their potentialities.
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