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ABSTRACT
The effect of impingement jet on heat transfer in a rotating wedge-shaped ribbed trailing edge was experimentally investigated in this study. The inlet Reynolds number varied from 10000 to 61000, and rotation number from 0.06 to 0.16. Four different impingement structures (angle, diameter and number of impingement jet holes) were selected for investigation in non-rotating state, whereas the basic model structure was explored under rotation state. The heat transfer inside the channel and at the slots was analyzed in detail. The results show that the heat transfer at the leading edge of L-after jet region (the impingement surface) is significantly stronger than that of T-after jet region. Variation of impingement structures has altered the jet Reynolds number. Specifically, when the hole diameter narrowed, the jet Reynolds number increased by 30%, and the heat transfer of L-after jet by 10%. As the number of holes increased, the distribution of mass flow was uneven. When trailing edge acted as the impingement target surface, the heat transfer of trailing edge surface was close to that of the leading edge surface. The effect of rotation on heat transfer was concentrated on inlet region and high-radius region. Enhancement of inlet region led to reduction of other positions (especially for high-radius regions).
NomenclatureEnglish symbols
| A | = | Area (m2) |
| Cp | = | Heat capacity at constant pressure (J/(kg·K)) |
| Dh | = | Hydraulic diameter (m) |
| e | = | Rib height (m) |
| h | = | Heat transfer coefficient (W/(m2 ·K)) |
| I | = | Current of heater (A) |
| L | = | Length of the channel (m) |
| = | Mass flow rate (kg/s) | |
| Nu | = | Nusselt number |
| n | = | Rotational speed (rpm) |
| P | = | Heat transfer coefficient measured point in X-direction |
| p | = | Rib pitch (m) |
| Pr | = | Prandtl number |
| r | = | Distance from rotation axis to channel inlet (m) |
| R | = | Resistance of each heater (X) |
| Re | = | Reynolds number |
| Ro | = | Rotation number |
| T | = | Temperature |
| U | = | Mean velocity of coolant (m/s) |
| WP | = | Wetted perimeter |
| X | = | Coordinate direction |
Greek symbols
| α | = | Wall-to-environment heat-loss coefficient (W/K) |
| β | = | Angle from channel symmetrical plane to rotating plane (°) |
| μ | = | Viscosity of coolant (Pa·s) |
| λ | = | Heat conductivity coefficient (W/(m·K)) |
| Ω | = | Rotational speed (rad/s) |
| ρ | = | Density of the coolant (kg/m3) |
Subscripts
| ave | = | Average parameter |
| b | = | Local bulk temperature |
| eff | = | Effective parameter based on total inlet mass flow rate |
| i | = | Number of the measured point in the X direction |
| in | = | Inlet |
| loss | = | Loss |
| net | = | Net |
| s | = | Stationary |
| w | = | Wall |
| x | = | Local parameter |
| 0 | = | Fully-developed turbulent flow in circular pipe with smooth wall |
Acknowledgments
The authors would like to express their acknowledgment to AECC Commercial Aircraft Engine Co., Ltd for the financial support.