The aerothermal performance of a trailing edge (TE) internal cooling system of a high pressure gas turbine blade was evaluated under stationary and rotating conditions. The investigated geometry, selected capitalizing the experience about industrial collaboration, consists in a 30:1 scaled model reproducing the typical wedge shaped discharge ribbed duct with one row of enlarged pedestals. The airflow pattern inside the device simulates a highly loaded rotor blade cooling scheme with a 90[deg] turning flow from the radial hub inlet to the tangential TE outlet. Six different configurations were tested: two different tip mass flow rates (the first one with a completely closed tip, the second one with the approximately 12.5% of the inlet flow discharged from the tip) and three different surface conditions: the first one consists in the flat plate case and the others in two ribbed cases, with different angular orientation (60 [deg] and -60 [deg] respect to the radial direction). In order to assess rotation effects, a rotating test rig was purposely developed and manufactured. It is composed of a rotating arm holding both the PMMA TE model and the instrumentation devices. A rotary joint ensures the pneumatic connection between the blower and the rotating apparatus, moreover several slip rings are used for both instrumentation power supply and thermocouple connection. A thin Inconel heating foil and wide band Thermo-chromic Liquid Crystals are used to perform steady state heat transfer measurements on the blade suction side. Analyzed flow conditions correspond to Reynolds number near to 20000 in the hub inlet section and angular speed varies to obtain rotational numbers in the range from 0 to 0.3. The orientation of the rotation axis is orthogonal to the heated surface as to resemble a 90deg blade metal angle. Results are reported in terms of detailed heat transfer coefficient 2D maps on the suction side surface as well as in terms of span-wise profiles inside the pedestal ducts. The effects of rotation on the heat transfer coefficient is assessed by comparing with static measurements in the same fluid-dynamic conditions.

HEAT TRANSFER MEASUREMENTS AND EFFECTS OF ROTATION IN A TRAILING EDGE COOLING SYSTEM / Leonardo Bonanni; Carlo Carcasci; Bruno Facchini; Lorenzo Tarchi. - ELETTRONICO. - (2011), pp. 1-12. (Intervento presentato al convegno 66° Congresso Nazionale ATI tenutosi a Rende (Cosenza) nel 5-9 Settembre 2011).

HEAT TRANSFER MEASUREMENTS AND EFFECTS OF ROTATION IN A TRAILING EDGE COOLING SYSTEM

BONANNI, LEONARDO;CARCASCI, CARLO;FACCHINI, BRUNO;TARCHI, LORENZO
2011

Abstract

The aerothermal performance of a trailing edge (TE) internal cooling system of a high pressure gas turbine blade was evaluated under stationary and rotating conditions. The investigated geometry, selected capitalizing the experience about industrial collaboration, consists in a 30:1 scaled model reproducing the typical wedge shaped discharge ribbed duct with one row of enlarged pedestals. The airflow pattern inside the device simulates a highly loaded rotor blade cooling scheme with a 90[deg] turning flow from the radial hub inlet to the tangential TE outlet. Six different configurations were tested: two different tip mass flow rates (the first one with a completely closed tip, the second one with the approximately 12.5% of the inlet flow discharged from the tip) and three different surface conditions: the first one consists in the flat plate case and the others in two ribbed cases, with different angular orientation (60 [deg] and -60 [deg] respect to the radial direction). In order to assess rotation effects, a rotating test rig was purposely developed and manufactured. It is composed of a rotating arm holding both the PMMA TE model and the instrumentation devices. A rotary joint ensures the pneumatic connection between the blower and the rotating apparatus, moreover several slip rings are used for both instrumentation power supply and thermocouple connection. A thin Inconel heating foil and wide band Thermo-chromic Liquid Crystals are used to perform steady state heat transfer measurements on the blade suction side. Analyzed flow conditions correspond to Reynolds number near to 20000 in the hub inlet section and angular speed varies to obtain rotational numbers in the range from 0 to 0.3. The orientation of the rotation axis is orthogonal to the heated surface as to resemble a 90deg blade metal angle. Results are reported in terms of detailed heat transfer coefficient 2D maps on the suction side surface as well as in terms of span-wise profiles inside the pedestal ducts. The effects of rotation on the heat transfer coefficient is assessed by comparing with static measurements in the same fluid-dynamic conditions.
2011
66° Congresso Nazionale ATI
66° Congresso Nazionale ATI
Rende (Cosenza)
5-9 Settembre 2011
Leonardo Bonanni; Carlo Carcasci; Bruno Facchini; Lorenzo Tarchi
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Utilizza questo identificatore per citare o creare un link a questa risorsa: https://hdl.handle.net/2158/628306
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