Heat transfer in leading and trailing edge cooling channels of the gas turbine blade under high rotation numbers

摘要

The gas turbine blade/vane internal cooling is achieved by circulating thecompressed air through the cooling passages inside the turbine blade. Leading edge andtrailing edge of the turbine blade are two critical regions which need to be properlycooled. Leading edge region receives extremely hot mainstream flow and high heattransfer enhancement is required. Trailing edge region usually has narrow shapedgeometry and applicable cooling techniques are restricted. Heat transfer will beinvestigated in the leading edge and trailing edge cooling channels at high rotationnumbers close to the engine condition.Heat transfer and pressure drop has been investigated in an equilateral triangularchannel (Dh=1.83cm) to simulate the cooling channel near the leading edge of the gasturbine blade. Three different rib configurations (45?, inverted 45?, and 90?) were testedat four different Reynolds numbers (10000-40000), each with five different rotationalspeeds (0-400 rpm). By varying the Reynolds numbers (10000-40000) and the rotationalspeeds (0-400 rpm), the rotation number and buoyancy parameter reached in this study were 0-0.58 and 0-2.3, respectively. 45? angled ribs show the highest thermalperformance at stationary condition. 90? ribs have the highest thermal performance at thehighest rotation number of 0.58.Heat transfer coefficients are also experimentally measured in a wedge-shapedcooling channel (Dh =2.22cm, Ac=7.62cm2) to model an internal cooling passage nearthe trailing edge of a gas turbine blade where the coolant discharges through the slot tothe mainstream flow. Tapered ribs are put on the leading and trailing surfaces with anangle of attack of 45?. The ribs are parallel with staggered arrangement on oppositewalls. The inlet Reynolds number of the coolant varies from 10,000 to 40,000 and therotational speeds varies from 0 to 500 rpm. The inlet rotation number is from 0 - 1.0.The local rotation number and buoyancy parameter are determined by the rotationalspeeds and the local Reynolds number at each region. Results show that heat transfer ishigh near the regions where strong slot ejection exists. Both the rotation number andbuoyancy parameter have been correlated to predict the rotational heat transferenhancement.