Turbine blades mounted to a rotating disc in a gas turbine engine are exposed to a gas stream that is at T = 1300°C and maintains a convection coefficient of h = 300 W/m²-K over the blade. The blades, which are fabricated from Inconel, k 20 W/m-K, have a length of L = 50 mm. The blade profile has a uniform cross-sectional area of A = 6x 10-4 m² and a perimeter of P = 110 mm. A proposed blade-cooling scheme, which involves routing air through the supporting disc, is able to maintain the base of each blade at a temperature of T, = 300°C. (a) If the maximum allowable blade temperature is 1050°C and the blade tip may be assumed to be adiabatic, is the proposed cooling scheme satisfactory? (b) For the proposed cooling scheme, what is the rate at which heat is transferred from each blade to the coolant, W? 9b = i W Gas stream To, h Air coolant Blade tip -Rotating disk

Turbine blades mounted to a rotating disc in a gas turbine engine are exposed to a gas stream that is at T = 1300°C and maintains a convection coefficient of h = 300 W/m²-K over the blade. The blades, which are fabricated from Inconel, k 20 W/m-K, have a length of L = 50 mm. The blade profile has a uniform cross-sectional area of A = 6x 10-4 m² and a perimeter of P = 110 mm. A proposed blade-cooling scheme, which involves routing air through the supporting disc, is able to maintain the base of each blade at a temperature of T, = 300°C. (a) If the maximum allowable blade temperature is 1050°C and the blade tip may be assumed to be adiabatic, is the proposed cooling scheme satisfactory? (b) For the proposed cooling scheme, what is the rate at which heat is transferred from each blade to the coolant, W? 9b = i W Gas stream To, h Air coolant Blade tip -Rotating disk

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)

8th Edition

ISBN:9781305387102

Author:Kreith, Frank; Manglik, Raj M.

Publisher:Kreith, Frank; Manglik, Raj M.

Chapter6: Forced Convection Over Exterior Surfaces

Section: Chapter Questions

Problem 6.36P

See similar textbooks

Similar questions

A horizontal pipe having a surface temperature of 67 °C and diameter of 20 cm is buried at a depth of 1 m in the earth at a location where k = 1.8 W/m-°C. The earth surface temperature is 15 °C. Calculate the shape factor if the pipe length is 10 m.
A 5.0-cm-diameter cylinder is heated to a temperature of 200°C, and air at 30 °C forced across it at a velocity of 50 m/s (h = 180 W/m2 K). If the surface emissivity is 0.7, calculate the total heat loss per unit length if the walls of the enclosing room are at 10 °C. Comment on your calculation.
A 5.0-cm-diameter cylinder is heated to a temperature of 200 oC, and air at 30 oC forced across it at a velocity of 50 m/s (h = 180 W/m2K). If the surface emissivity is 0.7, calculate the total heat loss per unit length if the walls of the enclosing room are at 10 oC. Comment on your calculation. COMPLETE SOLUTION
‏The nose section of the rocket is made up of a 6 mm thick stainless steel plate (p = 7800 kg/m°, c = 460 J/kg°C, k = 55 W/m°C). It is held initially at a uniform temperature of " T = 47°C. When the rocket enters the denser layers of the atmosphere at a very high velocity the effective temperature of the air surrounding the nose region attains the value 2150 °C; the surface convective heat transfer coefficient is estimated as 3395 W/m?°C. If the maximum metal temperature is not to exceed 1100°C, determine: (i) Maximum permissible time in these surroundings. (i) Inside surface temperature under these conditions.
Flue gases from an incinerator are released to atmosphere using a stack that is 0.6 m in diameter and 10.0 m high. The outer surface of the stack is at 40°C and the surrounding air is at 10°C. Determine the rate of heat transfer from the stack assuming (a) there is no wind and (b) the stack is exposed to 20 km/h winds.
Calculate the heat losses per unit length in a horizontal tube with an outside diameter of 15 cm, if its surface is kept at 400 K AND the surrounding air has a temperature of 300 K and a pressure of 1 bar.The properties of air at a pressure of 1 bar and a film temperature of 350 K are: In this case, v = 20.76 x 10-6 m2/s , α = 0.2983 x 10-4 m2/s, k = 0.03003 W/mK, Pr = 0.697, β = 2.86 x 10-3 K-1
A 50-cm-diameter pipeline in the Arctic carries hot oil at 30◦C and is exposed to a surrounding temperature of −20◦C. A special powder insulation 5 cm thick surrounds the pipe and has a thermal conductivity of 7 mW/m · ◦C. The convection heat-transfer coefficient on the outside of the pipe is 9 W/m2 · ◦C. Estimate the energy loss from the pipe per meter of length. (Please give step-by-step solution)
A 50-cm diameter pipeline in the Arctic carries hot oil where the outer surface is maintained at 30 °C and is exposed to a surrounding temperature of -17 °C. The convection heat-transfer coefficient on the outside of the pipe is 9 W/m2 °C. Estimate the energy loss from the pipe per meter of length.
Water at a temperature of 25oC flows parallel over a flat plate with free-stream velocity of 2 m/s. The plate surface temperature is uniform at 86oC. Calculate: a) Thermal boundary layer thickness at x = 8 cm from leading edge; b) Local heat flux on x = 8 cm from leading edge; c) Total heat transfer rate in the area of plate L = 8 cm from the leading edge and width w = 10 cm.
....A journal bearing is to be used for a centrifugal pump where the shaft diameter is 50 mm and the bearing length is 80 mm. The ambient and bearing surface temperatures are 20°C and 45°C, respectively. Which of the following is the heat dissipated by the bearing if the heat dissipation coefficient is 280 W/m2-°C? Group of answer choices 56 W 14 W 73 W 28 W
Explain, motorcycle engine is either considered as free or forced convection. Justify your answer
Fins, or extended surfaces, commonly are used in a variety of engineering applications to enhance cooling. Common examples include a motorcycle engine head, a lawn mower engine head, extended surfaces used in electronic equipment, and finned tube heat exchangers in room heating and cooling applications. Consider aluminum fins of a rectangular profile, which are used to remove heat from a surface whose temperature is100° C . The temperature of the ambient air is 20° C. We are interested in determining how the temperature of the fin varies along its length and plotting this temperature variation. For long fins, the temperaturedistribution along the fin is given by