A turbine blade made of a metal alloy (k = 17 W/m·K) has a length of 5.3 cm, a perimeter of 11 cm, and a cross-sectional area of 5.13 cm2. The turbine blade is exposed to hot gas from the combustion chamber at 1053°C with a convection heat transfer coefficient of 538 W/m2·K. The base of the turbine blade maintains a constant temperature of 450°C and the tip is adiabatic.

Respuesta :

The base of the turbine blade maintains a constant temperature of 450°C and the tip is adiabatic is 1076.67° C.

Explanation:

The rate of heat transfer for the turbine blade is expressed.

[tex]Q=\sqrt{h P k A}\left(T_{b}-T_{\infty}\right) \tanh (m L)[/tex]

The parameters are calculated.

[tex]m=\sqrt{\frac{h P}{k A}}[/tex]

[tex]=\sqrt{\frac{\left(538 \mathrm{W} / \mathrm{m}^{2} \mathrm{K}\right)(0.11 \mathrm{m})}{(17 \mathrm{W} / \mathrm{m} \cdot \mathrm{K})\left(0.000513 \mathrm{m}^{2}\right)}}[/tex]

m = 82.38

Hence the rate of heat transfer for the turbine blade is

Q = [tex]\sqrt{(538)(0.11)(17)(0.000513)(450-1093)tanh(82.38)(0.053)}[/tex]

Q = -461.758 W

The temperature at the blade tip is calculated.

[tex]\frac{T_{x}-T_{\infty}}{T_{b}-T_{\infty}}[/tex] = [tex]\frac{1}{\cosh (m L)}[/tex]

[tex]\frac{T_{x}-1093^{\circ} \mathrm{C}}{450^{\circ} \mathrm{C}-1093^{\circ} \mathrm{C}}[/tex] = [tex]\frac{1}{\cosh (82.38 \times 0.053)}[/tex]

[tex]\frac{T_{x}-1093^{\circ} \mathrm{C}}{450^{\circ} \mathrm{C}-1093^{\circ} \mathrm{C}}[/tex] = 0.0254

[tex]T_{x}[/tex] = 1076.67° C