Full exam for Heat Transfer and Thermal Analysis in the Aerospace Engineering degree programme at Politecnico di Milano. The document covers: Heat T ransfer and Thermal Analysis - A.Y. 2014/15 - Date 2014/07/22 Surname: Name: ID number: Signature: Part A 1. Sketch ( in a qualitatively accurate way ) some curves of the blackbody emissive power as a function of temperature and wavelength. 2. Write the definitions of the
Full exam for Heat Transfer and Thermal Analysis in the Aerospace Engineering degree programme at Politecnico di Milano. The document covers: Heat T ransfer and Thermal Analysis - A.Y. 2014/15 - Date 2014/07/22 Surname: Name: ID number: Signature: Part A 1. Sketch ( in a qualitatively accurate way ) some curves of the blackbody emissive power as a function of temperature and wavelength. 2. Write the definitions of the
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Heat T ransfer and Thermal Analysis - A.Y. 2014/15 - Date 2014/07/22 Surname: Name: ID number: Signature: Part A 1. Sketch ( in a qualitatively accurate way ) some curves of the blackbody emissive power as a function of temperature and wavelength. 2. Write the definitions of the Nusselt and Biot dimensionless groups, and comment the difference between the two. 3. Write and comment a commonly used rule to determine the Nu value for mixed convection as a function of the Nu values for forced and natural convections. 4. Write the system of equations describing the “energy analysis” for a parallel flow, duct-in-duct heat exchanger. 5. Write the continuity equation for a compressible fluid. 6. Write the finite difference approximations for the first and second derivatives of temperature with respect to a spatial direction using the basic centered form. 7. Put the following materials/substances in correct descending order of thermal conductivity: water, copper, diamond, iron, air, stainless steel. Heat T ransfer and Thermal Analysis - A.Y. 2014/15 - Date 2014/07/22 - Part B Question 1 (up to 10 points) Starting from the energy conservation principle for a closed system and describing the assumptions you make, derive an equation that describes the temperature evolution as a function of time for a small, convex, highly conductive solid body, subject to a single convective exchange with a surrounding fluid for the two cases: 1. a constant and uniform heat source ˙U ′′′ [W/m3] is present within the body; 2. no heat source is present within the body. Analyze and comment the resulting equations. Exercise 1 (up to 10 points) In a homogeneous and isotropic full sphere, made of copper and having radius Rc = 20 mm, a constant and uniform heat source ˙U ′′′ = 10 6 W/m3 is present. Such sphere…
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