## 1 Introduction  
During the design process, the computational simulation phase is extremely important, so that no faults occur during operation, thus avoiding serious losses and accidents. The aeronautical gas turbine studied in this work has already been designed and is under development. With an approximate weight of 650 N, a maximum diameter of 0.350 m, and a maximum length of 1.50 m, that aeronautical gas turbine is capable of producing 5 kN of thrust at the rotational speed of 28,150 rpm [1; 2; 3; 4]. Figure 1a,b illustrate the aeronautical gas turbine studied in this work on the test rig. It is composed of an air inlet duct, a five-stage axial compressor, a direct-flow annular combustion chamber, a single stage turbine disc, and an exhaustion nozzle, in a single shaft configuration. Figure 2a,b show the compressor and turbine discs and Figure 2c shows the whole rotor assembly without bearings.  
Gas turbines operate under rigorous conditions of temperature and stress. High temperatures are necessary to increase thermal efficiency and reduce fuel consumption. However, high temperatures can compromise structural integrity of mechanical components by reducing the yield strength in metallic alloys and/or favoring creep. That is why it is important to calculate the temperature distribution over the main static and rotating components of a gas turbine. The determination of the temperature distribution over the gas turbine components makes it possible to select appropriate metallic alloys to withstand the rigorous operating conditions. However, in some cases there is no appropriate metallic alloy able to meet the design requirements, and a redesign process must be conducted. In order to overcome the material barrier, extensive research and development in new metallic alloys and other materials has been done. The main objective is to be able to use higher and higher temperatures at the turbine disc entry to improve overall efficiency.  
Compressor and turbine discs are critical components that should be carefully analyzed. These components are under high thermal stresses and high centrifugal loads. In spite of the fact that higher temperatures are found on turbine discs, compressor discs can also be potentially dangerous. This happens because aluminum alloys, which are usually used in compressor discs, present a strong reduction in their mechanical properties with temperature increase. In high performance compressors, the last rotor stages are made of high temperature alloys in order to withstand the high thermal and structural effects. In turbine discs, the use of Inconel alloys is a choice in the great majority of cases, since Inconel alloys present superior mechanical properties at elevated temperatures.  
Figure 1: Illustration of the aeronautical gas turbine studied in this work on test rig: (**a**) Perspective view including inlet and exhaustion ducts; (**b**) Side view.  
Figure 2: Rotating assembly of the aeronautical gas turbine with its compressor and turbine discs: (**a**) Compressor discs; (**b**) Turbine disc; (**c**) All rotating assembly.  
The heat transfer analysis presented in this paper simulates the temperature distribution over the main gas turbine components. It also provides the thermal expansion behavior of the static and rotating assemblies. With the increase in temperature in the aeronautical gas turbine there will be a proportional increase in the structural demanding for both rotating and static assemblies in terms of amplitudes of vibration. Furthermore, when considering higher temperatures, damage to the main parts of the aeronautical gas turbine is accelerated as a result of more severe fluid-structure interaction. Thus, structural analyses can be performed taking into account the thermal effects predicted, which makes it possible to assure that problems generated by high temperatures like creep, thermal stresses, reduction in mechanical strength or insufficient clearances do not cause structural collapse or malfunctioning over the studied gas turbine.