In this study, the performance characteristic of a high-speed cooling turbine is investigated using numerical simulation. Cooling turbine is a radial flow reaction turbine with an induction generator mounted on the same shaft. In this project, the cooling turbine is the most important part of aircraft air conditioning system consisting of a radial flow turbine and a centrifugal fan. The objective of this project is simulation of fluid flow in the turbine and fan and also obtaining the cooling turbine performance curve. This project involves modeling of turbine and fan using the SolidWorks, Catia and ANSYS CFX softwares. At first, the turbine and fan rotor geometries are modeled, and then are transferred to Turbo Grid for grid generation. Also, the turbine and fan casing are transferred to CFXmesh for grid generation. Finally, the numerical simulation of fluid flow through the turbine and fan is done using the CFX solver. Boundary conditions for turbine and fan are defined at two steps. At the first one, boundary conditions are defined to obtain the performance characteristic map of the turbine and fan under specific laboratory conditions. The results show the flow is chocked at the turbine rotor outlet. Maximum efficiency of the turbine is equal to %62 at rotational speed of 27,000 rpm and mass flow rate of 0.174 kg/s. Also, a high swirling flow at the turbine rotor outlet causes a high reverse flow at the diffuser outlet. Moreover, the results of fan show the fan pressure ratio in most cases is less than one and the maximum efficiency of the fan rotor is equal to %63 at rotational speed of 50,000 rpm and mass flow rate of 0.3 kg/s. At all cases, the flow separation occurs on the suction surface. Also, flow distortion, incidence and mixing phenomenon occur inside the fan casing. At the second part of this project, boundary conditions are defined according to the required conditions for the industry. The turbine exit temperature as the air conditioning temperature is the most important parameter for the industry. The results show that exit temperature and total to static isentropic efficiency decreases with increasing inlet pressure while mass flow rate and output power increases. Also, the minimum outlet temperature of the turbine occurs at rotational speed of 62,400 rpm. Finally, the fan rotor isentropic efficiency, pressure ratio and power consumption increase with increasing mass flow rate and decreasing inlet temperature. Keywords : 3D numerical simulation, radial flow turbine, centrifugal fan, performance map.
