An IFR gas turbine with a rotor diameter of 23.76 cm is designed to operate with a gas mass flow of 1.0 kg/s at a rotational speed of 38,140 rev/min. At the design condition, the inlet stagnation pressure and temperature are to be 300 kPa and 727°C. The turbine is to be "cold" tested in a laboratory where an air supply is available only at the stagnation conditions of 200 kPa and 102°C.
a. Assuming dynamically similar conditions between those of the laboratory and the projected design determine, for the "cold" test, the equivalent mass flow rate and the speed of rotation. Assume the gas properties are the same as for air
b. Using property tables for air, determine the Reynolds numbers for both the hot and cold running conditions. The Reynolds number is defined in this context as
where ρ01 and μ1 are the stagnation density and viscosity of the air, Ω is the rotational speed (rev/s), and D is the rotor diameter.