1. United Technologies Research Center
Turbomachinery in Propulsion Engines -- Problems Rensselaer – Hartford Campus
Dr. William T. Cousins
United Technologies Research Center
Text: S. Larry Dixon and C. Hall, “Fluid Mechanics and Thermodynamics”, 7th ed, Elsevier Inc., ISBN-10: ISBN-13:

2. Information for Problems 10, 11, 12 and 13
If needed, use:
For the Turbine: Cp = kJ/kg K, R = kJ/kg K, γ = 1.33
For the Compressor: Cp = kJ/kg K, R = kJ/kg K, γ = 1.4
Engine Inlet conditions are standard day inlet conditions.
The single stage turbine in the J-30 was designed to drive the 10-stage axial compressor. The design point specifications for the compressor are mdot = 30 lbm/sec and P02/P01 = 3.8, at an operating speed of 17,000 rpm, with an efficiency of The average mean radius of the compressor is m.
The measured hub radius, tip radius, the mean radius values of angles α2 , β2 and β3 of the turbine, the mean radius spacing sm , and the axial chord bZ of the blades, was measured as shown in the two following figures, and the values obtained.
rh = m rt = m α2 = 60° β2 = 30° β3 = -57° sm = 0.02 m bZ = m

3. Problem 10
Estimate (be sure to list any assumptions you might make) the density of the combustion products in the turbine. Assume a 5% loss of total pressure in the burner, and a combustion temperature of 1100 K.

4. Problem 11 (page 1)
Using the data provided, calculate CX/Um for the turbine. Assume that mdot fuel = 3% of the mass flow rate of the air. Also, while you have the measured turbine hub and tip radius, assume there is a 5% area blockage (reduction) due to the fact that there are turbine blades in the flow path.

5. Problem 12
Using the turbine design spreadsheet presented in class, find Δh0/Um2 and α3 . Find the turbine efficiency ηtt from the Smith chart. Sketch the velocity triangles.

6. Problem 13
Using Z = 0.8, predict the blade spacing s, and compare the prediction with the measurements.