Collaboration between the Samara National Research University  and the JSC “KUZNETSOV”  included the research efforts in the field of increasing the performance of NK-36ST  gas turbine power plant intended for use as a driving unit of a gas compression station. The requirements included 3% increase in engine efficiency while keeping the maximum number of engine parts unchanged.
First, the thermogasdynamic simulator of the NK-36ST gas turbine power plant was developed and verified using the results of experimental investigations. The impact of various parameters of the engine upon its efficiency was thoroughly investigated and the approach to modernization preserving most of the engine parts was suggested. This approach included increasing the values of work process parameters, the hydraulic efficiency of turbomachinery and reducing the cooling air consumption.
Second, the analysis of the working process of turbomachinery was carried out. The air-gas channel in a meridional section was kept unchanged for the first iteration, thus keeping the parts of the initial engine unchanged, except for the blades and vanes of turbomachinery. For this variant, the parameters of compressors (head ratio and flow ratio) changed to more favorable values, supposedly providing 1–2% higher efficiency. Unfortunately, for this variant and the given restrictions the points, corresponding to the parameters of turbines moved at the Smith diagram to the unfavorable areas, thus making the increase in turbine efficiency very unlikely. The analysis had shown that to provide more convenient values of turbine parameters the blades should be shortened, and this decrease in blade length provides the possibility to increase the rotational speed of the rotor with the same strain levels of the blades and disks. As the result, the gas channel configuration and values of rotational speeds for the turbines providing the increase in their efficiency by 0.5%–1.0% were suggested. The suggested gas channel configuration preserves the same inner diameters thus keeping the disks layout the same.
At the next stage, the shapes of the low-pressure turbine and compressor blades and the blades of free turbine were optimized using the Profiler program (developed at the Samara University), the NUMECA  system and the IOSO  optimization package, providing the 0.5%–1.0% increase in the efficiency in comparison to the initial variant.
The results of the described research efforts provide the increase in engine efficiency of about 3% while providing the possibility to keep most of the rotor parts of the engine unchanged.