Characteristics of the ship's active turbine stage that drives auxiliary mechanisms with counter-rotating impellers

Abstract

The paper discusses the current problems of increasing the efficiency of turbine drives for ship auxiliary mechanisms. Replacing a number of individual turbine drives for ship mechanisms with a pair of drives that are mechanically unconnected by counter-rotating impellers will increase the operational efficiency of the vessel. The research process has yielded the main geometric, regime, power and torque parameters depending on the speed characteristic for an active turbine stage with counter-rotating impellers.

It was found that for the investigated range of the speed characteristic, the change in the exit angle from the first working grid does not exceed 10 degrees, while for the second working grid, there was a sharp increase in the exit angle with an increase in the speed characteristic. The choice of the exit angles of the flow from the working grids was based on the high efficiency and power ratios of the impellers, which expanded the power range of the two auxiliary mechanisms driven by a single turbine stage. During the research, it was found that as the speed characteristic decreased, the difference between the powers of the impellers decreased. The analysis of the torque characteristics showed that the second impeller has a greater tendency to self-regulation, i.e., to maintain the rotational speed when the load on the rotor changes. The obtained power and torque performance indicators can serve as a basis for selecting auxiliary mechanisms driven by counter-rotating impellers when designing marine vessels and their power plants.