Multimode optimization of a birotational gas turbine of a turboshaft engine
The article discusses the problem of the expediency of using birotate schemes in constructions of gas turbines of aircraft turboshaft engines. As a means of solving this problem, the OPTBGT software complex created by the author was used. This program was implemented using the method of structural programming and was designed for multi-mode computer optimization of flow parts of gas turbines with sliding of conventional rotor and birotate rotor. For a two-stage (with high-pressure and low-pressure turbines) gas turbine of the specific turboshaft engine, three variants of turbines were considered: conventional type, birotating turbine with nozzle apparatuses in the low-pressure turbine, birotating turbine without nozzle apparatuses in the low-pressure turbine. Multi-mode computer optimization was carried out in four modes: takeoff, maximum continuous, cruising and low-gas modes. The variant of the turbine without nozzle apparatuses in the low-pressure turbine in the takeoff mode has a reduction of about 16 % of the efficiency of the low-pressure turbine as compared to the variant of conventional turbine because of high losses of kinetic energy with output velocity. The variant of the turbine with nozzle apparatuses in the low-pressure turbine in all modes has an increase of about 1 % of the efficiency of the low-pressure turbine as compared to the variant of conventional turbine because of the reduction of profile and secondary losses in nozzle apparatuses of the low-pressure turbine because of the reduction in nozzle apparatuses of 77 degrees of the angle of the rotation of the flow.