Development experience of the centripetal turbine flow part for an aviation engine air starter

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The subject of this paper is to study the approaches for the flow part design of a centrifugal turbine stage, which are considered on the example of an air starter with a capacity of 150 kW. The goal is to develop the spatial shape of the centripetal turbine flow part of the air starter of an aircraft engine. The tasks were as follows: determine the full 3D shape of the centripetal turbine of the air starter of an aircraft engine, sufficient for the development of design documentation, and calculate the gas-dynamic characteristics of the turbine, including the self-braking frequency. The research was carried out using modern numerical calculation methods and the design of radial-axial centrifugal turbomachine flow parts, implemented as a software complex IPMFlow. The following results were obtained. Two versions of the flow part have been developed: with profiled and thin rotor blades. The first version with profiled blades has better gas-dynamic characteristics, as well as reserves for further improvement, but it does not meet the requirements for strength. To eliminate the mentioned shortcomings of the first version, the method of blade profiling of radial-axial flow parts was improved, and with its help, a second version of the flow part with a rotor with thin blades, which has better characteristics in terms of strength and acceptable weight, was developed. This version was adopted as the basis for further design and production. Conclusions. The scientific novelty of the obtained results lies in the improvement of the method of radial-axial flow-part blade profiling. The proposed method provides such a shape of the blades that in a plane perpendicular to the rotor rotation axis, the blade centerline coincides with the radial line. In this case, the possibilities of so-called "spatial profiling" are reduced, in particular, the compound offset (saber-like) of the blades. This approach makes it possible to significantly reduce the load and stress under the action of centripetal forces. With the help of improved methods, a version of the flow part with a rotor and thin blades was developed. Although the efficiency of the turbine was slightly lower than that of the first version, it is quite high, and the power is more than the design value.