EXPERIENCE IN FLOW PARTS OF CENTRIFUGAL COMPRESSORS DESIGNING FOR TURBOEXPANDER UNITS

The author's comprehensive methodology for flow parts of centrifugal compressors designing, which are an important component of turboexpander units, is presented. The methodology includes mathematical methods and models of various levels of complexity - from one-dimensional to spatial, as well as experimental investigations. At the first step, a preliminary calculation of the geometric characteristics of the flow part is carried out using fairly simple methods based on solving one-dimensional or quasi-axisymmetric equations. The calculation of the main geometric characteristics of the flow part using the one-dimensional method is carried out on the basis of solving one-dimensional equations of mass conservation, rotalpy conservation (a consequence of the law of conservation of energy), and kinetic energy losses. The maximum power is chosen as the objective function. The search for geometric characteristics of the stage is carried out among a large number of options for varying parameters, taking into account the main design and operating restrictions. On the basis of the obtained geometric characteristics, a complete three-dimensional geometry is created, for which methods of analytical profiling of the blades of the flow parts are used, which allow creating turbine stages of axial, radial-axial and axial-radial types. The calculation of three-dimensional viscous flow is performed using the method of numerical integration of averaged Navier-Stokes equations and Menter's differential turbulence model. The description of the spatial shape of the compressor is carried out using the initial data method, for which there are a limited number of parameterized quantities are needed. An example of the developed compressor flow part is given, which has high gas-dynamic efficiency in a wide range of operating modes and in its characteristics corresponds to the best world analogues. It is shown that the calculated gas-dynamic characteristics of the compressors satisfactorily match the experimental data.