Обоснование выбора расчетной области в задачах моделирования вязкого потока в малорасходных ступенях центробежного компрессора

В работе рассматривается вопрос определения расчетной области проточной части (ПЧ) при численном моделировании (RANS-подход) вязкого потока газа в малорасходной ступени центробежного компрессора с условным коэффициентом расхода Ф=0,008. Рассматривается несколько вариаций замены конструкционной сборки проточной части модельной ступени газодинамической моделью: основной рабочий тракт ступени; основной рабочий тракт ступени с учетом входного участка – патрубок и обтекатель;  основной рабочий тракт ступени с учетом притрактовых областей с полным и частичным присоединением к проточной части; основной рабочий тракт ступени с учетом поверхностей трения ступицы рабочего колеса.

The investigation of absolute flow non-uniform velocity distributions influence at the centrifugal compressor axial radial impeller inlet using numerical calculation methods in ANSYS CFX.

Abstract. Currently, methods of numerical modelling are widely used. They are especially widely used in the design of turbo compressors. For the specific task of designing new flowing parts of a centrifugal compressor, it is not recommended to deviating from the canonical design techniques, but it is preferable to supplement them with numerical methods. This article is devoted to the end two-element stage investigation of a centrifugal compressor with an axial radial impeller, the stage main dimensions were obtained by the method of V.F.  Rice. In order to obtain the necessary pressure characteristics and determine the dependence for the absolute velocity non-uniform distribution at the inlet to the axial radial impeller, the flow path main dimensions were optimized using numerical calculation methods.  The calculation was performed using the SST turbulence model using computational gas dynamics methods in the ANSYS CFX software environment.  Based on the optimization results, five compressor designs and corresponding characteristics were obtained.  The absolute velocity distribution nature at the inlet to the centrifugal compressor axial radial impeller for five flow path variants is investigated.  Empirical dependences are obtained for the deviation at the inlet to the absolute velocity in the hub section axial radial impeller and the absolute velocity deviation at the shroud from the absolute velocity at the average diameter based on the results of a numerical experiment.  Recommendations are made for further absolute velocity distributions investigating at the inlet to the compressor impeller.

Contamination effects study in the centrifugal compressor flow stage by means numerical simulation methods.

Abstract. At the moment there is no effective way to clean the flow of the turbine unit, which is justified from an economic point of view. It is important to understand how deposits affect compressor performance and the need to clean contaminants. In the available literature, such studies are not described. The computational the model stage domain for the study includes the following elements: inlet pipe, impeller, bladeless diffuser, swivel elbow, backward guide apparatus, outlet pipe. For calculations, the computational fluid dynamics methods in the Ansys software package were used. A numerical experiment was carried out in six mass flow rate variants, two impeller revolutions  variants, and three different sediment thicknesses in the flow part variants. Based on the numerical experiment the results, the calculated machine operating modes characteristics are constructed. The analysis revealed that the studied deposits cause a drop in the stage characteristics by 1.5-2%. Losses in the stage increase in proportion the thickness deposits in the compressor flow part.

Improving the reliability of the compressor unit using the wavelet transform method.

Abstract. Centrifugal compressors are an integral part of modern production in such industries as gas transmission, oil refining, metallurgical, machine-building, mining, as well as in electric and heat power engineering. Interruptions in the operation or failure of the compressor lead to decrease in profit or large material loss. Conditions should be created for the safe (stable) operation of the centrifugal compressor. Surge is global (complete) loss of stability, an unacceptable phenomenon for a centrifugal compressor. Compressor surge protection must function during operation. The algorithms used to protect the centrifugal compressor against surge have some drawbacks, which make it impossible to reliably exclude surge.There are many methods for analyzing rapidly changing processes in the flow part of a centrifugal compressor. The wavelet theory is the most accurate and modern method. The use of the wavelet transform method for signal processing allows us to solve the problems of analyzing non-stationary processes of a centrifugal compressor to expand the acceptable range of work and build reliable operation of the anti-surge diagnostic system. In the future, it is possible to use other basic wavelet functions, for comparison and selection of the most suitable one, for the analysis of unsteady signals in a centrifugal compressor.


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