The study of ultralow power turbine with diagonal impeller work process features

Аuthors

Kalabuhov D. S.

Samara National Research University named after Academician S.P. Korolev, 34, Moskovskoye shosse, Samara, 443086, Russia

e-mail: dskalabuhov@gmail.com

Abstract

The subject of the research is ultralow power turbine with axial nozzle set and diagonal impeller. The purpose of this work consists in improving the ultralow power turbine efficiency.

The paper describes the features of the work process in ultralow power turbines with diagonal impeller based on the equations of momentum and energy. It also studies the effect of the impeller degree of bias and the ways of its meridian profiling on energy characteristics of nozzle set, the impeller and the turbine in whole, using numerical methods for viscous flow 3D modeling with ANSYS CFX. The results of the analysis are based on theoretical concepts of work process within the diagonal turbine impeller.

The author derived equations of flow radial balance and flow energy within the impeller of diagonal type. It was found that implementation of diagonal impeller rather than axial provides an effective solution. It allows increase of power efficiency of the turbine. The turbine efficiency at rating conditions with loading implementation of diagonal impeller rather than axial parameter Y_T = 0,23, the rate of pressure reduction and calculated degree of reaction was increased by 9% due to diagonal impeller implementation with constant blade height in meridional section with impeller midline to turbine axis tilting angle . It was found also that impeller meridional profiling technique does not affect turbine effectiveness within the range of rational values .

Small size turbines with shaft power N_t = = 0.01...10 kW and working fluid flow are meant for various accessory drives and auxiliary power plants, energy systems for space and surface transport, as well as processing tools.

1. Implementation of diagonal impeller rather than axial allows power efficiency increase of about 9%. The highest efficiency increase is achieved with impeller midline to turbine axis tilting angle values . 

2. The method of the diagonal impeller meridian profiling does not affect the turbine efficiency within the range of , so it is recommended to use the most workable method of profiling with h_{i imp} = const. The results of the study display a significant effect of diagonality on impeller work process, which stipulates the necessity of further theoretical and experimental studies of the diagonal turbines and turbines with diagonal impellers of various types.

Keywords:

ultralow power turbine, diagonal impeller, degree of bias, power efficiency, degree of reaction

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