Progress in research on flow and wear characteristics of compressed air energy storage centripetal turbine

The compressed air energy storage system is a key technology to promote the large-scale application of renewable energy. China's wind energy, solar energy and other renewable energy are mainly distributed in the western region. This makes the compressed air energy storage device work in the western sand environment all year round. The centripetal turbine is a key work component of the compressed air energy storage system. It has the characteristics of "high flow velocity of the working medium and high speed of the impeller". The internal dust may cause wear on the wall surface and affect the service life of the centripetal turbine. Recently, the Energy Storage R & D Center of the Institute of Engineering Thermophysics of the Chinese Academy of Sciences has carried out research on the flow and wear characteristics of the centripetal turbine of the compressed air energy storage system, and made new progress.

On the basis of considering the internal flow of the centripetal turbine, the researchers further introduced the effect of dust on the solid wall wear, and finally established a three-dimensional numerical model of the "gas-solid" multiphase flow of the centripetal turbine. By coupling to solve the full three-dimensional Navier-Stokes hydrodynamic governing equations and Tabakoff & Grant semi-empirical formula of wear, on the basis of completing the model verification, further study of the centrifugal turbine vanes, centrifugal turbine vanes, different impeller tip clearance sizes and expansion ratios The distribution characteristics of the amount of wear on the rotor blades, the hub and the wall of the wheel cover, the trajectory of the dust inside the centripetal turbine, and the corresponding airflow distribution structure inside the centripetal turbine (see Figure 1). Finally, the change rule of the maximum wear distribution area of ​​the centripetal turbine wall with the tip clearance and the operating expansion ratio was obtained, and the variation range of the best impeller tip clearance and the optimal operating expansion ratio under the conditions of comprehensive aerodynamic efficiency and wear amount were further determined.

The research results show that the trailing edge of the stationary blade, the leading edge of the moving blade, and the surface of the hub and wheel cover between them have the largest wear. As the blade tip clearance increases, the blade wall wear has the characteristic of "decrease first, then increase". When the blade tip clearance is near 2% of the outlet blade height, the amount of wear is the lowest (see Figure 2), and a comprehensive consideration is determined Under the influence of aerodynamic efficiency and wear, the optimal blade tip clearance value range of the centripetal turbine; when the centripetal turbine expansion ratio gradually increases to 2.02, the wall of the turbine outlet area begins to be affected by dust, but the wear range of the impeller leading edge is significantly reduced. The centripetal turbine isentropic efficiency is only about 0.1% lower than the highest value. Based on the above research results, it can provide guidance for the engineering application of the anti-wear technology of the centripetal turbine, and at the same time provide a reference for the determination of the design parameters of the centripetal turbine for compressed air energy storage.

Related research is supported by the National Natural Science Foundation of China (51806211) and the Beijing Natural Science Foundation of China (3184063). The research results have been included in the international journal Energy.

Fig. 1 (a) "Air-dust" multi-phase flow solution domain (b) distribution of wear on the wall of the centripetal turbine (c) trajectory of dust movement in the centripetal turbine (d) distribution of airflow lines in the centripetal turbine

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