Axial-Swept Influence on Inner Flow Performance of HP Steam Turbine Based on CFD

Zi-Ming Feng,Jindong Zhang,Chenhao Guo,Huibin Gu,Bingkun Wei,Wei Cui

doi:10.1155/2019/5363496

Zi-Ming Feng, Jindong Zhang + Show 4 more

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https://doi.org/10.1155/2019/5363496

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Abstract

Swept blade technology was used to redesign the supercritical steam turbine sets that could improve the inner-efficiency of turbine sets and decrease the consumption of coal the noxious gas such as NOx. The eighth high-pressure stages, including static and rotor cascades, were selected as tested prototypes that were blew in the low-velocity wind tunnel. We used the five-hole ball head needle to measure the aerodynamic parameters distribution along the width and span direction of the high-pressure stage cascades. With the inkblot display technology, the limit flow spectrums were displaced in the blade surface and the endwalls. These tested data could be used to check the simulation results of CFD software. To improve the efficiency of the steam turbine high-pressure (HP) stage, we selected the supercritical steam turbine HP stage cascade blade as the prototype to research into its inner flow performance of the axial-swept blade by the CFD software. Two different redesigned blades, with ±20°, swept angle, and 30% swept height, named axial fore-swept and axial aft-swept, were built up. The stage passages flow field of the prototype blade, and the two redesigned swept blades were simulated using CFD software with stage interface planes between the stages. The CFD simulation results indicated that the leading edge of swept blades influenced the inlet flow field; the pressure in aft-swept blade stage in both endwalls was higher than in the middle and was beneficial to improve the passage flow properties of HP stage. But for the fore-swept HP stage, its pressure distribution was lower in both endwalls than in the middle and not beneficial to passage flow.

Highlights

In recent years, as oil and coal were becoming scarce and their prices were rising, people paid more attention to the problems of energy conservation and environmental protection than before; at the same time, many countries planned to develop steam turbine power station with high efficiency
The results indicate that blade sweep does affect inlet radial equilibrium, such as blade camber angles, solidity
The results show that the nonuniformity induced by the inviscid blade force will reorganize the inlet flow field of the blade passage and change the inlet flow angle, causing the redistribution of the radial balance of the inlet [28]

Summary

Introduction

As oil and coal were becoming scarce and their prices were rising, people paid more attention to the problems of energy conservation and environmental protection than before; at the same time, many countries planned to develop steam turbine power station with high efficiency. Improving turbine machinery internal efficiency is one of the eternal targets for turbine mechanical engineers and scientific researchers. People had attempted many methods to improve the internal efficiency of the steam turbine and have achieved a lot of achievements. It is found to be a good idea following the design concept of an aircraft wing. The swept concept of turbine cascade came from the swept aircraft wing. From 1950 to 1970, Beatty [1], Godwin [2], Smith [3], Lewis [4], and so on researched low-speed tests of aft-swept blades with a straight leading edge. Gostelow & Smith’s [5]

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Conclusion