Investigation of Discharge Coefficients for Single Element Lean Direct Injection Modules

Han Yu,Longxi Zheng,Pengfei Zhu,Jianqin Suo

doi:10.3390/en11061603

Abstract

Lean direct injection (LDI) combustion has a high potential as a low pollution combustion method for gas turbines. The present research aims to further investigate the discharge coefficient of an LDI module, axial swirler and convergent outlet under non-reaction and reaction conditions by theoretical, numerical and experimental methods. The functional relationship between the discharge coefficient of the LDI module, axial swirler and convergent outlet was established, and the effect of swirl angle (30°, 32°, 34°, 36°, 38°, 40°) and vane number (11, 12, 13, 14, 15, 16) on discharge coefficient was studied, and finally the differences in effective flow area of LDI combustor under different inlet conditions were analyzed. The results indicate that the flow separation on the suction side increases as the swirl angle increases, which leads to a decrease of the discharge coefficient of the axial swirler, however the discharge coefficient of the convergent outlet remains unchanged first and then decreases. As the vane number increases, the flow separation on the suction side decreases and the flow friction loss increases, so that the discharge coefficient of the axial swirler and convergent outlet will first increase with the increase of vane number and then decrease with further increases. The effective flow area of combustor changes as the conditions change, but it is approximately equal under high power conditions and normal temperature and pressure conditions.

Highlights

With the increasingly stringent emission regulations on civil aircraft engines [1], modern low emission civil aircraft engines are being developed, and several low emission strategies have been successively proposed, such as Rich-burn Quick-quenching Lean-burn (RQL) [2], Lean PremixedPrevaporized (LPP) [3], and Lean Direct Injection (LDI) [4]
For different combustor inlet parameters, the optimized dome scheme could be obtained by varying the arrangement of LDI modules; this concept is referred to as Multi-Point Lean Direct Injection (MPLDI) [6]
Theofeffect of swirl angle on the discharge coefficient of the axial swirler is shown in Figure 5, 4.1.1

Summary

Introduction

With the increasingly stringent emission regulations on civil aircraft engines [1], modern low emission civil aircraft engines are being developed, and several low emission strategies have been successively proposed, such as Rich-burn Quick-quenching Lean-burn (RQL) [2], Lean PremixedPrevaporized (LPP) [3], and Lean Direct Injection (LDI) [4]. LPP technology will have low levels of emissions if the design and development are reasonable, but due to premixed and prevaporized combustion, the combustor is prone to auto ignition, flashback and combustion instability, and especially the severe combustion instability restricts the development of LPP technology. In the LDI concept, fuel and air are directly injected into the combustor, so that the auto-ignition and flashback would be avoided due to the non-premixed combustion, and the combustion instability is not as serious as in LPP, the LDI approach is not inferior to LPP in its ability to reduce emissions [5]. For different combustor inlet parameters, the optimized dome scheme could be obtained by varying the arrangement of LDI modules; this concept is referred to as Multi-Point Lean Direct Injection (MPLDI) [6]. For LDI combustors, the roles of the LDI module are quick mixing of fuel and air, ensuring the correct quantity of combustion air, forming the suitable

Methods

Results

Conclusion