This study introduces a new approach to optimize the geometrical parameters of pipe diffusers in centrifugal compressors for Micro Gas Turbines, tailored for a 100 kW unit. The methodology draws insights from optimized airfoil-type diffusers and addresses the unique topological challenges of pipe diffusers, using diffuser maps to enhance design precision. The effectiveness of this method is validated through 3D-RANS based steady CFD simulations, using the ANSYS CFX solver. Comparative performance assessments at 100 percent rotation speed show that the best-performing pipe diffuser slightly trails its airfoil counterpart in efficiency, achieving 82.2 percent total-to-total isentropic efficiency compared to 84.4 percent. However, it offers a reduced frontal area, enhancing compactness. The analysis also reveals a dualistic impact from the leading-edge geometry of the pipe diffuser, which generates two counter-rotating vortices. These vortices have beneficial effects in pseudo and semi-vaneless spaces while introducing destabilizing factors in channel spaces. This investigation highlights potential trade-offs and outlines conditions under which adverse effects dominate, leading to significant flow separation. These insights pave the way for refining diffuser designs to better balance performance with spatial efficiency, marking a critical step forward in compressor technology of micro gas turbine for decentralized power systems.

翻译：本研究提出了一种优化微型燃气轮机离心压气机管道扩压器几何参数的新方法，针对100千瓦机组进行定制设计。该方法借鉴了优化翼型扩压器的设计思路，并解决了管道扩压器独特的拓扑结构挑战，利用扩压器图谱提升设计精度。通过基于三维雷诺平均纳维-斯托克斯方程的稳态计算流体动力学仿真，使用ANSYS CFX求解器验证了该方法的有效性。在100%转速下的对比性能评估表明，性能最佳的管道扩压器在效率上略逊于翼型扩压器，总对总等熵效率为82.2%，而翼型扩压器为84.4%。然而，管道扩压器具有更小的迎风面积，增强了紧凑性。分析还揭示了管道扩压器前缘几何形状的双重影响，产生了两个反向旋转的涡旋。这些涡旋在伪无叶区和半无叶区产生有益效果，而在通道区引入失稳因素。本研究突显了潜在的权衡关系，并概述了不利效应占主导、导致显著流动分离的条件。这些见解为优化扩压器设计以更好地平衡性能与空间效率铺平了道路，标志着微型燃气轮机离心压气机技术在分散式电力系统领域的关键进步。