# Angle-Regulating Rule of Guide Vanes of Variable Geometry Turbine Adjusting Mechanism
## 1 Introduction  
Figure 1 shows the conventional engine turbine structure. The guide vanes of the conventional engine turbine are fixed. They cannot rotate. Figure 2 shows the variable geometry engine turbine structure. The guide vanes of the variable geometry engine turbine are not fixed. They can rotate. The variable geometry turbine is a crucial component of the variable cycle engine. The research on variable geometry turbines has received attention at home and abroad. The adjustable guide vane angle is the leading way to realize the variable geometry turbine. It is also the main research direction of the variable geometry turbine. The design idea is to install a set of mechanical adjustment mechanisms outside the engine casing. The guide vanes are driven to rotate by the adjusting mechanism. Through the rotation of the guide vanes, the working angles of the guide vanes are changed. This changes the exhaust area of the turbine guide structure. It realizes the adjustment of the work distribution between the high-pressure rotor and the low-pressure rotor. Its main feature is to change the flow matching between the moving blade and the guide vane in the turbine. The airflowarea in the turbine passage is changed. The overall working performance of the turbine is improved [1,2]. The candidate engine F120 of the American F22 fighter is a variable-cycle engine. The turbine guide vane adjustment of \(\mathcal{T}^{\circ}\) can bring about a 10% flow change in the machine [3]. In recent years, variable cycle engines have been a new development direction for turbines. However, achieving variable geometry functionality required work. It was necessary to consider various factors, such as operating environment, structural space, and functional implementation. The compressor could realize variable geometry functions. Rotating guide vanes and variable geometry structures were the main research directions. [PERSON] [4] studied the application of mathematical models to analyze the dynamic process in gas turbines. The influence of variable geometry compressors on airflow characteristics was introduced in detail, making it possible to numerically simulate the aerodynamics of variable geometry compressors [5] with rotating guide vanes in the future. [PERSON] et al. [6] conducted a numerical study of airflow characteristics in a centrifugal compressor. A comparison was conducted between the nonguide vane scheme and the scheme with guide vanes. At different conditions, the efficiency of the intake chamber  
Figure 1: Turbine structure of conventional engine. Figure 2: Turbine structure of variable geometry engine. of the compressor had increased by 4.97% on average. [PERSON] et al. [7] studied numerical simulation and optimization analysis on the working mechanism of variable guide vanes in transonic compressors. The joint angle of a seven-stage transonic compressor was optimized. A new phenomenon had been discovered where the angle adjustment affected its performance and that of adjacent downstream blades and the performance of upstream blades. At different angle openings, joint adjustment optimization improved efficiency by 0.2-1.93%. [PERSON] et al. [8] introduced the experimental research results of turbochargers with different designs. The turbocharger was designed as a single-inlet and dual-inlet turbocharger with a variable geometry structure. A significant depreciation in efficiency was measured between the single- and twin-entry configurations due to the mixing effects. The nozzles unit provided the best compromise in performance at different speeds. Variable geometry compressors were easier to achieve variable cycle performance compared to turbines. Because compressors did not need to consider the effects of high-temperature thermal deformations and flexible bodies, this was significantly different from variable geometry turbines. The gas turbine blades were scoured by high-temperature gas sustainedly and long term in harsh environments.