Structure and Design Method of Interstage Transition Section of Partially Intake Turbine with Low Intake Gas

Abstract

The invention relates to a low-admission degree partial admission turbine interstage transition section structure and a designing method thereof.The radius of the inner end wall of a transition section and the radius of the outer end wall of the transition section keep invariable in the axial direction, and speed reducing and pressure diffusing are only performed in the circumferential direction of the transition section; the pressure diffusing capacity of the circumferential side wall face, along the air flow prewhirling direction, of the transition section is higher than that of the other circumferential side wall face of the transition section.For overcoming the adverse pressure gradient which is caused by partial admission and generated at the side wall face, along the air flow prewhirling direction, of an inlet of the transition section, the circumferential side wall face is firstly contracted and then expanded, the adverse pressure gradient caused by partial admission is overcome in an air flow accelerating mode, and flowing loss of the transition section is reduced.In addition, the expansion angle of the circumferential wall face, along the air flow prewhirling direction, of the transition section is determined according to the velocity vector sum of main flow in an admission area and clearance flow in a non-admission area, and then the optimal expansion angle can be obtained.The low-admission degree partial admission turbine interstage transition section structure can be directly applied to low-admission degree multistage partial admission turbine interstage, speed reducing and pressure diffusing are performed in the circumferential direction of the transition section to increase the air volume flow after air flow enters the transition section, therefore, the admission degree of a back-stage turbine of the transition section is improved, and then the aerodynamic performance of the back-stage turbine is improved.

Description

Technical field [0001] The invention relates to a structure of a transition section between stages of a low intake degree partial intake turbine and a design method thereof. The transition section is suitable for a low intake degree multi-stage partial intake axial flow turbine. Adopting the structure of the inter-stage transition section can increase the air intake of the turbine at the latter stage of the transition section, thereby improving the aerodynamic performance of the turbine at the latter stage of the transition section. Background technique [0002] The aerodynamic performance of part of the intake axial turbine decreases with the decrease of the intake degree. Therefore, in the design, it is hoped to maintain a large intake area under permitted conditions so that the turbine performance will not decrease too much. However, in some application areas, the characteristics of high total pressure at the turbine inlet and small volume flow make the turbine air intake smal...

AI Technical Summary

Problems solved by technology

However, due to the flow characteristics of the partial intake turbine itself, the aerodynamic design of the transition section between the turbine stages is significantly different from that of the gas turbine diffuser. The intake area is connected to the front and rear stages of some intake turbines, so the interstage transition section of some intake turbines is not a complete circle in geometry; the clearance flow in the non-intake area caused by the partial intake effect causes the inlet flow of the transition section The uniformity is poor, and the flow loss in the transition section is large; the inlet airflow pre-swirl in the transition section is large, and the deceleration and diffusion process of the working medium in the transition section mainly occurs in the circumferential direction of the transition section, so the expansion of the circumferential side wall of the transition section The angles are not consistent; the uniformity of the air flow at the exit of the transition section has a significant impact on the aerodynamic performance of the subsequent stage turbine, so the inter-stage transition section must not only increase the volume flow rate of the working medium, but also ensure the uniformity of the exit air flow of the transition section; The mechanism of influence on the aerodynamic performance of the transition section is also unknown

Images