Impeller Splitter Blade Optimization for Gas Turbine Secondary Flow Control
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Solution Overview
Problem
In gas turbine engines, secondary flows create energy reduction and flow blockage issues due to three-dimensional vortical flow structures and non-uniform inlet pressure profiles, affecting energy transfer to the working fluid.
Innovation Solution
The design incorporates splitter blades with a chord length less than full blades, with specific flow channels and varying widths between them, which redirect secondary flows away from full blade suction sides, reducing mixing loss and flow blockage by adjusting the pitch and angle of splitter blades relative to the hub and tips.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If splitter blades are added to the impeller, then secondary flow and mixing loss are reduced, but device complexity increases
Solution Approach 1:
The impeller blade structure is segmented into two distinct types: full blades and splitter blades. The splitter blades are positioned between adjacent full blades and have a shorter chord length, creating a segmented blade arrangement that disrupts secondary flow patterns while maintaining overall structural integrity and reducing energy loss.
Solution Approach 2:
Splitter blades act as intermediary elements between full blades, serving as mediators that redirect and control secondary flows. These intermediate structures prevent direct interaction between opposing secondary flows from adjacent full blades, thereby reducing mixing losses without requiring complete redesign of the full blade structure.
2Productivity
If splitter blade chord length is reduced, then tip leakage flow is reduced and energy transfer efficiency is improved, but flow channel geometry becomes more complex
Solution Approach 1:
The splitter blades are designed with non-uniform local properties: their chord length is specifically reduced compared to full blades, and their pitch angles vary along the span from hub to tip. This local differentiation optimizes energy transfer efficiency by controlling tip leakage flow at critical locations while maintaining appropriate flow channel geometry elsewhere.
Solution Approach 2:
The design employs parameter changes by varying the chord length and pitch angle of splitter blades relative to full blades. The splitter blades have shorter chord lengths and adjusted pitch angles that change along the span, creating optimized flow control without requiring complex three-dimensional variable geometry throughout the entire blade structure.
3Loss of energy
If splitter blades are positioned closer to full blades, then secondary flow interaction is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The blade arrangement is segmented into alternating full blades and splitter blades with clearly defined spacing relationships. The splitter blades are positioned at specific intervals between full blades with defined pitch angles, creating a regular pattern that reduces secondary flow interaction while providing manufacturable geometric relationships that can be precisely controlled during fabrication.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enhances energy transfer efficiency by minimizing secondary flow interaction with tip leakage, reducing mixing loss and flow blockage, and preventing premature impeller stalling.
Implementation Method 1
a secondary flow that includes three-dimensional vortical flow structures develops in blade passages due to the rotation of the flow and to the non-uniform inlet pressure profiles
Implementation Method 2
a secondary flow that includes three-dimensional vortical flow structures develops in blade passages
Implementation Method 3
When the impeller rotates about its rotational axis, a secondary flow that includes three-dimensional vortical flow structures develops in blade passages due to the rotation of the flow
Data Source
AI summary
An impeller rotatable about a rotation axis, has a hub, blades extending from the hub to tips circumferentially distributed around the rotation axis, the blades having pressure sides and suction sides, the blades including splitter blades interspersed between full blades, a chord length of the splitter blades less than a chord length of the full blades, first flow channels defined between pressure sides of the splitter blades and suction sides of the full blades, second flow channels defined between suction sides of the splitter blades and pressure sides of the full blades, respective widths of the first and second flow channels at a given rotor location defined between adjacent splitter and full blades at the given rotor location, a width of the first flow channels increasing from the hub to the tips of the splitter blades along at least a portion of the chord length of the splitter blades.