Mixed Flow Turbine Hub Geometry to Suppress Flow Separation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing turbines suffer from flow separation on the surface of the turbine wheel, which reduces efficiency, and existing technologies do not effectively address this issue.
Innovation Solution
A mixed flow turbine design with specific blade configurations, including blades positioned on the outer side in the radial direction and a hub with a distance relationship Dh/Eave>0.4, along with a casing structure that includes a shroud wall, scroll outer peripheral wall, and dividing wall to manage flow paths, reducing adverse pressure gradients and promoting smooth flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional turbine blade configuration is used, then manufacturing is simpler, but flow separation occurs on the turbine wheel surface reducing efficiency
Solution Approach 1:
The patent applies local quality by creating a hub with non-uniform geometry where the outer peripheral surface has a specific distance relationship (Dh/Eave>0.4) from the rotational axis. This local geometric modification at the hub region optimizes flow characteristics without changing the entire turbine structure, suppressing flow separation while maintaining manufacturing feasibility.
Solution Approach 2:
The patent introduces a new geometric dimension by positioning blade leading edges such that tip ends are radially outward from hub ends, creating a three-dimensional blade configuration. This spatial arrangement in the radial direction optimizes flow attachment on the turbine wheel surface, improving efficiency without excessive complexity.
2Productivity
If blade leading edges are positioned with tip ends radially outward from hub ends, then flow separation is suppressed, but manufacturing precision requirements increase
Solution Approach 1:
The patent uses parameter changes by defining a specific geometric ratio Dh/Eave>0.4 as the design criterion. This quantitative parameter provides a clear manufacturing target, allowing precision control through measurable geometric relationships rather than complex positional specifications, thus balancing efficiency improvement with manufacturability.
3Productivity
If hub outer peripheral surface is positioned at specific distance from rotational axis, then adverse pressure gradient is reduced, but device complexity increases
Solution Approach 1:
The patent applies local quality by modifying only the hub region geometry to achieve Dh/Eave>0.4, while keeping the rest of the turbine structure conventional. This localized geometric optimization reduces adverse pressure gradients and suppresses flow separation without requiring complex changes throughout the entire device.
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
The design suppresses flow separation and enhances turbine efficiency by minimizing adverse pressure gradients and promoting smooth flow, resulting in improved turbine performance.
Implementation Method 1
a turbine wheel (8) including a hub (12), and blades (14) provided on an outer peripheral surface (18) of the hub (12) at intervals in a circumferential direction of the hub (12)
Implementation Method 2
Since a separation of a flow on a surface of the turbine wheel is a factor that reduces turbine efficiency, it is important to suppress the separation on the surface of the turbine wheel
Data Source
AI summary
This mixed flow turbine is provided with a turbine wheel comprising a hub and blades provided at intervals in a circumferential direction of the hub on an outer peripheral surface of the hub. The tip ends of the leading edges of the blades are positioned on an outer side in the radial direction of the turbine wheel than the hub ends of the leading edges. When a distance between the downstream end of the outer peripheral surface of the hub and a rotational axis line of the turbine wheel is Dh and the average of distances between respective positions from the hub ends to the tip ends at the leading edges and the rotational axis line is Eave, Dh/Eave>0.4 is satisfied.