Turbine Blade Hub Endwall Flow Path Width Configuration
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Solution Overview
Problem
Increasing the profile thickness near the middle of a turbine blade's hub endwall to enhance strength leads to a transition in flow path width from shrinkage to expansion, resulting in deteriorated flow velocity distribution and efficiency decline.
Innovation Solution
A turbine design where the flow path width at the hub endwall decreases to a minimum near the leading edge and increases towards the trailing edge, with a reference blade height between 5% and 25% of the blade height, ensuring strength and effective flow induction to the hub endwall, thereby stabilizing flow velocity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the profile thickness near the middle of the hub endwall of the blade main body is increased to improve strength, then the strength of the rotating turbine blade is improved, but the flow path width undergoes a transition from shrinkage to expansion near the middle in the flow direction, leading to deterioration in flow velocity distribution and rapid deceleration on the blade back face
Solution Approach 1:
The invention applies different geometric characteristics to different regions of the blade. Specifically, the flow path width at the hub endwall is designed to have a minimum point between the leading edge and trailing edge, creating a localized geometric feature that controls flow behavior in that specific region without affecting the overall blade strength. This local geometric modification allows the flow to be properly directed while maintaining the necessary structural integrity.
Solution Approach 2:
The invention addresses the two-dimensional flow distribution problem by introducing a three-dimensional geometric configuration. The flow path width is designed to vary in the axial direction (hub endwall to tip), with the minimum width position shifting from the hub endwall toward the trailing edge. This dimensional approach allows control of flow velocity distribution through spatial geometry rather than merely adjusting profile thickness.
2Strength
If the profile thickness near the middle of the hub endwall is increased, then the strength is improved, but the flow path width transition causes rapid deceleration on the blade back face, resulting in efficiency decline
Solution Approach 1:
The invention modifies the local geometric quality of the flow path at the hub endwall by positioning the minimum flow path width between the leading edge and trailing edge. This localized geometric feature ensures that the flow maintains appropriate velocity distribution in the critical hub region, preventing energy loss due to rapid deceleration while allowing profile thickness to be optimized for strength elsewhere.
3Productivity
If the flow path width at the hub endwall is designed to decrease to minimum and then increase toward the trailing edge, then flow velocity distribution is improved, but the position of minimum flow path width must be precisely controlled to avoid flow rate insufficiency on the trailing edge side
Solution Approach 1:
The invention establishes the minimum flow path width position as a predetermined design parameter located between the leading edge and trailing edge at the hub endwall. By pre-defining this critical geometric feature in the design stage, the flow velocity distribution can be optimized without requiring complex adjustments during manufacturing. The position is set to coincide with or be upstream of the trailing edge, providing a clear design guideline that simplifies manufacturing precision requirements.
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 suppresses the rapid decline in flow velocity on the blade back face, maintaining high efficiency and strength while preventing flow rate insufficiency on the trailing edge side.
Implementation Method 1
on the trailing edge side, three-dimensional flow rate redistribution is performed for a flow to be induced from the reference blade height side to the hub endwall side
Data Source
AI summary
A flow path width at a hub endwall of a blade main body decreases toward a minimum width from a leading edge, and increases toward a trailing edge from the minimum width, the flow path width at a reference blade height aparted toward a tip side from the hub endwall of the blade main body gradually decreases toward the trailing edge from the leading edge, and an axial chord length position of the minimum flow path widths at respective blade height shift toward a transition to the trailing edge side from the hub endwall toward the tip side of the blade main body and coincides with the trailing edge at the reference blade height.