Pre-swirler Dimples for Gas Turbine Cooling Airflow
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Solution Overview
Problem
Gas turbine blades face cooling challenges due to hot combusted gases, requiring effective cooling air control to prevent performance degradation while minimizing parasitic and pressure losses.
Innovation Solution
A pre-swirler unit with blades featuring concave and convex surfaces and dimples is introduced to swirl cooling air, reducing drag force and enhancing airflow, comprising a shroud with specific side surfaces and grooves for assembly and airflow management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If cooling air is swirled by the pre-swirler to match blade rotational speed, then parasitic pumping losses are reduced, but pressure losses increase
Solution Approach 1:
Dimples are introduced at specific locations on the pre-swirler blade surfaces to locally modify flow characteristics. The dimples create localized turbulence and vortices that enhance momentum transfer and reduce drag in critical regions, allowing the pre-swirler to achieve better swirl performance with reduced overall pressure loss.
Solution Approach 2:
The dimples introduce curved surface features that modify the flow path and create beneficial vortical structures. These curved surfaces on the dimple walls generate localized secondary flows that enhance mixing and reduce parasitic losses while maintaining the required swirl angle for effective turbine blade cooling.
2Ease of manufacture
If conventional smooth pre-swirler blades are used, then manufacturing is simpler, but drag force is higher and airflow is poorer
Solution Approach 1:
The dimpled surface creates a controlled porosity effect on the pre-swirler blade surface. This porous-like structure allows for better boundary layer control and reduced skin friction drag, while still maintaining structural integrity and manufacturability through standard forming processes.
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 pre-swirler unit effectively reduces drag force and improves airflow, minimizing parasitic and pressure losses while maintaining turbine performance by efficiently controlling cooling air swirl.
Implementation Method 1
the convex side surface comprises a first plurality of dimples... the concave side surface comprises a second plurality of dimples... improving the flow of the cooling air on the surface
Implementation Method 2
lowering drag force and improving the flow of the cooling air on the surface
Implementation Method 3
The pre-swirler swirls the cooling air circumferentially up to the rotational speed of the corresponding blade of the turbine
Data Source
AI summary
A pre-swirler unit can include: a shroud including a bottom surface and a top surface opposite to the bottom surface; a blade disposed on the top surface and including a leading edge and a trailing edge, wherein the blade comprises a concave side surface and a convex side surface that are disposed between the leading edge and the trailing edge, wherein the convex side surface comprises a first plurality of dimples, and wherein the concave side surface comprises a second plurality of dimples.