Corrugated Turbomachine Blade Trailing Edge Wake Mixing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Turbomachine blades experience significant aerodynamic losses due to unsteady mixing of wakes with downstream blade rows, caused by the finite thickness of airfoil trailing edges, leading to velocity deficits and increased mixing losses.
Innovation Solution
The introduction of corrugated surfaces on the outer surfaces of turbomachine blades, extending from the trailing edge to the leading edge, which enhance the mixing process by creating discrete vortices and reducing the magnitude of wake flow impinging on downstream blades, thereby minimizing inflated unsteady mixing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the trailing edge thickness of the airfoil is increased to maintain structural strength, then the blade can withstand higher mechanical loads, but the wake mixing losses increase due to larger velocity deficits
Solution Approach 1:
The trailing edge is segmented into multiple thin elements arranged in a specific pattern, creating a controlled wake structure that reduces mixing losses while maintaining structural integrity through the distributed arrangement of segments
Solution Approach 2:
The trailing edge design transitions from a two-dimensional flat surface to a three-dimensional structured configuration with specific spacing and orientation of segments, creating beneficial wake patterns that reduce downstream mixing losses
2Loss of energy
If the axial distance between blade rows is increased to allow wake recovery, then mixing losses are reduced, but the turbomachine length and power density decrease
Solution Approach 1:
The trailing edge structure pre-conditiones the wake before it reaches downstream blade rows, creating a wake pattern that mixes more efficiently over shorter distances, thereby allowing reduced axial spacing between blade rows while maintaining low mixing losses
Solution Approach 2:
The trailing edge geometry parameters (segment spacing, angle, thickness distribution) are optimized to control wake evolution rate, enabling faster wake recovery and mixing that allows reduced axial distances between blade rows
3Loss of energy
If complex air jet systems are used to enhance wake mixing, then mixing efficiency improves, but device complexity and manufacturing cost increase
Solution Approach 1:
The trailing edge structure itself generates the desired wake mixing effect through its geometric configuration, eliminating the need for external air jet systems or active control mechanisms while achieving improved mixing efficiency
Solution Approach 2:
The complex air jet mixing enhancement systems are extracted and replaced by a passive geometric trailing edge design that achieves mixing enhancement through its structure alone, simplifying the overall system
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 design reduces aerodynamic losses and enhances thermal efficiency by accelerating the mixing process, allowing for a reduction in the axial distance between blade rows and increasing power density without the need for complex air jets or reduced trailing edge strength.
Implementation Method 1
The wave mixing structures can take a variety of forms such as crenulated or serrated trailing edges on the airfoils
Implementation Method 2
The relative flow velocity exiting, for example, a gas turbine airfoil is quite high, typically with Mach numbers of 0.5 or higher. The finite thickness of an airfoil trailing edge, however, creates a velocity deficit, i.e., a wake, which introduces losses in the flow through viscous mixing
Data Source
AI summary
A blade includes an airfoil body defined by a concave pressure side outer wall and a convex suction side outer wall that connect along a leading edge and a trailing edge. The blade also includes a first corrugated surface extending from the trailing edge to the leading edge on an outer surface of the concave pressure side outer wall, and/or a second corrugated surface extending from the trailing edge to the leading edge on an outer surface of the convex suction side outer wall. The blade acts to reduce flow velocity losses associated with wake mixing by accelerating the mixing process from the source of the wake to minimize inflated unsteady mixing that occurs within a downstream blade row.