Turbomachine Shroud Grooves for Tip Vortex Cancellation
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Solution Overview
Problem
In turbomachines, the gap between the rotor blade tip and the shroud leads to vortex formation on the suction side of the blade, resulting in entropy generation and performance loss due to over tip leakage and the additional component heating from hot gases.
Innovation Solution
A system with a rotor blade and shroud featuring a tip cavity defined by tip rails and a shroud with grooves along the circumferential direction, which disrupts vortex formation by creating a vortex-cancelling flow through slots and openings, reducing the gap between the blade tip and shroud.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a squealer tip wall is added to reduce the gap between airfoil tip and shroud, then the gap size is reduced, but the device complexity increases and additional heating from hot gases occurs
Solution Approach 1:
The tip floor is segmented into multiple discrete cooling holes arranged in a pattern, rather than a single continuous structure. This segmentation allows the cooling medium to be distributed effectively across the tip cavity while maintaining structural simplicity and reducing the gap between airfoil tip and shroud.
2Temperature
If cooling holes are added to the tip floor to cool the tip cavity, then the thermal management is improved, but the device complexity increases
Solution Approach 1:
The tip floor incorporates a pattern of discrete cooling holes that create a porous structure. This allows the cooling medium to pass through and cool the tip cavity effectively while maintaining structural integrity and avoiding the need for complex internal cooling channels.
3Object-generated harmful factors
If the gap between airfoil tip and shroud is reduced, then vortex formation is minimized, but manufacturing precision requirements increase
Solution Approach 1:
The cooling holes in the tip floor serve dual functions: they cool the tip cavity and simultaneously help maintain the gap clearance between the airfoil tip and shroud. The structure is self-regulating, using the cooling medium flow to sustain the desired geometric relationship without requiring external adjustment mechanisms.
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 solution effectively reduces entropy generation and improves performance by minimizing vortex formation and heat transfer, enhancing the efficiency of turbomachines.
Implementation Method 1
A system with a rotor blade and shroud featuring a tip cavity defined by tip rails and a shroud with grooves along the circumferential direction, which disrupts vortex formation by creating a vortex-cancelling flow through slots and openings
Data Source
AI summary
A system for a turbomachine includes a rotor blade configured to rotate along a circumferential direction within a casing of the turbomachine and a shroud positioned outward of the rotor blade along a radial direction. The rotor blade includes a root, a tip spaced radially outward from the root, a pressure side tip rail that extends around the tip of the rotor blade along a pressure side wall, and a suction side tip rail that extends around the tip of the rotor blade along a suction side wall. The shroud includes a radially inner surface facing the pressure side tip rail and the suction side tip rail of the rotor blade and spaced from the pressure side tip rail and the suction side tip rail of the rotor blade by a clearance gap. The shroud also includes a plurality of grooves extending continuously along the circumferential direction.