Venturi Effect Endwall Treatment for Gas Turbine Compressor
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Solution Overview
Problem
Existing endwall treatments in axial flow gas turbine engines are insufficient in maintaining compressor efficiency over a wide range of operating conditions, often leading to stall and surge due to inadequate pressure gradient for air recirculation.
Innovation Solution
A gas turbine engine endwall treatment featuring a plurality of main recirculation passages with Venturi effect-producing throats, connected by second inlet passages and annular grooves, which enhance air recirculation and momentum transfer across the compressor blades.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional endwall treatments are used to recirculate air through the shroud, then compressor stall range is extended, but compressor efficiency deteriorates due to insufficient pressure gradient for air recirculation
Solution Approach 1:
The patent applies the Venturi effect by designing passages with varying cross-sectional areas (converging to a throat and then diverging), which creates a pressure gradient that drives air recirculation. This geometric parameter change enables sufficient airflow recirculation without compromising compressor efficiency, resolving the contradiction between extending stall range and maintaining efficiency.
2Reliability
If air recirculation is increased to prevent stall, then compressor reliability improves, but the pressure gradient required becomes insufficient under varying operating conditions
Solution Approach 1:
The Venturi-shaped passages with converging and diverging sections create favorable pressure gradients that enhance air recirculation. The geometric parameters (throat area, passage length, angle of convergence/divergence) are optimized to maintain sufficient pressure differential across a wide range of operating conditions, ensuring reliable compressor operation.
Solution Approach 2:
The patent utilizes fluid dynamic principles (Venturi effect) to create self-sustaining air recirculation through the shroud passages. The pressure gradient generated by the Venturi geometry naturally drives the airflow without requiring additional mechanical components, maintaining both reliability and pressure balance.
3Reliability
If endwall treatments are added to recirculate high-pressure fluid, then low momentum fluid is energized, but device complexity increases
Solution Approach 1:
The tip shroud serves multiple functions: it acts as the outer air seal, provides structural support, and incorporates the Venturi effect passages for air recirculation. By integrating the endwall treatment into the existing shroud structure rather than adding separate components, the patent achieves stall prevention while minimizing increases in device complexity.
Solution Approach 2:
The Venturi passages are strategically positioned at specific locations where low momentum fluid needs energizing, typically near the casing endwall. This localized application of the recirculation treatment optimizes its effectiveness while minimizing the overall structural complexity of the endwall assembly.
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 extends the compressor's stall range and maintains efficiency by ensuring sufficient air recirculation and momentum transfer, preventing compressor stall and surge across varying engine conditions.
Implementation Method 1
each of the main recirculation passages including a Venturi effect producing main throat disposed between a main inlet passage and a main outlet passage
Data Source
AI summary
A gas turbine engine endwall treatment includes a recirculation passages distributed circumferentially around and extending generally axially in an endwall or shroud, Venturi effect producing main throats between main inlet and outlet passages including main inlet and outlet ports respectively extending through the endwall or shroud, and main inlet ports axially aft and downstream of the main outlet ports. Second inlet passages may connect second inlet ports in endwall to main recirculation passages at or near main throats and second inlet ports. An annular groove in endwall may pass through and interconnect the second inlet ports. Two or more clustered inlet passages may extend from two or more clustered secondary inlet ports to two or more intersections of the two or more clustered inlet passages and the main recirculation passage. The main inlet and outlet ports may be spaced one or more stages apart.