Variable Turbine Vane Aft Rotation Axis Leakage Control

Solution Overview

Problem

Variable inlet guide vanes in gas turbines face significant aerodynamic losses due to leakage gaps between airfoils and end walls, which are exacerbated by high airfoil velocities and the structure of the turbine, where the spanwise height of the vane increases in the flow direction, leading to larger leakage areas and performance losses.

Innovation Solution

A turbine variable inlet guide vane assembly with a rotational axis located aft of the aerodynamic center of pressure, minimizing clearance gaps between the airfoil and large diameter end wall buttons, ensuring no gap forms at the trailing edge during movement, thus reducing leakage and enhancing performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If variable inlet guide vanes are used to control mass flow, then flow control capability is improved, but leakage gaps between airfoils and end walls increase causing aerodynamic losses

Engineering Contradiction:

Improveflow control capabilityVSAvoidaerodynamic losses

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The rotation axis is positioned aft of the aerodynamic center of pressure, reversing the conventional arrangement. This inversion creates a trailing edge gap that prevents hot gas leakage from entering the button region, converting the potential harm of gaps into a beneficial sealing effect

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The trailing edge gap, which would normally be harmful, is strategically positioned and sized to allow leakage flow to exit before reaching the button region. This converts the harmful leakage path into a controlled exit path that protects the button region from hot gas exposure

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Strength

If the spanwise height of the vane increases in the flow direction to accommodate turbine expansion, then structural integrity is improved, but leakage area increases leading to greater performance losses

Engineering Contradiction:

Improvestructural integrityVSAvoidperformance losses

Core Design Contradiction:

StrengthVSLoss of energy

Solution Approach 1:

The rotation axis is positioned aft of the aerodynamic center of pressure, reversing the conventional arrangement. This inversion creates a trailing edge gap that prevents hot gas leakage from entering the button region, converting the potential harm of gaps into a beneficial sealing effect

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The airfoil and button structure are designed with specific local characteristics: the button diameter and position are optimized to create an effective seal, while the airfoil geometry is tailored to maintain structural integrity. The local gap geometry at the trailing edge is specifically designed to allow leakage exit while blocking access to the button region

Inventive Principle:

Principle #3Local quality

3Force

If the rotation axis is placed through the aerodynamic center of pressure, then articulation forces are minimized, but trailing edge gaps form during vane movement causing leakage

Engineering Contradiction:

Improvearticulation forcesVSAvoidleakage

Core Design Contradiction:

ForceVSLoss of energy

Solution Approach 1:

The rotation axis is positioned aft of the aerodynamic center of pressure, reversing the conventional arrangement. This inversion creates a trailing edge gap that prevents hot gas leakage from entering the button region, converting the potential harm of gaps into a beneficial sealing effect

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The trailing edge gap is pre-positioned at the optimal location before vane movement occurs. This preliminary positioning ensures that as the vane articulates through its range of motion, the gap consistently blocks the leakage path to the button region without requiring active control or adjustment during operation

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS10208619B2Variable low turbine vane with aft rotation axis

Publication Date: 2019.02.19 FLORIDA TURBINE TECHNOLOGIES INC

AI summary

A turbine with a variable inlet guide vane assembly in which the vane airfoils extend between inner and outer buttons, and in which a center of rotation of the airfoil is located aft of an aerodynamic center of pressure of the airfoil. The trailing edge of the airfoil extends into both of the buttons such that no gap is formed between the airfoil trailing edge region and a static part of the turbine during movement of the airfoil from an opened position to a closed position.