Stator Vane Internal Channels for Leakage Flow Control

Solution Overview

Problem

In cantilever type stator vanes of gas turbines, leakage flows occur due to pressure differences between the back and ventral surfaces, leading to increased pressure loss when mixed with the main flow.

Innovation Solution

The stator vane incorporates internal channels that connect to a pressure source, allowing fluid to be blown or sucked through these channels to mitigate leakage flows, with channel openings strategically positioned near the leading or trailing edges to manage flow separation and leakage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a cantilever type stator vane is used with a clearance between the rotary shaft and stator vane, then the stator vane structure is simple and easy to manufacture, but leakage flow occurs from the ventral side toward the back side through the clearance causing pressure loss

Engineering Contradiction:

Improvestator vane structure simplicityVSAvoidpressure loss

Core Design Contradiction:

Ease of manufactureVSLoss of energy

Solution Approach 1:

The stator vane is divided into multiple functional regions: a ventral surface for main flow, a back surface with convex shape, and internal channels segmented along the spanwise direction. Each region performs a specific function - the internal channels actively control leakage flow while the convex back surface manages flow separation, allowing independent optimization of each segment to reduce overall pressure loss

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Internal channels are introduced as an intermediary mechanism between the ventral and back surfaces of the stator vane. These channels actively manage the leakage flow by allowing fluid exchange between the two surfaces, thereby controlling the harmful leakage flow without requiring structural changes to the rotary shaft or casing

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If air is sucked from the back surface opening to prevent flow separation, then flow comes into close contact with the back surface, but leakage flow from the ventral surface toward the back surface frequently occurs

Engineering Contradiction:

Improveflow stabilityVSAvoidpressure loss

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

Different regions of the stator vane are given different qualities and functions: the convex back surface is designed to control flow separation locally, while internal channels are strategically positioned to manage leakage flow in specific spanwise regions. This local differentiation allows the back surface to maintain flow attachment without creating excessive leakage flow conditions

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The pressure distribution parameters are actively controlled through the internal channels by connecting to pressure sources or sinks. By changing the pressure parameters within the channels, the system can suppress leakage flow while maintaining flow attachment at the back surface, dynamically adjusting to operating conditions

Inventive Principle:

Principle #35Parameter changes

3Reliability

If the back surface is convex shaped to prevent flow separation, then flow stability improves, but leakage flow generation is promoted due to pressure difference between back and ventral surfaces

Engineering Contradiction:

Improveflow stabilityVSAvoidpressure loss

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The stator vane is divided into multiple functional regions: a ventral surface for main flow, a back surface with convex shape, and internal channels segmented along the spanwise direction. Each region performs a specific function - the internal channels actively control leakage flow while the convex back surface manages flow separation, allowing independent optimization of each segment to reduce overall pressure loss

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Internal channels are introduced as an intermediary mechanism between the ventral and back surfaces of the stator vane. These channels actively manage the leakage flow by allowing fluid exchange between the two surfaces, thereby controlling the harmful leakage flow without requiring structural changes to the rotary shaft or casing

Inventive Principle:

Principle #24Intermediary (Mediator)

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 configuration reduces leakage flows and associated pressure losses by actively managing fluid flow through the channels, improving the operational stability of the compressor.

Implementation Method 1

a pressure difference is generated between the pressure source and the surroundings of the stator vane body, and a fluid flow is generated in the internal channel based on the pressure difference

Methodology Applied

Scientific EffectPressure difference: Pressure Gradient

Data Source

PatentUS11181001B2Stator vane and rotary machine

Publication Date: 2021.11.23 MITSUBISHI HEAVY IND LTD

AI summary

A stator vane is configured to guide a flow of a fluid flowing in an axial direction. The stator vane includes a stator vane body which extends in a radial direction with respect to an axis and includes a radially outer end portion which is supported by a casing and a stator vane inner circumferential surface which is an end surface facing an inside in the radial direction and faces an outer peripheral surface of a rotary shaft via a clearance, and an internal channel which is defined inside the stator vane body and includes a first end which is open on the stator vane inner circumferential surface and a second end which is connected to a pressure source having a pressure different from a pressure around the stator vane body.