Turbine Blade Cooling via Segmented Impingement and Film Holes

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Solution Overview

Problem

Turbine blades in gas turbines face thermal damage due to separation of thermal barrier coatings when exposed to hot gases, which reduces their heat resistance and increases the risk of damage, especially when combined with particle impact during operation.

Innovation Solution

A turbine blade design featuring a hollow airfoil portion with film cooling holes and an insert having high-density impingement cooling holes, strategically positioned to enhance cooling effects on both the suction and pressure surfaces, particularly at regions prone to coating separation, combining impingement and film cooling techniques to maintain effective cooling even if the thermal barrier coating separates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a thermal barrier coating is applied to protect the blade surface from heat, then the heat resistance of the turbine blade is improved, but the coating may separate upon impingement of hot gas or particles, reducing heat resistance and increasing thermal damage risk

Engineering Contradiction:

Improveheat resistanceVSAvoidcoating stability

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The cooling system is segmented into multiple independent cooling mechanisms: impingement cooling holes in the insert and film cooling holes in the airfoil portion. This segmentation ensures that if the thermal barrier coating separates, the underlying impingement cooling system continues to provide heat resistance, maintaining blade reliability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The insert with impingement cooling holes is positioned beforehand to provide a backup cooling mechanism. The high-density opening region is strategically located to cool areas prone to coating separation, cushioning against potential thermal damage before it occurs.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Ease of manufacture

If impingement cooling holes are distributed uniformly across the insert surface, then the manufacturing process is simplified, but the cooling effectiveness at critical regions prone to coating separation is insufficient

Engineering Contradiction:

Improveinsert manufacturing simplicityVSAvoidcooling effectiveness at critical regions

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The insert features a high-density opening region with a higher density of impingement cooling holes compared to other surface regions. This local concentration of cooling holes targets critical areas prone to thermal barrier coating separation, enhancing cooling effectiveness where most needed while maintaining overall manufacturing feasibility.

Inventive Principle:

Principle #3Local quality

3Area of stationary object

If film cooling holes are positioned downstream, then the film cooling effect covers a larger area, but the cooling effectiveness at the leading edge and upstream regions where coating separation is likely to occur is reduced

Engineering Contradiction:

Improvefilm cooling coverage areaVSAvoidcooling effectiveness at leading edge

Core Design Contradiction:

Area of stationary objectVSReliability

Solution Approach 1:

Upstream film cooling holes are positioned at the leading edge and upstream regions of the airfoil portion, performing cooling action beforehand in areas where thermal barrier coating separation is most likely to occur. This preliminary cooling ensures that critical regions are protected from the outset, preventing thermal damage before it can propagate.

Inventive Principle:

Principle #10Preliminary action

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 effectively suppresses thermal damage by ensuring continuous cooling through both impingement and film cooling mechanisms, maintaining the blade's integrity even when the thermal barrier coating separates, thereby enhancing the operational reliability of gas turbines.

Implementation Method 1

jetting cooling air from the inside of the insert via the impingement holes to the inner wall surface of the turbine blade wall

Methodology Applied

Scientific EffectImpingement cooling: Convection

Implementation Method 2

guiding cooling air from the inside of the turbine blade wall via the film cooling holes to the outer wall surface of the turbine blade wall and forming a film boundary layer of the cooling air that covers the outer wall surface

Methodology Applied

Scientific EffectFilm cooling: Boundary Layer

Data Source

PatentUS11414998B2Turbine blade and gas turbine

Publication Date: 2022.08.16 MITSUBISHI HEAVY IND LTD

AI summary

A turbine blade includes an airfoil portion having a hollow portion extending along the blade height direction and film cooling holes arranged along the blade height direction, and an insert disposed in the hollow portion along the blade height direction and having impingement cooling holes. The insert includes a first high-density opening region having a higher density of the impingement cooling holes than in other surface regions of the insert. The geometric center of the first high-density opening region is positioned on the suction side of the airfoil portion in the leading-edge-to-trailing-edge direction and on the outer side of the midpoint of the airfoil portion in the blade height direction. The film cooling holes includes upstream film cooling holes disposed in the suction surface of the airfoil portion at a position corresponding to the first high-density opening region or at a position closer to a leading edge than the position.