Turbine Cooled Wall Double-Layer Serpentine Channel Design

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Solution Overview

Problem

Current cooling systems for gas turbine components face limitations in reducing temperature gradients and thermal stresses, leading to reduced lifetime due to extensive impingement cooling and thick cold walls, which are exacerbated by increasing turbine inlet parameters.

Innovation Solution

A double layered convective cooling scheme using serpentine channels with counter-current flow and preheated air to reduce temperature gradients, combined with cylindrical channels to minimize sharp corners and enhance heat transfer, optimizing cooling uniformity and reducing thermal stresses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If extensive impingement cooling with thick cold walls is used, then cooling effectiveness is improved, but temperature gradients and thermal stresses increase reducing component lifetime

Engineering Contradiction:

Improvecooling effectivenessVSAvoidcomponent lifetime

Core Design Contradiction:

TemperatureVSDuration of action of stationary object

Solution Approach 1:

The cooling system is divided into two distinct layers: a first layer of cooling channels near the hot gas side for intensive cooling, and a second layer of cooling channels near the coolant side for temperature uniformity. This segmentation allows each layer to perform its specific function optimally while working together to resolve the contradiction between cooling effectiveness and thermal stress reduction.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the wall are provided with different cooling characteristics through the two-layer system. The first layer provides intensive cooling where heat flux is highest (near hot gas), while the second layer provides gentle cooling to maintain temperature uniformity (near coolant side), creating local quality variations that address both cooling effectiveness and thermal stress concerns.

Inventive Principle:

Principle #3Local quality

2Power

If turbine inlet parameters are increased, then efficiency and power output are improved, but thermal boundary conditions worsen requiring more effective cooling

Engineering Contradiction:

Improvepower outputVSAvoidthermal boundary conditions

Core Design Contradiction:

PowerVSObject-affected harmful factors

Solution Approach 1:

The cooling problem is solved by transitioning from a single-layer cooling approach to a two-layer cooling approach, adding a dimensional aspect to the cooling system design. This dimensional change allows simultaneous optimization of both cooling effectiveness and thermal stress management, enabling the system to handle worsened thermal boundary conditions from higher turbine inlet parameters.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Temperature

If the inner side of the wall is completely surrounded by coolant, then cooling is improved, but temperature difference across the wall increases causing high thermal stresses

Engineering Contradiction:

Improvecooling performanceVSAvoidthermal stresses

Core Design Contradiction:

TemperatureVSStress or pressure

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of having the coolant side completely surround the wall (conventional approach), the system inverts the approach by placing cooling channels on both sides of the wall, with the first layer near the hot gas side and the second layer near the coolant side. This inversion allows the coolant side to contribute to cooling rather than just being a heat sink, reducing temperature differences and thermal stresses.

Inventive Principle:

Principle #13The other way round (Inversion)

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 proposed cooling scheme effectively reduces thermal stresses and extends the lifetime of turbine components by achieving uniform metal temperatures and heat transfer rates, while also offering coolant savings and adaptability to varying pressure ratios.

Implementation Method 1

a first layer of cooling channels for a coolant, said first layer having a serpentine shape

Methodology Applied

Scientific EffectHeat transfer: Convection

Implementation Method 2

reduce temperature gradients across the cooled walls and as the results thermal stresses

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 3

said outlet of each of said channels of said first layer being in fluid communication with corresponding inlet of associated channel of said second layer

Methodology Applied

Scientific EffectCounter-current heat exchange: Convection

Data Source

PatentUS10851668B2Cooled wall of a turbine component and a method for cooling this wall

Publication Date: 2020.12.01 ANSALDO ENERGIA SWITZERLAND AG

AI summary

A cooled wall of a turbine component includes a first layer of channels for a coolant arranged along a side of the wall facing to a flow of hot gas, the first layer of channels having a serpentine shape, each channel of the first layer having an inlet and an outlet; a second layer of channels for the coolant disposed further from the flow of hot gas than the first layer, each channel of the second layer having an inlet and an outlet, the outlet of each of the channels of the first layer being in fluid communication with corresponding inlet of associated channel of the second layer creating a bend for changing a direction of the coolant leaving the channel of the first layer when entering the channel of the second layer.