Gas Turbine Case Cooling via Recessed Channel and Flow Jacket
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Solution Overview
Problem
The increasing temperature of compressed air in gas turbine engines exceeds the creep and strength limits of current combustor case materials, necessitating the use of high-temperature materials like nickel-based alloys, which increases production and maintenance costs.
Innovation Solution
A gas turbine case with a recessed channel portion and an outer flow jacket that forms an enclosed cooling passage along the outer case surface, allowing for the circulation of cooling air to reduce temperatures, thereby extending the use of lower-strength materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the temperature of compressed air is increased to improve compressor efficiency and compression ratio, then the compression ratio and compressor efficiency are improved, but the case material exceeds its creep and strength limits
Solution Approach 1:
The case is segmented into multiple functional zones: an inner structural case portion and an outer cooling jacket portion. The cooling jacket is divided into inlet and outlet sections with internal passages that segment the thermal management function from the structural support function, allowing the case to withstand higher compression temperatures without exceeding material strength limits.
Solution Approach 2:
A cooling jacket acts as an intermediary thermal management system between the compressed air and the case material. This intermediary structure with internal cooling passages removes excess heat before it reaches the case material, protecting it from thermal overload while allowing the compressed air to maintain high temperature for improved compression ratio.
2Temperature
If high-temperature materials like nickel-based alloys are used to maintain case strength at high temperatures, then the case can withstand higher temperatures, but production and maintenance costs increase
Solution Approach 1:
The thermal management function is extracted from the case material itself and placed into a separate cooling jacket system. This allows the case to be made from conventional, cost-effective materials while the cooling jacket handles the thermal protection, avoiding the need for expensive high-temperature materials like nickel-based alloys in the main case structure.
Solution Approach 2:
The cooling jacket serves as a replaceable, cost-effective thermal management component that protects the main case. Rather than requiring expensive high-temperature materials for the entire case assembly, the system uses a separate, more economical cooling jacket that can be manufactured and maintained at lower cost.
3Ease of manufacture
If conventional materials are used for the case to reduce costs, then production costs are reduced, but the case cannot withstand the high temperatures of compressed air
Solution Approach 1:
Cooling air is introduced through inlet passages before the hot compressed air contacts the case material. This preliminary cooling action removes excess heat from the compressed air and prevents thermal overload of the case material, allowing conventional materials to maintain their integrity at operating temperatures.
Solution Approach 2:
A pneumatic cooling system using cooling air flow through internal passages within the cooling jacket provides thermal management. This fluid-based cooling mechanism efficiently removes heat from the compressed air and protects the case material, enabling the use of conventional materials while maintaining case integrity at high operating temperatures.
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 cooling structure effectively manages high temperatures without requiring high-temperature materials, reducing production costs and maintaining the compressor/combustor case's integrity, while allowing for conventional fasteners and minimizing thermal mismatch and leakage.
Implementation Method 1
The cooling structure effectively manages high temperatures without requiring high-temperature materials, reducing production costs and maintaining the compressor/combustor case's integrity
Implementation Method 2
An outer flow jacket is attached to the outer case surface and extends over the channel portion to define an enclosed cooling passage along the outer case surface. The inlet passage supplies cooling air from a source of air for effecting cooling of the case
Data Source
AI summary
A gas turbine case is provided including an outer case surface, and a channel portion formed as a recessed area extending radially inwardly into the outer case surface. The channel portion extends about a circumference of the case. An outer flow jacket is attached to the outer case surface and extends over the channel portion to define an enclosed cooling passage along the outer case surface. At least one inlet passage and at least one outlet passage are provided in fluid communication with the enclosed cooling passage to convey air to and from the cooling passage.