Axial Compressor Casing Cavity for Liquid Cooling Thermal Control
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Solution Overview
Problem
The thermal deformation of the compressor casing during rated operation of a simple cycle gas turbine differs significantly from that during intermediate cooling by spraying a large quantity of liquid drops, leading to a risk of rotor blade tip contact with the casing, which can cause damage and reduce efficiency.
Innovation Solution
A gas turbine system with an axial compressor that includes a cavity structure at the intermediate stage to control thermal expansion, using high-temperature and high-pressure compressed air to maintain an optimal rotor blade tip clearance, and employing an abradable coating to prevent blade damage, along with a control system to adjust the liquid drop spray rate and air flow to manage thermal expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If liquid drops are sprayed into the compressor for intermediate cooling, then the compression work is reduced and gas turbine efficiency is improved, but the thermal deformation of the casing changes causing rotor blade tip clearance reduction and risk of blade contact
Solution Approach 1:
The abradable coating is applied to the casing surface in advance before operation. This coating is designed to erode preferentially rather than the rotor blade, providing a safety buffer that prevents blade damage even when clearance is reduced due to thermal deformation during liquid drop spraying operations.
Solution Approach 2:
The invention changes the material parameter of the casing surface by applying a specialized abradable coating with controlled erosion characteristics. This coating has different mechanical properties than the base casing, allowing it to wear down preferentially to maintain safe clearance during thermal expansion variations caused by liquid drop cooling.
2Productivity
If the rotor blade tip clearance is designed to be optimum at rated operation, then the compressor efficiency is maximized, but the clearance varies with thermal expansion difference between rotor and casing
Solution Approach 1:
The invention accounts for thermal expansion differences between the rotor and casing by designing the clearance with consideration of temperature variations. The abradable coating compensates for the dynamic changes in clearance that occur as the rotor and casing expand at different rates during operation.
3Productivity
If the casing thermal expansion is larger than the rotor, then the tip clearance is increased reducing compressor efficiency, but if the rotor thermal expansion is excessively larger, then blade contact with casing occurs causing damage
Solution Approach 1:
The abradable coating serves as a pre-prepared cushion or buffer zone between the rotor blade and casing. When thermal expansion causes clearance reduction, this coating erodes preferentially to absorb the contact, preventing damage to the expensive rotor blade while maintaining acceptable clearance for efficient operation.
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 effectively suppresses the reduction in rotor blade tip clearance, ensuring compressor reliability and efficiency, even during rated operation with liquid drop spraying, by managing thermal expansion and preventing blade contact with the casing.
Implementation Method 1
an abradable coating is formed on the inner wall surface of the casing
Implementation Method 2
using high-temperature and high-pressure compressed air to maintain an optimal rotor blade tip clearance
Implementation Method 3
Fine liquid drops transferred into the compressor along with the air flow evaporate up to the saturated temperature at the stages as they pass through the rotor blades and the stator vanes, and then the evaporation latent heat reduces the operating fluid temperature
Implementation Method 4
the evaporation latent heat reduces the operating fluid temperature
Data Source
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AI summary
An axial compressor comprising liquid drop feed means for feeding liquid drops to an operating fluid of the compressor (1), a casing (54) for forming a flow path through which the operating fluid flows down and a plurality of stages, each of which is composed of one continuous rotor blade row (51) and one continuous stator vane row (53), the axial compressor (1) being structured so that the liquid drops evaporate inside the compressor (1), wherein the casing (54) is provided with a cavity (64) therein, and the cavity (64) is formed by an outer casing (62) and an inner casing (63) which is enclosing a periphery of the rotor blade rows (51) at the plurality of stages and forming internally a flow path of the operating fluid, and a flow path is provided for feeding the operating fluid to the cavity (64) on a downstream side of a region forming the cavity (64) of the inner casing (63).