Acoustic Nozzle Design for Gas Turbine Inlet Bleed Heat
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Solution Overview
Problem
Gas turbine engines face challenges in balancing efficient high-temperature operation with reduced NOx emissions and varying operational parameters, which affect compressor inlet systems and emissions control.
Innovation Solution
An acoustic nozzle design for inlet bleed heat systems using compressor discharge air, featuring an outer casing, acoustic attenuation medium, exit apertures, and a reduced flow area to reduce energy and noise, while stabilizing the flow and expanding pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If compressor discharge air is bled and recirculated to the compressor inlet for heating, then the temperature of incoming airstream is raised, but the air density and mass flow to the gas turbine are reduced
Solution Approach 1:
The bleed air flow is divided into multiple segments through the reduced flow area sections and distributed through multiple exit apertures along the compressor inlet circumference, allowing controlled mixing at different locations to optimize both temperature rise and mass flow preservation
Solution Approach 2:
The acoustic nozzle provides different flow characteristics at different locations - the reduced flow area sections create specific pressure and velocity profiles, while the distributed exit apertures deliver heated air at optimized local mixing zones to maintain overall mass flow while achieving temperature objectives
2Use of energy by moving object
If the flow area is reduced to increase velocity and pressure, then the energy of the flow is reduced, but the noise level increases
Solution Approach 1:
The single large flow reduction is segmented into multiple smaller reduced flow area sections distributed along the nozzle length, each producing lower individual noise levels while collectively achieving the required flow energy reduction
Solution Approach 2:
The acoustic lining material acts as an intermediary between the high-velocity bleed air jet and the surrounding atmosphere, absorbing acoustic energy and converting it to heat, thereby reducing noise while the reduced flow area sections manage the flow energy
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 acoustic nozzle design effectively reduces NOx emissions, stabilizes compressor flow, and decreases noise by mixing compressor discharge air with ambient air, enhancing the operational efficiency and emissions control of gas turbine engines.
Implementation Method 1
an acoustic attenuation medium within the outer casing
Implementation Method 2
a reduced flow area positioned about the outer chamber and the air pipe for the flow of compressor discharge air
Implementation Method 3
mixing the cooler ambient air with the bleed portion of the hot compressor discharge air
Data Source
AI summary
The present application provides an acoustic nozzle for an inlet bleed heat system using a flow of compressor discharge air. The acoustic nozzle may include an outer casing, an acoustic attenuation medium within the outer casing, a number of exit apertures positioned in the outer casing, an air pipe in communication with the outer casing, and a reduced flow area positioned about the outer chamber and the air pipe for the flow of compressor discharge air.