Combustor Purge Orifice Layout for Swirler Gap Hot Gas Blocking
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Solution Overview
Problem
The radial shifting of fuel nozzle/swirler assemblies in gas turbine engines leads to larger gaps, increasing the risk of hot combustion gases being ingested into these gaps, causing thermal distress to the swirler and dome-deflector structure.
Innovation Solution
The implementation of purge orifices that provide additional airflow to the circumferential gap between the swirler and dome structure, adjusting their blockage based on the radial shift of the fuel nozzle/swirler assembly to maintain consistent total airflow and prevent hot gas ingestion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If fuel nozzle/swirler assemblies are allowed to radially shift, then ease of operation is improved, but the gap between the swirler and dome structure increases allowing hot gas ingestion
Solution Approach 1:
A purge air system is introduced as an intermediary substance between the hot combustion gases and the swirler assembly. The purge air flows through cooling holes in the dome-deflector structure and along the swirler assembly, creating a protective barrier that prevents hot gas ingestion while allowing the swirler to radially shift. This mediator substance (purge air) resolves the contradiction by blocking the harmful effect without restricting the operational movement.
Solution Approach 2:
The invention uses pneumatic flow (purge air) to solve the problem of hot gas ingestion. Compressed air is directed through cooling holes and along the swirler assembly to create a protective airflow barrier. This pneumatic approach allows the swirler to move radially while the air flow continuously prevents hot gas from entering the gap, resolving the contradiction between movement capability and protection from harmful factors.
2Reliability
If purge airflow is increased to prevent hot gas ingestion, then reliability is improved, but use of energy increases
Solution Approach 1:
Instead of increasing purge airflow uniformly across the entire dome structure, the invention applies purge air locally at specific cooling holes positioned around the swirler assembly. The purge air is directed precisely where needed - along the gap between the swirler and dome - to prevent hot gas ingestion. This localized approach improves reliability by protecting critical areas while minimizing overall energy consumption compared to a full-system purge approach.
Solution Approach 2:
The invention changes the parameters of the purge air system by controlling the flow rate and distribution through multiple cooling holes. Rather than using high-volume uniform purge air, the system optimizes the flow parameters to provide adequate protection with lower overall air consumption. The purge air parameters are adjusted to match the local requirements for preventing hot gas ingestion, resolving the contradiction between reliability and energy use.
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
Prevents the ingestion of hot combustion gases into the larger gaps by ensuring a consistent purge airflow, thereby protecting the swirler and dome-deflector structure from thermal damage.
Implementation Method 1
The heat shield may also include cooling holes to allow compressed air to flow therethrough to provide cooling to the hot side of the heat shield
Implementation Method 2
the plurality of purge orifices are arranged to provide a purge airflow to the circumferential purge cavity... the dome-deflector structure increases blockage of at least one purge orifice on the second side and decreases blockage of at least one purge orifice on the first side to prevent the ingestion of the hot combustion gases into the circumferential purge cavity
Data Source
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AI summary
A combustor (26) for a gas turbine engine (10) includes a dome-deflector structure (56) and a fuel nozzle-swirler assembly (58) having a mounting wall (130, 130a, 130b) with a plurality of purge orifices (132, 132a, 132b, 160, 206, 208, 230, 234, 238, 248, 250, 252, 254, 256, 258) extending therethrough. The fuel nozzle-swirler assembly (58) is mounted to the dome-deflector structure (56) and defines a circumferential purge cavity (150). The purge orifices (132, 132a, 132b, 160, 206, 208, 230, 234, 238, 248, 250, 252, 254, 256, 258) provide a purge airflow (82c) to the circumferential purge cavity (150). In a first state, when a radial height (174) of the circumferential purge cavity (150) is constant, the dome-deflector structure (56) overlaps a portion of the purge orifices (132, 132a, 132b, 160, 206, 208, 230, 234, 238, 248, 250, 252, 254, 256, 258) to block a portion of each purge orifice (132, 132a, 132b, 160, 206, 208, 230, 234, 238, 248, 250, 252, 254, 256, 258), and, in a second state when the fuel nozzle-swirler assembly (58) is radially shifted, the dome-deflector structure (56) increases blockage of at least one purge orifice (132, 132a, 132b, 160, 206, 208, 230, 234, 238, 248, 250, 252, 254, 256, 258) on a second side (180) of the circumferential purge cavity (150), and reduces blockage of at least one purge orifice (132, 132a, 132b, 160, 206, 208, 230, 234, 238, 248, 250, 252, 254, 256, 258) on a first side (178) of the circumferential purge cavity (150).