Tangential On-Board Injector Particle Separation
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Solution Overview
Problem
Gas turbine engines face particle accumulation issues, leading to durability problems and clogging due to the inability to reject small particles in the fan and compressor stages, which can collect near the tangential on-board injector (TOBI), affecting airflow and engine performance.
Innovation Solution
A tangential on-board injector design featuring an inlet extension that forces airflow to change direction by at least 90°, a purge cavity to expel large particles, and a separator to separate airflow into distinct paths for effective particle filtration and cooling air supply to gas turbine components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If particles are not rejected in fan and compressor stages, then small particles are present in secondary flow system and accumulate near TOBI, but this leads to particle accumulation and potential clogging in the TOBI
Solution Approach 1:
The injector structure is segmented into multiple functional zones: an inlet extension with 90° turn, a curved passageway, a purge cavity, and a separator. Each segment performs a specific particle separation function, allowing progressive filtration without requiring a completely separate particle rejection system
Solution Approach 2:
The inlet extension acts as an intermediary element that forces airflow to turn 90° before entering the main passageway. This intermediate directional change creates centrifugal effects that separate particles from the air stream without requiring direct intervention from upstream fan or compressor stages
2Object-affected harmful factors
If inlet extension forces airflow to turn 90°, then particles are prevented from entering TOBI, but this increases device complexity
Solution Approach 1:
Instead of trying to filter particles through traditional filtration methods, the design inverts the approach by using directional flow changes and centrifugal forces to naturally separate particles from the air stream. The 90° turn and curved passageway exploit particle inertia to achieve separation without complex filtering mechanisms
Solution Approach 2:
The curved passageway and 90° angled inlet extension create centrifugal effects that exploit the difference between air and particle response to curved flow paths. This curvature-based separation is more space-efficient and simpler than linear filtration approaches
3Object-affected harmful factors
If purge cavity is added to expel large particles, then particle removal is improved, but device complexity increases
Solution Approach 1:
The purge cavity extracts and removes large particles from the airflow path before the air enters the main cooling passages. By taking out the harmful particles at an early stage in the flow path, the remaining air is cleaner without requiring extensive downstream filtration
Solution Approach 2:
The purge cavity is nested within the overall injector structure, utilizing the existing curved passageway geometry. The cavity is positioned to intercept particles that follow the curved flow path, creating a compact nested arrangement rather than adding a separate external particle removal system
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 design enhances particle separation and airflow supply, preventing particle entry into the engine, ensuring clean air for cooling components and improving engine durability by filtering particles before they reach critical areas.
Implementation Method 1
the inlet extension forces the airflow to turn at least 90° prior to entering the passageway of the body
Implementation Method 2
a purge cavity configured along the air passageway of the body, the purge cavity configured such that large particles in an airflow through the passageway will enter the purge cavity
Implementation Method 3
a separator located at the exit of the body, the separator configured to separate an airflow flowing through the air passageway into a first flow path and a second flow path
Data Source
Figure 1A
Figure 1B~1C
Figure 2A
AI summary
A tangential on-board injector for a gas turbine engine is provided. The tangential on-board injector includes a body (212) having an entrance (215) and an exit (217). The body has a curved shape and defines an air passageway between the entrance (215) and the exit (217). An inlet extension (220) is connected to the entrance (215) of the body (212), the inlet extension (220) extending from the body (212) and having an inlet (222) configured to force air to change direction when entering the inlet (222) of the inlet extension (220).