Turbofan Bleed Supercharged Auxiliary Engine
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Solution Overview
Problem
Multi-spool gas turbine engines face issues with stall conditions when external power is used to boost the low-pressure compressor, as the increased airflow output can exceed the intake capacity of the downstream high-pressure compressor.
Innovation Solution
The system connects two gas turbine engines via an inter-engine gas path, where excess airflow from the primary engine is bled downstream of the low-pressure compressor and supplied to the secondary engine, preventing stall and supercharging it with pre-pressurized air.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If external power is used to boost the low-pressure compressor, then the low spool power is improved, but the airflow output exceeds the intake capacity of the downstream high-pressure compressor causing stall
Solution Approach 1:
The patent extracts excess airflow from the low-pressure compressor outlet by introducing a bleed port that diverts a portion of the compressed air away from the high-pressure compressor inlet. This extraction prevents overpressurization and stall conditions while allowing the low spool to operate at enhanced power levels driven by the secondary turbine engine.
Solution Approach 2:
The patent introduces an intermediary system consisting of a bleed port, intercooler, and ducting that mediates between the low-pressure and high-pressure compressor sections. This intermediary pathway allows controlled removal of excess airflow and provides intercooling, enabling the low spool boost while protecting the high-pressure compressor from stall conditions.
2Reliability
If excess airflow is bled from the low-pressure compressor, then stall is prevented, but the secondary engine requires additional components for intercooling and flow management
Solution Approach 1:
The patent merges multiple functions into the inter-engine gas path system: the bleed port serves both to prevent stall by removing excess flow and to provide pressurized air to the secondary engine; the intercooler simultaneously cools the bled air for high-pressure compressor protection and conditions air for secondary engine intake; the ducting integrates both engine airflow paths into a unified system.
Solution Approach 2:
The bled airflow serves multiple purposes: it prevents stall at the high-pressure compressor inlet by reducing mass flow, provides pressurized intake air to the secondary turbine engine, and when intercooled, provides conditioned air for potential cabin pressurization or auxiliary power functions, making the system highly versatile.
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 avoids stall conditions in the primary engine while enhancing the efficiency of the secondary engine by providing it with pre-pressurized air, effectively managing airflow and power across multiple engines.
Implementation Method 1
an inter-engine gas path disposed to receive gas flow bled from a bleed location in the first gas turbine engine downstream of the first compressor section, and to supply this gas flow to an inlet of the second gas turbine engine
Implementation Method 2
a first spool with a first compressor section
Implementation Method 3
supply this gas flow to an inlet of the second gas turbine engine
Data Source
AI summary
An aircraft gas turbine engine system comprises first and second gas turbine engines connected by an inter-engine gas path. The first gas turbine engine has a first spool with a first compressor section, and a second spool with a second compressor section downstream of and rotationally independent from the first compressor section. The second gas turbine engine is configured to provide power to at least one of the first and second spools of the first gas turbine engine. The inter-engine gas path is disposed to receive gas flow bled from a bleed location in the first gas turbine engine downstream of the first compressor section, and to supply this gas flow to an inlet of the second gas turbine engine.