Axial Compressor Turboshaft Bypass Layout for Particulate Control

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Solution Overview

Problem

Turboshaft engines face limitations in temperature and specific fuel consumption due to small titanium alloy compressors, and ingestion of particulate matter degrades turbine airfoils, while existing systems increase parasitic power draw and degrade performance.

Innovation Solution

A turboshaft engine design incorporating a primary and secondary bypass system with a secondary burner to manage airflow and particulate separation, utilizing a nickel material for the high-pressure compressor and variable pitch vanes to control exhaust, reducing thermal stress and improving particulate capture.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If a small radial compressor made of titanium alloy is used, then the compressor can operate at high speeds, but the compressor temperature is limited to about 755.37 K

Engineering Contradiction:
Improvecompressor speedVSAvoidcompressor temperature
Core Design Contradiction:
SpeedVSTemperature

Solution Approach 1:

The patent changes the material parameter from titanium alloy to nickel-based superalloy, which enables the compressor to operate at higher temperatures (beyond 755.37 K) while maintaining high-speed capability. This material substitution fundamentally alters the thermal limits of the compressor system.

Inventive Principle:
Principle #35Parameter changes

2Power

If the turboshaft engine is sized for maximum rated power, then power output is maximized, but specific fuel consumption increases reducing available range

Engineering Contradiction:
Improvepower outputVSAvoidspecific fuel consumption
Core Design Contradiction:
PowerVSUse of energy by moving object

Solution Approach 1:

The patent implements variable pitch vanes that can be adjusted dynamically to optimize engine performance across different operating conditions. This dynamic adjustment allows the engine to maintain high efficiency at various power levels, reducing specific fuel consumption while preserving maximum power capability.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The variable pitch mechanism changes the geometric parameter of the vanes to optimize airflow and combustion efficiency across different power settings, enabling the engine to achieve better fuel economy without sacrificing peak power output.

Inventive Principle:
Principle #35Parameter changes

3Object-affected harmful factors

If an inlet particle separation system is added, then particulate matter ingestion is reduced, but parasitic power draw from the turboshaft engine increases

Engineering Contradiction:
Improveparticulate ingestionVSAvoidparasitic power draw
Core Design Contradiction:
Object-affected harmful factorsVSLoss of energy

Solution Approach 1:

The patent extracts the particle separation function from the main engine airflow path by implementing a bypass system. Clean air is separated off before the compressor, allowing particle removal without diverting power from the main turbine, thus reducing parasitic power draw while maintaining effective particulate filtration.

Inventive Principle:
Principle #2Taking out (Extraction)

4Device complexity

If fine particles are not captured, then the system remains simple, but downstream turbine airfoils are degraded

Engineering Contradiction:
Improveparticle capture system complexityVSAvoidturbine airfoil integrity
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent performs particle separation in advance, before the air enters the compressor and turbine sections. By removing particles upstream, the system protects downstream turbine airfoils from degradation without requiring complex protection mechanisms in the turbine itself, thus maintaining system simplicity while ensuring reliability.

Inventive Principle:
Principle #10Preliminary action

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 achieves lower specific fuel consumption and extends turbine component life by capturing fine particulates, while enabling power output beyond maximum continuous power without increasing thermal stress.

Implementation Method 1

A secondary bypass is located in the core section and is configured to divert a portion of a core airflow of the core section around the main combustor and the main turbine to the power turbine

Methodology Applied
Scientific EffectFluid flow:

Implementation Method 2

A primary bypass is fluidly connected to the inlet and the outlet. The primary bypass directs a portion of an airflow entering the inlet around the core section to the outlet

Methodology Applied
Scientific EffectFluid flow:

Implementation Method 3

A secondary burner is located in the secondary bypass

Methodology Applied
Scientific EffectCombustion: Combustion

Data Source

PatentEP4086447B1Turboshaft engine with axial compressor
Publication Date: 2026.03.25 RTX CORP
  • EP4086447B1 patent drawingFigure 1
  • EP4086447B1 patent drawingFigure 2

AI summary

A turboshaft engine (10) includes a core section (100) extending between an inlet (12) and an outlet (14) of the turboshaft engine (10). The core section (100) includes a compressor (18, 26), a main combustor (44), and a main turbine (20, 28), such that combustion products from the main combustor (44) drives rotation of the turbine (20, 28) and the compressor (18, 26). A power turbine (46) is fluidly connected to the main turbine (20, 28) and driven by exhaust (42) from the main turbine (20, 28). A primary bypass (40) is fluidly connected to the inlet (12) and the outlet (14). The primary bypass (40) directs a portion (38) of an airflow (40) entering the inlet (12) around the core section (100) to the outlet (14). A secondary bypass (56) is located in the core section (100) and is configured to divert a portion (68) of a core airflow (42) of the core section (100) around the main combustor (44) and the main turbine (20, 28) to the power turbine (46).