Rocket Ejector Combined-Cycle Architecture for Low-Speed Ramjet Starts

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional ramjet engines have limited flight regimes and struggle to start at lower speeds due to insufficient air compression, necessitating the integration of ejectors, but current systems face inefficiencies and mechanical limitations.

Innovation Solution

A combined cycle propulsion system incorporating a rocket ejector positioned between the engine inlet and combustor, utilizing a rotating detonation rocket engine (RDRE) to enhance combustor pressures and optimize operation across various flight regimes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If a conventional ramjet engine operates at lower speeds, then the engine cannot generate sufficient air compression for combustion, but adding mechanical compressors increases device complexity and weight

Engineering Contradiction:

Improvestarting speedVSAvoidengine structure

Core Design Contradiction:

SpeedVSDevice complexity

Solution Approach 1:

A rocket ejector is introduced as an intermediary device between the inlet and combustor. The ejector uses rocket exhaust gases to create a low-pressure region that draws in and compresses ambient air, enabling the combustor to receive sufficiently compressed air at low vehicle speeds without requiring mechanical compressors

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system uses pneumatic principles by employing high-velocity rocket exhaust gases to drive the ejector effect. The expanding gases create pressure differentials that automatically compress and deliver air to the combustor, replacing mechanical compression with fluid dynamic compression

Inventive Principle:

Principle #29Pneumatics and hydraulics

2Adaptability or versatility

If different propulsion systems are used for different flight regimes, then each system can be optimized for its specific regime, but the overall system complexity and number of components increases

Engineering Contradiction:

Improveflight regime coverageVSAvoidpropulsion system architecture

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The rocket-based propulsion system is designed to perform multiple functions across different flight regimes. At low speeds, it operates as a rocket ejector providing air compression; at high speeds, it functions as a rocket thruster providing direct thrust, eliminating the need for separate propulsion systems for different regimes

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system dynamically adapts its operating mode based on vehicle speed. The rocket engine's thrust output and ejector effectiveness automatically adjust with changing flight conditions, allowing seamless transition between low-speed air-breathing mode and high-speed rocket mode without mechanical reconfiguration

Inventive Principle:

Principle #15Dynamics

3Loss of energy

If a rocket thruster is positioned external to the jet engine flow path, then the rocket flow can interact with jet flow without significant performance penalty, but the packaging efficiency and compactness decreases

Engineering Contradiction:

Improveperformance penaltyVSAvoidengine compactness

Core Design Contradiction:

Loss of energyVSVolume of moving object

Solution Approach 1:

The rocket ejector and combustor are merged into a single integrated flow path. The rocket exhaust gases are injected directly into the inlet flow before the combustor, combining the rocket propulsion function with the air-breathing engine function in a compact, co-located arrangement rather than separate external systems

Inventive Principle:

Principle #5Merging (Combining)

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

Enables ramjet engines to start at lower speeds and operate efficiently across a wide range of flight conditions, including subsonic to hypersonic speeds, by adjusting combustor conditions for variable trajectories and flight conditions.

Implementation Method 1

ramjets operate by compressing incoming air through the engine inlet at supersonic speeds, utilizing the engine's forward motion to achieve compression

Methodology Applied

Scientific EffectRam compression: Compression

Implementation Method 2

the rocket ejector is configured to adjustably output high-temperature gas into air in the mixing tube, wherein the high-temperature gas changes a pressure and thermal energy of the air within the mixing tube

Methodology Applied

Scientific EffectThermal energy transfer: Heating

Implementation Method 3

rotating detonation rocket engine (RDRE) which permits efficient operation across the full range of flight regimes

Methodology Applied

Scientific EffectDetonation: Detonation

Data Source

PatentUS12421920B1Multi-mode rocket-based combined cycle

Publication Date: 2025.09.23 VENUS AEROSPACE CORP

AI summary

An air breathing engine system has an engine inlet configured to receive a flow of air. A combustor is in fluid communication with the engine inlet. A rocket ejector is positioned between the engine inlet and combustor. The rocket ejector is connected to the combustor with a mixing tube. The rocket ejector adjustably outputs high-temperature gas into air in the mixing tube. The high-temperature gas changes a pressure and thermal energy of the air within the mixing tube, which can be used to optimize combustor operation, such as based on a trajectory, flight condition, or speed of an aircraft propelled by the air breathing engine system.