Pulse Combustor Decoupling Chamber for Anti-Phase Noise Reduction

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Pulsejet engines face challenges with high noise and vibration levels due to oscillating flows, which hinder their widespread implementation, especially in applications like Vertical TakeOff and Landing (VTOL) aircraft, and existing methods to operate two pulsejet engines in anti-phase reduce oscillation pressure amplitude, leading to lower thrust and efficiency.

Innovation Solution

A system using pressure and velocity sensors to detect harmonics in pulsejet engines, adjusting the fuel injection profile to minimize harmonic content and employing acoustic resonators tuned to specific frequencies to dampen undesirable oscillation modes, allowing for anti-phase operation with minimal interference and reduced noise and vibration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If two pulsejet engines are operated simultaneously in anti-phase to counter oscillating flows, then noise and vibration levels are reduced, but oscillation pressure amplitude is reduced leading to lower thrust and efficiency

Engineering Contradiction:

Improvenoise and vibration levelsVSAvoidthrust and mechanical power output

Core Design Contradiction:

Object-affected harmful factorsVSPower

Solution Approach 1:

A decoupling chamber is introduced as an intermediary component between the two pulsejet engines. This chamber allows the engines to operate in anti-phase to reduce noise and vibration while minimizing the negative impact on oscillation pressure amplitude. The decoupling chamber is designed with specific volume and flow characteristics to reduce flow resistance compared to traditional large-volume decoupling chambers, thereby maintaining higher pressure amplitude and thrust output.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention optimizes parameters of the decoupling chamber including its volume, inlet and outlet port sizes, and positioning relative to the pulsejet engines. By carefully adjusting these parameters, the system achieves anti-phase operation with minimal loss of oscillation pressure amplitude. The optimized parameters allow sufficient air intake and exhaust flow while maintaining the pressure conditions necessary for high thrust and efficiency.

Inventive Principle:

Principle #35Parameter changes

2Object-affected harmful factors

If a decoupling chamber with large volume is used to produce anti-phase operation, then oscillating flows are countered, but flow resistance increases reducing air intake and fuel combustion

Engineering Contradiction:

Improveoscillating flowsVSAvoidair intake and fuel combustion rate

Core Design Contradiction:

Object-affected harmful factorsVSProductivity

Solution Approach 1:

The decoupling chamber is designed with optimized parameters including smaller volume, appropriately sized inlet and outlet ports, and specific positioning. These parameter changes reduce flow resistance while still enabling anti-phase operation. The optimized port sizes and chamber dimensions allow sufficient air intake for combustion without creating excessive flow resistance, thereby maintaining productivity.

Inventive Principle:

Principle #35Parameter changes

3Object-affected harmful factors

If decoupling chamber is inserted between exhaust pipes to achieve anti-phase operation, then noise is reduced, but exhaust flow is impeded reducing thrust

Engineering Contradiction:

Improvenoise levelsVSAvoidthrust

Core Design Contradiction:

Object-affected harmful factorsVSForce

Solution Approach 1:

The decoupling chamber serves as an intermediary that connects the exhaust pipes of two pulsejet engines while enabling anti-phase operation. The chamber is designed with optimized outlet port size and positioning to minimize impedance to high-velocity exhaust gases. This allows the exhaust flow to maintain sufficient velocity for thrust production while the chamber facilitates the noise-reducing anti-phase operation.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 system effectively reduces noise and vibration levels by minimizing harmonic content and maintaining efficient operation of pulsejet engines, enhancing their suitability for applications like VTOL aircraft by maintaining thrust and mechanical power output.

Implementation Method 1

employing acoustic resonators tuned to specific frequencies to dampen undesirable oscillation modes

Methodology Applied

Scientific EffectAcoustic resonance: Resonance

Implementation Method 2

acoustic resonators tuned to specific frequencies to dampen undesirable oscillation modes

Methodology Applied

Scientific EffectAcoustic absorption: Acoustic Absorption

Data Source

PatentEP3587925B1Systems and methods for improving operation of pulse combustors

Publication Date: 2021.10.20 NORTH AMERICAN WAVE ENGINE CORP

Figure 1
Figure 2A
Figure 2B

AI summary

A pulse combustor system for reducing noise and/or vibration levels. The system includes a first pulse combustor including a combustion chamber, an inlet pipe, an exhaust pipe, and a first fuel injector for injecting fuel into the combustion chamber. The pulse combustor has a fundamental oscillation mode and one or more additional oscillation modes. The system includes adjustable resonator or a second pulse combustor connected to the first pulse combustor to reduce excitation of the one or more additional oscillation modes.