Compact Shock-Driven Combustor Reducing Run-Up Length and Pressure Drop
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Solution Overview
Problem
The existing deflagration-to-detonation transition (DDT) process in cyclic pulsed detonation combustors requires a long run-up length and results in high pressure drop and cooling, making it inefficient for practical propulsion systems.
Innovation Solution
The implementation of a shock-to-detonation transition (SDT) process using a smaller initiator chamber to generate a supersonic flame or detonation wave, which is then transitioned to a larger main chamber with a carefully positioned reflecting and shock-focusing surface, allowing the wave to propagate efficiently and reducing the run-up time and length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If internal obstacles (orifice plates or spirals) are used to reduce DDT distance, then the deflagration-to-detonation transition distance is reduced, but the pressure drop increases and the system requires cooling
Solution Approach 1:
The patent introduces a shock tube as an intermediary device that generates a shock wave to initiate detonation. This shock wave acts as a mediator that directly triggers the deflagration-to-detonation transition without requiring internal obstacles in the main combustion chamber, thereby reducing pressure drop while achieving short transition distance
Solution Approach 2:
The system is divided into two separate chambers: a shock tube for generating the shock wave and the main combustion chamber for the actual combustion process. This segmentation allows the shock tube to be optimized for rapid detonation initiation while the main chamber maintains low pressure drop for efficient combustion
2Speed
If internal obstacles are used in the chamber, then DDT occurs faster, but the run-up length increases with increasing chamber diameter
Solution Approach 1:
The shock tube serves as an external intermediary that generates a high-speed shock wave which is introduced into the main chamber. This approach decouples the DDT speed achievement from the chamber diameter, as the shock wave velocity is determined by the shock tube design rather than the main chamber dimensions
Solution Approach 2:
The invention moves the detonation initiation process from the main combustion chamber to a separate shock tube dimension. By generating the shock wave in a confined shock tube and then introducing it to the main chamber, the system achieves rapid DDT without the run-up length being constrained by the main chamber diameter
3Volume of moving object
If a smaller initiator chamber is used to generate the initial wave, then the system becomes more compact, but the wave transition to the larger main chamber becomes more complex
Solution Approach 1:
The shock tube acts as an intermediary structure that bridges the small initiator chamber and the large main combustion chamber. It provides a controlled environment for wave generation and a defined interface for wave transfer, simplifying the transition process despite the volume difference
Solution Approach 2:
The shock tube performs preliminary action by generating and conditioning the shock wave before it enters the main chamber. This pre-preparation of the detonation-initiating wave simplifies the transition process, as the wave is already in the appropriate state for effective main chamber ignition
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 approach significantly reduces the run-up time and length for detonation transition, enabling more efficient and compact cyclic detonation systems with lower pressure drop and initiation delay, facilitating the generation of thrust and power.
Implementation Method 1
at least one concave surface configured to focus a shock wave
Implementation Method 2
an initial connection section located between the first initiator chamber and the main chamber that enhances a combustion process via shock focusing and shock reflection
Implementation Method 3
an initial connection section located between the first initiator chamber and the main chamber that enhances a combustion process via shock focusing and shock reflection
Implementation Method 4
Following a successful transition to detonation, a detonation wave propagates toward an outlet of the pulse detonation combustor at supersonic speed causing a substantial combustion of the fuel and oxidizer mixture
Implementation Method 5
at least one concave surface configured to focus a shock wave
Data Source
AI summary
A system for efficiently creating cyclic detonations is provided. The system includes at least a first initiator chamber configured to generate an initial wave, at least one main chamber coupled to the first initiator chamber. The main chamber is configured to generate a main wave and to output products of supersonic combustion. The products are generated within the main chamber. The main chamber is configured to enable the main wave to travel upstream and downstream within the main chamber when the first initiator chamber is located outside the main chamber. The system further includes an initial connection section located between the first initiator chamber and the main chamber that enhances a combustion process via shock focusing and shock reflection.