Pulse Combustor Fuel Injector Layout for Compact Fuel-Air Mixing
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Solution Overview
Problem
Existing pulsejet engines face challenges with outward protrusion of fuel injectors, increasing physical dimensions and drag, complicating integration with airframes and thrust production.
Innovation Solution
The fuel injectors are installed along the inlet pipe axis in an axisymmetric fashion, with angled deflector plates inside the combustion chamber to deflect fuel spray towards the centerline, and a circular fuel rail supplies pressurized fuel, ensuring compactness and efficient fuel-air mixing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fuel injectors are installed at an angle to the air flow direction to facilitate fuel-air mixing, then mixing efficiency is improved, but the physical dimensions of the engine increase and drag increases
Solution Approach 1:
The fuel injector is nested within the inlet pipe structure, with the injector body positioned inside the inlet pipe and only the spray tip extending slightly outward. This nesting arrangement allows the injector to be integrated into the existing engine geometry rather than adding external protrusions, thereby maintaining compact dimensions while preserving the angled spray configuration needed for effective fuel-air mixing
Solution Approach 2:
The solution transitions from a two-dimensional projection view (where angled injectors appear to protrude outward) to a three-dimensional integrated view (where the injector is positioned within the inlet pipe volume). By utilizing the internal volume of the inlet pipe and orienting the spray axis at an angle to the airflow, the system achieves effective mixing without increasing the external footprint or drag area of the engine
2Productivity
If fuel injectors are installed at an angle to facilitate fuel-air mixing, then mixing efficiency is improved, but drag increases
Solution Approach 1:
The fuel injector is nested within the inlet pipe structure, with the injector body positioned inside the inlet pipe and only the spray tip extending slightly outward. This nesting arrangement allows the injector to be integrated into the existing engine geometry rather than adding external protrusions, thereby maintaining compact dimensions while preserving the angled spray configuration needed for effective fuel-air mixing
Solution Approach 2:
The angled spray configuration is applied locally at the injector tip where fuel injection occurs, while the main body of the injector and surrounding engine components maintain streamlined, drag-reducing contours. This localized application of angular geometry only where necessary for mixing efficiency prevents unnecessary drag increase from overall engine shape modifications
3Productivity
If fuel injectors are installed at an angle to facilitate fuel-air mixing, then mixing efficiency is improved, but integration with airframe becomes more complicated
Solution Approach 1:
The fuel injector is nested within the inlet pipe structure, with the injector body positioned inside the inlet pipe and only the spray tip extending slightly outward. This nesting arrangement allows the injector to be integrated into the existing engine geometry rather than adding external protrusions, thereby maintaining compact dimensions while preserving the angled spray configuration needed for effective fuel-air mixing
Solution Approach 2:
The inlet pipe serves multiple functions: it guides airflow into the combustion chamber, provides structural housing for the fuel injector, and maintains streamlined external contours for aerodynamic efficiency. By making the inlet pipe a multi-functional component that accommodates the angled injector internally, the system achieves effective fuel-air mixing without complicating airframe integration
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 arrangement reduces engine dimensions, simplifies integration, and enhances performance by minimizing drag and facilitating efficient fuel-air mixing.
Implementation Method 1
the spark plug or other ignition device is activated to produce a high-temperature source that ignites the fuel/air mixture. The ensuing combustion process causes a rise in the temperature and pressure of the gases inside the combustion chamber
Implementation Method 2
The high velocity of the escaping gases causes an overexpansion and negative pressure inside the combustion chamber. This negative pressure reverses the direction of the flow in the inlet and exhaust pipes
Implementation Method 3
Angled deflector plates are installed inside the combustion chamber in the fuel spray path to deflect fuel spray from the fuel injectors towards the combustion chamber centerline
Data Source
AI summary
A system and method are disclosed for improving fuel-air mixing in the combustion chamber of pulse combustors by deflecting the pressurized fuel injected from the one or more fuel injectors at a predetermined angle towards the centerline longitudinal axis of the combustion chamber.