Rotary Engine Fluid Injection Cooling for Auto-Ignition Control
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Solution Overview
Problem
Rotary engines face challenges in maintaining combustion stability under lean conditions, particularly when using alternative fuels like hydrogen and liquified natural gas, which are prone to auto-ignition due to high compression ratios.
Innovation Solution
A rotary engine design with a pilot subchamber and a main injector system that allows separate fuel and fluid injection into the combustion chamber, including a controller to manage fuel and water injection to prevent auto-ignition, using a dual-needle injector for simultaneous fuel and water delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high compression ratios are used to improve engine efficiency, then power output increases, but auto-ignition risk increases
Solution Approach 1:
The combustion chamber is segmented into a main chamber and a pilot subchamber. The pilot subchamber receives a separate pilot fuel injection and creates a localized high-temperature zone that controls ignition timing, preventing uncontrolled auto-ignition in the main chamber while allowing high compression ratios for efficiency.
Solution Approach 2:
Pilot fuel is injected into the pilot subchamber before main fuel injection into the combustion chamber. This preliminary action creates a controlled ignition source that prevents premature auto-ignition of the main fuel charge, enabling the use of high compression ratios without losing control of the combustion process.
2Loss of energy
If lean fuel-air mixtures are used to improve fuel efficiency, then fuel consumption decreases, but combustion stability deteriorates
Solution Approach 1:
The pilot subchamber creates a localized region with different mixture quality compared to the main chamber. The pilot fuel injection creates a rich, stable combustion zone that provides reliable ignition kernels, while the main chamber can operate with lean mixtures for fuel efficiency without sacrificing overall combustion stability.
3Object-generated harmful factors
If alternative fuels like hydrogen and LNG are used to reduce emissions, then environmental friendliness improves, but auto-ignition tendency increases
Solution Approach 1:
The pilot subchamber acts as an intermediary mechanism that mediates between alternative fuels with high auto-ignition tendency and the combustion process. By providing a controlled ignition source through pilot fuel injection, the system can use environmentally friendly alternative fuels while preventing uncontrolled auto-ignition through the staged combustion approach.
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 solution effectively controls combustion by preventing auto-ignition, reduces the risk of pre-ignition, and allows for the use of environmentally friendly fuels while minimizing the size of cooling systems, enhancing engine efficiency and reducing emissions.
Implementation Method 1
injecting a fluid (e.g., water) into the combustion chamber to cool the air-fuel mixture and prevent auto-ignition
Implementation Method 2
igniting a pilot injection of fuel in the pilot subchamber to ignite the main injection of fuel
Data Source
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AI summary
A rotary engine (10), has: an outer body (11) defining a rotor cavity (14); a rotor (20) within the rotor cavity (14), the outer body (11) and the rotor (20) defining a combustion chamber (24); a pilot subchamber (30) defined by the outer body (11) and having an outlet (32) communicating with the rotor cavity (24); a pilot injector (40) having a pilot tip (41) in communication with the pilot subchamber (30); a main injector (50) having a tip (50A) in communication with the rotor cavity (24), the main injector (50) having a fuel inlet fluidly connected to a fuel source (S1), a fluid inlet fluidly connected to a fluid source (S2), and an injector outlet in fluid communication with the rotor cavity (24) independently of the pilot subchamber (30), the main injector (50) having: a fuel-injection configuration in which the main injector (50) connects the fuel source (S1) to the combustion chamber (24); and a fluid-injection configuration in which the main injector (50) connects the fluid source (S2) to the combustion chamber (24).