Rotary Engine Pilot Subchamber Combustion Stability
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Solution Overview
Problem
Existing rotary internal combustion engines, such as Wankel engines, are not optimized in terms of combustion arrangements and characteristics, leading to inefficiencies and risks of premature ignition (detonation).
Innovation Solution
A pilot subchamber is introduced in the rotary engine's outer body, featuring an insert with a pilot fuel injector and ignition element, designed to create a stable ignition zone and reduce the risk of detonation through controlled fuel injection and ignition, with a geometry that includes a frustoconical subchamber and cooling channels to manage heat and thermal expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional combustion chamber design is used in rotary engines, then the engine structure remains simple, but combustion stability is poor and detonation risk increases
Solution Approach 1:
The combustion chamber is divided into two distinct parts: a main combustion chamber and a pilot subchamber. The pilot subchamber is defined by an insert element that creates a separate volume within the outer body. This segmentation allows for controlled pilot fuel injection and ignition in the subchamber, which stabilizes the overall combustion process and reduces detonation risk in the main chamber.
2Use of energy by moving object
If heavy fuels are used in rotary engines, then energy density increases, but combustion control becomes difficult and detonation risk increases
Solution Approach 1:
The pilot subchamber enables preliminary combustion action by injecting and igniting pilot fuel before the main fuel charge. This preliminary combustion creates a controlled ignition source that initiates stable burning of the heavy fuel in the main combustion chamber, improving combustion control and reducing detonation risk while maintaining the energy density benefits of heavy fuels.
3Temperature
If the pilot subchamber insert is positioned close to the main combustion chamber, then heat management improves, but thermal expansion may cause contact and damage
Solution Approach 1:
The insert element creating the pilot subchamber is positioned with specific clearance relative to the main combustion chamber walls. This local geometric arrangement allows for controlled thermal expansion of the insert while maintaining adequate heat transfer pathways. The frustoconical geometry of the insert provides stable positioning and manageable thermal characteristics.
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 pilot subchamber enhances combustion stability and reduces the risk of detonation by creating a controlled ignition zone, improving the overall efficiency and performance of the rotary engine, particularly when operating with heavy fuels.
Implementation Method 1
A pilot subchamber (72) is defined in the outer body (12), with an insert (34) having a pilot fuel injector (78)
Implementation Method 2
designed to create a stable ignition zone and reduce the risk of detonation through controlled fuel injection and ignition
Implementation Method 3
with a geometry that includes a frustoconical subchamber and cooling channels to manage heat and thermal expansion
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A rotary engine (10) has an outer body (12) having an insert (34) located in the peripheral wall (18) of the outer body (12) offset from the rotor cavity (20) such that a portion (65) of the peripheral wall (18) extends between the insert (34) and the cavity (20). The insert (34) has a pilot subchamber (72) defined therein and the portion of the peripheral wall (18) has at least one opening (68) defined therethrough in communication with at least one outlet opening (74) of the insert (34) and with the cavity (20).