Hydrogen Engine Piston Bowl for Pseudo-Tumble Air-Fuel Mixing
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Solution Overview
Problem
Adapting engine systems to operate on hydrogen fuel poses challenges related to combustion phasing, fuel handling, storage, lubrication, and thermal management, with insufficient mixing of hydrogen fuel with air leading to unpredictable ignition and undesired combustion forms.
Innovation Solution
A piston design with a combustion bowl featuring a center cone and reentrant bowl wall, along with a fuel injector targeting the center cone, facilitates direct injection of gaseous hydrogen, followed by impingement and squishing of fluids to create a pseudo-tumbling flow for improved mixing with air.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If gaseous hydrogen fuel is directly injected into the cylinder, then fuel delivery control is improved, but insufficient mixing with air occurs leading to unpredictable ignition
Solution Approach 1:
The combustion chamber is segmented into distinct zones including a central recess and a peripheral squish region. The fuel injector targets the central recess specifically, creating a localized fuel-rich zone that then mixes with air from surrounding regions. This spatial segmentation ensures both controlled fuel delivery and reliable mixing.
Solution Approach 2:
Different regions of the combustion chamber are given different functional qualities. The central recess serves as a fuel impingement and initial mixing zone, while the peripheral squish region provides additional air entrainment and mixing. This local differentiation ensures that fuel injection control translates into reliable overall mixing and ignition.
2Device complexity
If hydrogen fuel is injected without optimized flow patterns, then injection simplicity is maintained, but undesired combustion forms occur
Solution Approach 1:
The combustion chamber features an asymmetric design with a central recess and an offset fuel injector arrangement. The injector targets the recess at a specific angle, creating a controlled asymmetric flow pattern that promotes thorough mixing. This asymmetric geometry prevents stagnant zones and ensures uniform combustion, eliminating undesired combustion forms while maintaining injection system simplicity.
3Ease of manufacture
If conventional piston design is used, then manufacturing simplicity is maintained, but hydrogen fuel mixing efficiency is insufficient
Solution Approach 1:
The piston crown incorporates a pre-formed central recess and squish region geometry that prepares the combustion chamber for effective fuel-air mixing before the combustion event. This preliminary geometric preparation ensures that when hydrogen fuel is injected, it immediately encounters the optimized flow paths and mixing zones, achieving high mixing efficiency without complex manufacturing processes.
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
Enhances the predictability of ignition and reduces the likelihood of undesired combustion by achieving robust mixing of gaseous hydrogen fuel with air, thereby optimizing engine performance on hydrogen fuels.
Implementation Method 1
directly injecting a gaseous hydrogen fuel into the cylinder in an injection path targeting a center cone in a combustion bowl
Implementation Method 2
advancing fluids including impinged gaseous hydrogen fuel upwardly from a bowl floor along a reentrant bowl wall
Implementation Method 3
producing a combined mixing flow of the advanced fluids and the squished fluids around a flow axis extending circumferentially around the piston center axis
Data Source
AI summary
Operating an engine includes moving a piston toward a top-dead-center position in a cylinder, and directly injecting a gaseous hydrogen fuel into the cylinder in an injection path targeting a center cone in a combustion bowl of the piston. The gaseous hydrogen fuel is impinged upon an outer cone surface, and fluids advanced upwardly along a reentrant bowl wall toward a bowl throat opening. Squished fluids are advanced from a squish volume into the reentrant bowl throat, to produce a combined mixing flow of the advanced fluids and the squished fluids around a flow axis extending circumferentially around a piston center axis. Related apparatus is also disclosed.