Diesel Injector Hollow Spray via Vortex Cavitation
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Solution Overview
Problem
Current diesel fuel injectors face challenges in achieving stable and efficient fuel atomization due to unstable vortex cavitation, which affects the combustion and emission performance of diesel engines, and existing solutions either rely heavily on geometry-induced cavitation or aim to suppress vortex cavitation, rather than utilizing it effectively for a hollow spray structure.
Innovation Solution
A diesel fuel injector with a hollow spray structure induced by optimized vortex cavitation in the nozzle, featuring a specific geometric design including a needle valve, nozzle body, and sac chamber, which enhances and stabilizes vortex cavitation to improve fuel atomization, comprising a hemispherical or combined hemispherical and cylindrical sac chamber, converging conical spray holes, and controlled needle valve lift to maintain consistent cavitation under varying loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If geometry-induced cavitation is used to enhance spray atomization, then spray cone angle is enlarged, but cavitation damage to the nozzle is exacerbated
Solution Approach 1:
The patent converts the harmful vortex cavitation into a beneficial effect by optimizing the nozzle geometry to stabilize it. The sac chamber and converging conical spray holes are designed to control and direct the vortex cavitation, transforming it from a damaging phenomenon into a useful mechanism for enhancing spray atomization and cone angle without excessive cavitation damage.
Solution Approach 2:
The patent changes the geometric parameters of the nozzle, specifically introducing a sac chamber with optimized dimensions and converging conical spray holes with specific angles. These parameter changes modify the flow characteristics to stabilize vortex cavitation and control its position, thereby achieving enhanced spray performance with reduced cavitation damage.
2Reliability
If vortex cavitation is suppressed to avoid cavitation damage, then nozzle reliability is improved, but spray atomization performance deteriorates
Solution Approach 1:
Instead of suppressing vortex cavitation, the patent optimizes the nozzle geometry to control and stabilize it, converting it from a harmful phenomenon into a beneficial mechanism for enhancing spray atomization. The sac chamber and converging conical spray holes are designed to maintain vortex cavitation in a controlled manner, achieving both spray performance and nozzle reliability.
Solution Approach 2:
The patent modifies the geometric parameters including the sac chamber dimensions and spray hole angles to optimize vortex cavitation stability. These parameter changes enable the system to maintain controlled vortex cavitation that enhances spray atomization while preventing excessive cavitation damage, thereby achieving both reliability and performance improvements.
3Productivity
If needle valve lift is increased to improve fuel injection quantity, then fuel injection rate is enhanced, but vortex cavitation stability deteriorates
Solution Approach 1:
The patent employs the needle valve lift as a control parameter that provides feedback on the operating conditions. By optimizing the relationship between needle valve lift and vortex cavitation stability through geometric design, the system maintains stable vortex cavitation across varying injection rates. The sac chamber and spray hole geometry are configured to compensate for changes in needle valve position, ensuring consistent spray performance.
Solution Approach 2:
The patent optimizes the geometric parameters of the nozzle to create a feedback mechanism that maintains vortex cavitation stability despite changes in needle valve lift. The sac chamber dimensions and spray hole angles are designed to compensate for varying injection rates, allowing the system to maintain stable vortex cavitation while achieving high fuel injection rates.
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 optimized geometric structure of the diesel fuel injector stabilizes and strengthens vortex cavitation, resulting in improved fuel atomization and spray cone angle, enhancing combustion and emission performance while minimizing cavitation damage to the nozzle.
Implementation Method 1
the vortex cavitation is generated along the vortex core area. It has been demonstrated that compared with the turbulence inside the nozzle, the cavitation generated when fuel flows through the nozzle of the fuel injector has a more remarkable influence on the fuel atomization. In particular, the vortex cavitation can render the jet flow in the form of hollow spray, and thus greatly enlarges the spray cone angle.
Implementation Method 2
The turbulence in the nozzle causes unstable fluctuation on the surface of the fuel jet. Such small-scale disturbance amplifies the aerodynamic effect of the surrounding air and causes the breakup and atomization of the liquid jet.
Implementation Method 3
the generated cavitation bubbles will follow the fuel main flow to be sprayed out of the spray holes to trigger implosion, which leads to strong unstable disturbance, accelerating the jet breakup and atomization processes.
Data Source
AI summary
A diesel fuel injector based on a hollow spray structure induced by vortex cavitation in a nozzle, including a needle valve, a nozzle body, a plurality of spray holes, and a sac chamber. An axis of the needle valve coincides with an axis of the nozzle body. The spray holes are evenly distributed on a head of the nozzle body, and each have a converging conical structure. An inlet end of the spray hole is communicated with the sac chamber. The sac chamber consists of a hemispherical cavity and a cylindrical cavity.