Multipoint Injector Swirl Chamber Design for Uniform Spray
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Solution Overview
Problem
Conventional multipoint injectors face challenges in achieving improved spray patternation and manufacturability, particularly in fuel injection applications where high pressure is not feasible, leading to larger droplets and energy wastage in air-blast methods.
Innovation Solution
A multipoint injector design featuring a nozzle body with radially outward swirl chambers and tangential feed slots inducing swirl, aligned with injection orifices to produce a swirling spray, enhancing atomization and spray distribution, along with a nozzle tip and braze joints for improved assembly and thermal management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high liquid supply pressure is used to achieve high flow rates, then flow rate is improved, but energy consumption increases and system complexity increases
Solution Approach 1:
The single large flow path is segmented into multiple smaller injection orifices (e.g., 6 orifices arranged in 2 rows of 3). This segmentation allows the total flow rate to be maintained while each individual orifice operates at lower pressure, reducing overall energy consumption and avoiding the need for excessively high supply pressure.
Solution Approach 2:
The injection system transitions from a single-point injection to a multi-point arrangement in three-dimensional space. The six injection orifices are positioned at different locations and angles, creating a distributed injection pattern that achieves high flow rate without requiring high pressure in any single flow path.
2Productivity
If orifice diameter is enlarged to achieve high flow rates, then flow rate is improved, but droplet size increases and atomization quality deteriorates
Solution Approach 1:
The total flow is divided into multiple smaller streams through separate injection orifices. Each orifice produces fine droplets due to its small diameter, and the collective output of multiple orifices achieves the required total flow rate without sacrificing atomization quality.
Solution Approach 2:
Instead of using one large orifice, the system employs multiple smaller orifices that collectively provide the necessary flow capacity. This partial action approach (multiple small injections) exceeds the capability of a single large orifice in terms of atomization quality while maintaining equivalent or superior total flow rate.
3Manufacturing precision
If air-blast method is used to atomize sprays, then atomization quality is improved, but energy wastage increases due to pressure drop across trim orifice
Solution Approach 1:
The trim orifice component is removed from the system. Instead of using a separate trim orifice to calibrate flow, the injection orifices themselves are precision-manufactured to the required dimensions, eliminating the energy-wasting pressure drop across a trim orifice while maintaining accurate flow calibration.
Solution Approach 2:
The injection orifices serve dual functions: they both calibrate the flow rate and perform the atomization function. This self-service approach eliminates the need for a separate trim orifice calibration stage, reducing energy losses and simplifying the system.
4Productivity
If multiple injection points are employed to disperse flow, then flow management is improved, but spray patternation quality deteriorates
Solution Approach 1:
Each injection orifice is specifically designed with unique characteristics including different orientation angles (e.g., 30 degrees, 60 degrees, 90 degrees relative to the axis), different positions, and potentially different diameters. This local quality variation in each injection point allows the system to achieve both good flow dispersion and superior spray patternation, as each orifice contributes differently to the overall spray pattern.
Solution Approach 2:
The arrangement of injection orifices employs asymmetric positioning and orientation. The orifices are not uniformly distributed but are strategically positioned at different angles and locations to optimize both flow dispersion and spray pattern formation, creating an asymmetric configuration that achieves superior performance.
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 design achieves a substantially uniform spray distribution and improved manufacturability, enhancing atomization efficiency and reducing energy wastage, while allowing for independent operation of injection circuits for staged fuel delivery.
Implementation Method 1
each respective swirl chamber is in fluid communication with a respective one of the feed bores through a tangential feed slot configured to convey fluid from the feed bore into the swirl chamber to induce swirl on fluids within the swirl chamber
Implementation Method 2
The air-blast method relies on the shearing effect of high velocity air to provide atomization
Data Source
AI summary
A multipoint injector includes a nozzle body defining a fluid inlet in fluid communication with a plurality of feed bores. A plurality of swirl chambers is defined radially outward from the fluid inlet of the nozzle body in fluid communication with the fluid inlet through the feed bores. A plurality of injection orifices are respectively aligned in fluid communication with the swirl chambers for issuing a swirling spray of fluid passing from each swirl chamber through each injection orifice.