Ejector Nozzle Edge Serrations for Vehicle Vacuum Systems
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing vacuum systems in vehicles with ejectors suffer from turbulence-induced pressure losses and inefficiencies, leading to reduced engine performance and increased noise levels due to the use of turbo-compressed air as the operating fluid.
Innovation Solution
The design incorporates a nozzle edge with serrations and/or undulations in the drive nozzle of the ejector, which reduces turbulence and enhances efficiency by optimizing the air flow breakaway edge, thereby improving the suction effect and reducing noise generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional smooth nozzle edge is used in the ejector, then the structure is simple and easy to manufacture, but turbulence occurs between the operating fluid and suction medium causing great pressure losses and low efficiency
Solution Approach 1:
The nozzle edge is given a specific local geometry with serrations or undulations instead of being smooth. This local structural modification creates a controlled breakaway edge that reduces turbulence and pressure losses in the mixing chamber, while the rest of the ejector structure remains conventional.
Solution Approach 2:
The nozzle edge features curved serrations or undulations rather than sharp edges. These curved geometries optimize the flow separation and reduce turbulence by creating gradual transitions in the flow field, improving mixing efficiency while maintaining manufacturability.
2Reliability
If turbo-compressed air is used as operating fluid in the ejector, then vacuum is generated for vehicle systems, but engine performance is reduced and noise levels increase
Solution Approach 1:
The nozzle edge geometry parameters (serration depth, frequency, shape) are optimized to change the flow characteristics. This improves the efficiency of converting operating fluid energy into suction effect, allowing adequate vacuum generation with reduced operating fluid flow, thereby preserving engine performance.
3Reliability
If turbo-compressed air is used as operating fluid in the ejector, then vacuum is generated for vehicle systems, but noise levels increase due to turbulence
Solution Approach 1:
The localized serrated or undulated nozzle edge structure modifies the flow separation characteristics at the critical mixing interface. This reduces turbulence intensity and noise generation from chaotic eddies, while maintaining the vacuum generation function through improved flow control.
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
This configuration increases the efficiency of the ejector and vehicle drive system while minimizing noise, allowing for weight savings and reduced complexity in noise reduction measures, resulting in a more efficient and quieter operation.
Implementation Method 1
Here, in accordance with Bernoulli's law, a dynamic pressure drop occurs. For this reason, the pressure in the flow is lower than the normal pressure.
Implementation Method 2
In the case of compressible propellants, in particular gases or vapors, the drive nozzle is frequently configured as a Laval nozzle in order to maximize the speed, and the drive jet exits at supersonic speed.
Implementation Method 3
After exit from the nozzle, shear stresses arise as a result of internal friction and turbulences in the boundary layer between the rapid operating fluid and the substantially slower suction medium. This stress brings about a transmission of momentum, with the result that the suction medium is accelerated and carried along.
Implementation Method 4
After exit from the nozzle, shear stresses arise as a result of internal friction and turbulences in the boundary layer between the rapid operating fluid and the substantially slower suction medium.
Implementation Method 5
A diffuser can be connected downstream of the mixing chamber for a further pressure rise.
Data Source
AI summary
A vehicle drive having a vacuum system for a vehicle having an internal combustion engine that is connected to a supply air line and to an exhaust air line. The vacuum system has an ejector. A propellant gas line opens into a nozzle channel of a propellant nozzle of the ejector. The nozzle channel opens into a mixing chamber of the ejector through a nozzle opening. A suction line opens into the mixing chamber and the mixing chamber on an outlet side opens directly or indirectly into a mixed gas line. The mixed gas line opens into the supply air line. The suction line is connected to a vacuum consumer, and the nozzle opening in the propellant nozzle is formed by a nozzle edge having teeth and/or corrugations.