Positive Displacement Capture Device for Pulse Detonation Engine Backflow Control
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Solution Overview
Problem
Pulse detonation engines and combustors face challenges in incorporating mechanical and fluidic valves due to the creation of strong shock waves that travel upstream, causing damage to upstream components and failing to completely prevent backflow, necessitating a device that provides 100% diodicity with minimal complexity and loading impact.
Innovation Solution
A positive displacement capture device featuring a rotor with lobes interacting with grooves in a casing, forming a least area rotor geometry that creates periodic barriers to block upstream components from downstream pressures and backflows, ensuring continuous flow with minimal pressure loss and no upstream exposure to downstream pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical flow control valves are used to prevent backflow and protect upstream components, then upstream components are protected from shock waves, but the device complexity increases due to high frequency operation requirements and costly structure
Solution Approach 1:
The patent replaces the mechanical valve system with a fluidic valve system that uses coanda jets and shock wave interactions to achieve flow control. This substitution eliminates the need for high frequency mechanical moving parts while maintaining the protective function against backflow and shock waves.
Solution Approach 2:
The invention uses fluid dynamic principles including coanda effect jets and controlled shock wave interactions to regulate flow direction and prevent backflow. The fluidic valve utilizes pneumatic/hydraulic forces rather than mechanical actuation to achieve the same protective function with reduced complexity.
2Productivity
If mechanical valves operate at high frequency to control pulse detonation flow, then flow control effectiveness is improved, but pressure waves are generated due to rapid opening and closure
Solution Approach 1:
By replacing the mechanical valve with a fluidic valve system, the invention eliminates the rapid mechanical opening and closing that generates pressure waves. The fluidic system achieves flow control through continuous fluid dynamic adjustments rather than discrete mechanical actions, thereby avoiding the generation of harmful pressure waves.
3Object-generated harmful factors
If fluidic valves are used to divert backflow and shockwave, then the strength of back pressure wave is reduced, but 100% diodicity cannot be achieved and backflow is not completely prevented
Solution Approach 1:
The fluidic valve system is segmented into multiple functional zones including coanda jet generation areas, shock wave interaction regions, and flow separation zones. This segmentation allows the system to progressively manage and control the shock wave and backflow through multiple stages, achieving both wave strength reduction and complete backflow prevention.
Solution Approach 2:
The invention introduces intermediary fluidic structures such as coanda jets and controlled shock wave patterns that act as mediators between the incoming flow and the upstream components. These intermediaries manage the energy of backflow and shock waves, redirecting them harmlessly while maintaining 100% diodicity.
4Device complexity
If positive displacement capture device uses rotor with lobes and casing with grooves to create periodic barriers, then 100% diodicity is achieved with minimal complexity, but structural loads are created by rotor rotation
Solution Approach 1:
The patent employs counterbalancing mechanisms where additional rotor elements or counterweights are positioned to offset the structural loads generated by the rotating lobes. This counterbalancing allows the positive displacement capture device to operate with minimal net force transmission to the surrounding components, maintaining simplicity while managing mechanical loads.
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 device achieves 100% diodicity, preventing upstream damage from downstream pressure spikes and maintaining consistent flow rates independent of downstream backpressure, while minimizing wear and friction through geometric design that maximizes choke and reduces physical contact.
Implementation Method 1
a positive displacement capture stage comprising a plurality of positive displacement flow devices, where each of the positive displacement flow devices contains a casing portion having a plurality of grooves formed on an inner surface of the casing portion, and a rotor portion having a plurality of lobes formed on an outer surface of the rotor portion
Implementation Method 2
The interaction of the lobes with the grooves creates a plurality of contact points between the lobes and grooves which travel around a perimeter of, and along a length of, the rotor portion as the rotor portion rotates about an axis relative to the casing portion
Data Source
AI summary
A positive displacement capture apparatus contains a plurality of positive displacement capture devices which each contain a rotor portion positioned inside a casing portion to act as a least area rotor which captures a volume and moves the volume along the length of the separator. The rotor portion contains a plurality of lobes which interact with grooves in the casing portion, such that the interaction of the lobes and grooves create barriers which capture the volume. The creation of the volume creates a flow barrier between a downstream end of the separator and an upstream end of the separator. The flow separator is coupled to a combustion portion to provide a flow of material to the combustion portion. The plurality of positive displacement capture devices are positioned, oriented and rotational timed such that eccentric loads created by the rotation of the rotor portions cancel each other out during operation.