Variable-Geometry Coanda Thruster for Low-Flow Entrainment
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Solution Overview
Problem
Fixed-geometry thrusters experience significant performance degradation at lower primary fluid flow rates due to inefficient mixing and entrainment, particularly in the straight portion of the thruster, leading to reduced thrust efficiency.
Innovation Solution
A variable-geometry Coanda-type thruster with a flow controller mechanism that adjusts the cross-sectional area of primary fluid passages using shims and an actuating apparatus, allowing for optimal primary fluid introduction and entrainment even at non-ideal conditions, enhancing the Coanda effect and thrust generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If fixed-geometry thruster design is used, then manufacturing simplicity is maintained, but thrust efficiency degrades significantly at lower flow rates
Solution Approach 1:
The patent applies variable geometry to the thruster passages, allowing the cross-sectional area to change dynamically based on flow conditions. This is achieved through movable walls or adjustable components that modify the passage geometry in real-time, enabling optimal performance across a range of flow rates rather than being fixed for a single design point.
Solution Approach 2:
The invention changes the geometric parameters of the thruster passages by varying the cross-sectional area according to flow rate conditions. At lower flows, the passage area is reduced to increase velocity and maintain efficient mixing, while at higher flows the area expands to accommodate the increased flow without excessive velocity loss.
2Productivity
If variable geometry mechanism is added to adjust passage area, then thrust efficiency improves at lower flow rates, but device complexity increases
Solution Approach 1:
The variable geometry mechanism is designed to be self-regulating, using the flow conditions themselves to drive the geometric adjustment. The mechanism responds automatically to changes in flow rate without requiring external control systems, sensors, or complex actuation, thereby minimizing added complexity while maintaining thrust efficiency.
3Productivity
If primary fluid velocity is increased at lower flows, then entrainment ratio improves and thrust efficiency increases, but energy consumption increases
Solution Approach 1:
The invention changes the geometric parameters of the passage to optimize the balance between velocity and energy consumption. By adjusting the cross-sectional area, the system achieves higher velocities at lower flows when needed for efficient entrainment, while avoiding excessive energy consumption by not maintaining high velocities when flow rates are high and less velocity is required.
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 variable geometry thruster maintains high performance and increases thrust by up to 20% at lower flow rates by increasing primary fluid velocity and entrainment ratio, improving efficiency compared to fixed-geometry thrusters.
Implementation Method 1
A variable-geometry Coanda-type thruster with a flow controller mechanism that adjusts the cross-sectional area of primary fluid passages
Data Source
AI summary
A propulsion system coupled to a vehicle. The system includes a diffusing structure and a conduit portion configured to introduce to the diffusing structure through a passage a primary fluid produced by the vehicle. The passage is defined by a wall, and the diffusing structure comprises a terminal end configured to provide egress from the system for the introduced primary fluid. A constricting element is disposed adjacent the wall. An actuating apparatus is coupled to the constricting element and is configured to urge the constricting element toward the wall, thereby reducing the cross-sectional area of the passage.