Variable Nozzle Geometry for Uniform Rotor Tip Jet Efflux
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Solution Overview
Problem
Existing reaction jet helicopters experience turbulence, noise, and energy loss due to variations in compressed gas ejection velocity and mass flow through uniform cross-section apertures, leading to significant shear in the jet efflux.
Innovation Solution
A compressed gas ejection system with a variable cross-section design that maintains a substantially constant mass flow across the width of the ejection assembly, reducing turbulence and energy loss by using guide channels with varying heights and converging-diverging nozzles to optimize gas velocity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If uniform cross-section apertures are used for compressed gas ejection, then the structure is simple and easy to manufacture, but turbulence and energy loss increase due to velocity and mass flow variations
Solution Approach 1:
The aperture cross-section is varied locally along its length, with the height changing from a first value at the inlet to a second value at the outlet. This local variation optimizes the velocity distribution and mass flow characteristics of the ejected compressed gas, reducing turbulence and energy loss while maintaining manufacturing feasibility.
2Ease of manufacture
If uniform cross-section apertures are used for compressed gas ejection, then the manufacturing process is simplified, but noise levels increase due to shear in the jet efflux
Solution Approach 1:
The aperture height is varied locally along its length to optimize the velocity distribution of the ejected gas. This local optimization reduces shear in the jet efflux, thereby reducing noise generation while keeping the manufacturing process relatively simple.
3Loss of energy
If variable cross-section apertures are used for compressed gas ejection, then turbulence and energy loss are reduced, but the device complexity increases
Solution Approach 1:
The aperture cross-sectional parameter (height) is changed continuously or in steps from the inlet to the outlet. This parameter variation optimizes the flow characteristics, reducing turbulence and energy loss. The complexity is managed by implementing this variation in a controlled manner within the aperture geometry.
4Object-generated harmful factors
If variable cross-section apertures are used for compressed gas ejection, then noise levels are reduced, but the device complexity increases
Solution Approach 1:
The aperture height parameter is varied along its length to optimize noise reduction by minimizing shear in the jet efflux. This parameter change achieves the desired noise reduction while the complexity is kept manageable through a systematic approach to geometry design.
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 solution reduces turbulence, noise, and energy waste by ensuring a consistent mass flow and velocity distribution, enhancing the efficiency and performance of reaction jet helicopters.
Implementation Method 1
The compressed gas passage is adapted to direct compressed gas to the ejection assembly and includes guide channels which guide the compressed gas from the compressed gas supply to the ejection assembly. The height of the guide channels varies from an inboard side of the ejection assembly to an outboard side of the ejection assembly.
Implementation Method 2
A compressed gas ejection system with a variable cross-section design that maintains a substantially constant mass flow across the width of the ejection assembly, reducing turbulence and energy loss by using guide channels with varying heights and converging-diverging nozzles to optimize gas velocity.
Implementation Method 3
an engine-driven compressor produces compressed air which is ejected through ejection means such as jet nozzles at the tips of the rotor blades. This causes the rotor blades to rotate, thereby producing lift and thrust for the aircraft.
Data Source
Figure 1~2
Figure 3
Figure 4a~4b
AI summary
A compressed gas ejection assembly (10) for a rotating wing aircraft blade (2) comprises a compressed gas passage (114) adapted to allow a substantially constant mass flow through the compressed gas ejection assembly (10) across at least a portion of the width of the compressed gas ejection assembly (10).