Variable 3D Convergent-Divergent Nozzle for Dynamic Mach Number Control
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Solution Overview
Problem
Current convergent-divergent (CD) nozzles are fixed in shape, making it difficult and costly to change the Mach number for testing, and existing 2D variable nozzles do not accurately represent real-world 3D airflow conditions, leading to improper test conditions for high-speed/hypersonic devices.
Innovation Solution
A variable 3D CD nozzle with a flexible body composed of interconnected members that can change shape through mechanisms like iris assemblies and adjustable loop assemblies, allowing for real-time adjustment of the throat area and location relative to the inlet and outlet planes, using actuators and a controller to simulate various operational conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If fixed-shape CD nozzles are used, then manufacturing is simple and reliable, but changing Mach number requires physical nozzle replacement which is time-consuming and costly
Solution Approach 1:
The nozzle throat area is made dynamically adjustable through a mechanism that moves the throat plane relative to the inlet and outlet planes. This allows continuous variation of the area ratio and Mach number without physical nozzle replacement, resolving the contradiction between adaptability and time loss.
Solution Approach 2:
The nozzle is divided into separate functional sections with the throat plane positioned on a movable carriage that can be independently adjusted. This segmentation allows the throat area to be modified while keeping the rest of the nozzle structure fixed, enabling rapid Mach number changes.
2Measurement precision
If 2D variable CD nozzles are used, then throat area can be adjusted, but they do not accurately represent real-world 3D airflow conditions
Solution Approach 1:
The invention transitions from 2D planar adjustment to 3D axisymmetric adjustment by positioning the throat plane on a circular carriage that rotates about the nozzle centerline. This creates a three-dimensional convergent-divergent geometry that accurately represents real-world airflow conditions while maintaining adjustable throat area.
Solution Approach 2:
The movable throat plane creates an asymmetric configuration during adjustment that transitions to a symmetric 3D shape when positioned correctly. This allows the nozzle to maintain accurate 3D airflow representation while providing versatile adjustment capability.
3Speed
If the throat area is reduced for high Mach numbers, then hypersonic velocities can be achieved, but the nozzle throat becomes very small and difficult to control
Solution Approach 1:
The mechanical adjustment of the throat plane is replaced with a motor-driven positioning system that uses controlled motion to adjust the throat area. This substitution makes it easier to control very small throat dimensions required for high Mach numbers while maintaining precision and repeatability.
Data Source
AI summary
A variable 3D CD nozzle includes: a flexible body defining a flow path having an inlet extending through a narrowed throat to an expanded outlet, wherein the flexible body comprises a plurality of flexible members movably interconnected together; and at least one means for changing a shape of the flexible body to change a dimension or location of the throat plane relative to at least one of the inlet plane or outlet plane. A method of changing airflow in a nozzle includes operating at least one means for changing the shape of the flexible nozzle body to change the dimension or the location of the throat plane. A method of testing an object includes placing a test object in the test region of the test cell and passing a test gas from the outlet opening of the nozzle onto the test object.