Upstream Optical Window Turbulators for Even Boundary-Layer Heat Transfer
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Solution Overview
Problem
Conventional methods fail to effectively minimize thermal gradients across airborne optical windows, leading to degradation in optical performance due to the transition of the boundary layer from laminar to turbulent, and are not economically viable.
Innovation Solution
A system with turbulators is implemented on the exterior surface of a vehicle's window compartment to induce turbulence, using an array of staggered turbulator elements that protrude from the surface upstream of the window to disrupt the laminar boundary layer, promoting even heat transfer and reducing thermal gradients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the boundary layer transitions from laminar to turbulent over the window, then heat transfer coefficient increases, but thermal gradient increases causing optical performance degradation
Solution Approach 1:
The turbulator elements are positioned upstream of the window to preliminarily disrupt the laminar boundary layer before it reaches the window surface. This preliminary action prevents the adverse effect of laminar-to-turbulent transition over the window, maintaining more uniform heat transfer and reducing thermal gradients across the optical window.
2Reliability
If conventional methods are used to control boundary layer, then optical performance is maintained, but thermal gradients are not effectively minimized and economic viability is poor
Solution Approach 1:
The turbulator system is segmented into multiple discrete turbulator elements arranged in arrays on the compartment exterior. This segmentation allows for simpler manufacturing and installation compared to conventional methods, while effectively controlling the boundary layer to maintain optical performance and reduce thermal gradients.
3Temperature
If turbulators are placed on the compartment exterior, then boundary layer turbulence is induced and heat transfer is promoted, but device complexity increases
Solution Approach 1:
The turbulator elements on the compartment exterior passively induce turbulence in the boundary layer through their geometric configuration alone, without requiring active control systems, power sources, or complex mechanisms. The structure serves its own function of promoting heat transfer and reducing thermal gradients.
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 turbulator system effectively reduces thermal gradients across the vehicle's surface, enhancing optical performance and maintaining economic viability by stabilizing the boundary layer and promoting consistent heat transfer.
Implementation Method 1
at least one turbulator (110) on a side upstream (112) of the window (104) positioned to induce turbulence over the entirety of a boundary layer of the fluid flowing past the window (104) for even heat transfer between the fluid and the window (104)
Implementation Method 2
induce turbulence over the entirety of a boundary layer of the fluid flowing past the window
Implementation Method 3
even heat transfer between the fluid and the window (104)
Data Source
Figure 1
Figure 1a~1b
Figure 2a~2b
AI summary
A system (100) for controlling turbulence of fluid (102) flowing past a window (104) includes an imaging device compartment (105) defining an interior and an exterior separated by a window (104), wherein the window encloses at least a portion of the interior, wherein the exterior includes at least one turbulator on a side upstream of the window positioned to induce turbulence over the entirety of a boundary layer of the fluid flowing past the window (104) for even heat transfer between the fluid and the window (104).