Arcuate Deflector for Aero-Optical Flow Control

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Solution Overview

Problem

Existing solutions for controlling fluid flow over optical instruments in freestream flow fields are invasive, complex, and limit the operational orientations of the instruments, leading to beam aberrations and reduced performance due to turbulent flow-induced density fluctuations.

Innovation Solution

A method and apparatus that split the freestream flow field into an aero-optical flow region over the optical instrument housing using an arcuate top surface and outer perimeter, maintaining a smooth, impermeable boundary layer for reduced density gradients and improved beam quality across various angular orientations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional solutions (openings, channels, active flow control) are used to address unfavorable near-field flow, then beam quality is improved, but device complexity and structural alterations increase

Engineering Contradiction:
Improvebeam qualityVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent employs a curved deflector surface with specific radius of curvature to guide flow smoothly over the optical instrument housing. This curved geometry creates a favorable pressure gradient that maintains attached flow and prevents turbulence, thereby improving beam quality without requiring complex active control systems or structural modifications to the vehicle

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Reliability

If active control with static jets of fluid is used, then flow is influenced, but viewing angles of the instrument are limited

Engineering Contradiction:
Improveflow control effectivenessVSAvoidviewing angles
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The deflector is designed as a movable component that can rotate to maintain the favorable pressure gradient regardless of the instrument's orientation. This dynamic adjustment capability allows the system to maintain effective flow control across a wide range of viewing angles, eliminating the angular limitations of static jet systems

Inventive Principle:
Principle #15Dynamics

3Reliability

If openings or channels through the vehicle housing are created, then near-field flow is improved, but structural integrity and vehicle design are compromised

Engineering Contradiction:
Improvenear-field flow qualityVSAvoidstructural alterations
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent introduces an external deflector as an intermediary component that modifies the flow field without requiring any openings or channels in the vehicle housing. This deflector acts as a flow conditioning element that attaches to the existing housing structure, improving near-field flow quality while preserving structural integrity and avoiding complex manufacturing modifications

Inventive Principle:
Principle #24Intermediary (Mediator)

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 effectively mitigates beam aberrations and enhances the Strehl ratio, allowing for improved image quality and operational flexibility of optical instruments by maintaining an aero-optical flow region over the housing, regardless of its angular rotations.

Implementation Method 1

maintaining a smooth, impermeable boundary layer for reduced density gradients

Methodology Applied
Scientific EffectBoundary layer: Boundary Layer

Implementation Method 2

split the freestream flow field into a first flow field that is at least partially above the apparatus and window and a second flow field that is at least partially under the apparatus and around the housing

Methodology Applied
Scientific EffectFlow separation: Flow Separation

Data Source

PatentEP2927114B1Apparatus and methods for passive control of flow
Publication Date: 2019.02.06 GENERAL ATOMICS AERONAUTICAL SYSTEMS INC
  • EP2927114B1 patent drawingFigure 1
  • EP2927114B1 patent drawingFigure 2
  • EP2927114B1 patent drawingFigure 3A~3B

AI summary

Apparatus and methods are disclosed for controlling the flow of a fluid over the window (615) of an optical instrument housing (600) in a freestream flow field (700). For example, the flow upstream of the housing may be split by an arcuate surface (510) having a curvature to create a flow region (715) over the window that is conducive to successful operation of the instrument. The flow region may be maintained for various rotations of the housing about yaw, pitch, and roll axes. The disclosed features in some embodiments induce flow regions with reduced spatial and temporal density gradients of the flow over the window.