Wind Tunnel Wake Generator with Pivoting Bars
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Solution Overview
Problem
Current wake generators in wind tunnels are limited by the creation of reverse wakes, which disrupt the flow and limit testing duration, and often require significant modifications to the tunnel, leading to inefficiencies and air leakage issues.
Innovation Solution
A wake generator design featuring a first frame member with a track having a rounded and flat side, where bars are rotatable and pivotable, minimizing reverse wakes by aligning their flat faces parallel or perpendicular to the flow direction, and utilizing a motor and sliders for controlled movement, allowing for both circular and linear motion patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rotating bar wake generator is used, then a wake can be produced, but air leakage occurs and the design is cumbersome
Solution Approach 1:
The wake generator is divided into multiple discrete bars that can be independently positioned and oriented. Each bar can be selectively deployed to create wakes at different locations, allowing the system to produce reliable wakes without requiring a complete rotating structure that would cause air leakage.
2Reliability
If a squirrel cage wake generator is used, then a wake can be produced, but reverse wakes are created that disrupt flow
Solution Approach 1:
The harmful reverse wake effect is extracted and eliminated by using individual bars that can be independently controlled. Instead of having bars that necessarily create reverse wakes when returning to starting positions, each bar can be independently retracted or positioned to minimize reverse wake formation, separating the wake production function from the reverse wake problem.
Solution Approach 2:
Instead of having bars traverse in a circular path that inevitably creates reverse wakes, the system inverts the approach by using bars that can be independently positioned and oriented. The bars can be retracted upstream of the test article before completing a full cycle, inverting the traditional continuous circular motion into a controlled, intermittent presence that eliminates reverse wakes.
3Reliability
If a traversing wake generator is used, then a wake can be produced, but testing duration is limited by bar cascade length
Solution Approach 1:
The wake generator transitions from a static or linearly traversing system to a dynamic system where bars can be independently positioned at any location around the test article. This dynamic positioning capability, combined with rotational movement, allows the bars to continuously generate wakes throughout extended testing periods without being limited by a fixed bar cascade length.
4Duration of action of moving object
If bars traverse in a circular path, then continuous wake production is possible, but velocity profiles do not match turbine engine conditions
Solution Approach 1:
Instead of using a uniform circular path for all bars, the system applies local quality by allowing each bar to be independently positioned and oriented. Bars can be placed at different radial distances and angular positions to create localized velocity profiles that accurately match specific turbine engine conditions, rather than forcing a single circular velocity pattern on all bars.
Data Source
AI summary
A wake generator for placement in a wind tunnel between a wind source and a test object for generating a predetermined wake pattern, comprising: a first frame member comprising a first track formed thereon, the first track having a rounded first side and a flat second side; a mounting plate disposed within a perimeter of the first track, the mounting plate rotatable relative to the first frame member about a first axis; and a plurality of bars slidably engaged to the mounting plate and structurally configured to traverse along the first track when the mounting plate is rotated about the first axis, where each of the plurality of bars comprises a pivotal connection allowing each of the plurality of bars to pivot about the pivotal connection when traversing along the first track, wherein the plurality of bars are parallel to the track on the second side of the wake generator.