Turbomachine Bleed Slide Valve for Hail Expulsion
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Solution Overview
Problem
Current compressor bleed systems in jet engines face difficulties in effectively expelling hail and preventing engine flame-out due to limited inter-flowpath height, especially in small engines, where integrating secondary-stream guide vanes into support arms complicates air expulsion.
Innovation Solution
A bleed system with a slide valve that occupies three positions – closed, intermediate, and open – allows for complete hail expulsion by controlling the bleed opening upstream and downstream of the support arms, using a flange for sealing and elastomeric or brush seals for enhanced sealing, ensuring effective hail removal and preventing engine flame-out.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the bleed opening is positioned downstream of the support arms, then the structure is simplified, but hail cannot be completely expelled and engine flame-out risk remains
Solution Approach 1:
The bleed opening is segmented into two distinct parts: a first bleed opening positioned upstream of the support arms and a second bleed opening positioned downstream. This segmentation allows independent control of each opening through the slide valve mechanism, enabling complete hail expulsion by opening both openings while maintaining structural organization through the intermediate casing.
2Length of moving object
If the inter-flowpath height is reduced for small engines, then the engine size is reduced, but air expulsion capability is compromised
Solution Approach 1:
The slide valve mechanism operates in the axial dimension to control the bleed openings, creating a three-position control system (closed, intermediate, open) that manages flow paths effectively within the limited radial space of small engines. The intermediate position with the flange provides precise control over the upstream opening while maintaining downstream opening capability.
3Loss of energy
If the slide valve is positioned to block the upstream bleed opening in intermediate position, then aerodynamic efficiency is improved, but hail expulsion capability is reduced
Solution Approach 1:
The slide valve is designed as a dynamic component with three distinct positions that can be selected based on operational requirements. In normal operation, the valve maintains aerodynamic efficiency by positioning to block the upstream opening. When hail is detected, the valve dynamically transitions to the open position to enable complete hail expulsion, and can position in intermediate mode to selectively block only the upstream opening while maintaining downstream capability.
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 system ensures complete expulsion of hail, eliminating the risk of engine flame-out and maintaining aerodynamic efficiency by strategically positioning the bleed opening and using seals to manage the air flow, particularly during low engine speeds.
Implementation Method 1
the slide valve comprises a flange which blocks off the bleed opening when the slide valve is in the intermediate position
Implementation Method 2
the slide valve is equipped with elastomeric seals or with brush seals in order to provide sealing between the slide valve and the plate
Data Source
AI summary
The bypass turbomachine comprises, between a primary flowpath (2) and a secondary flowpath (3), a structural intermediate casing (14). A bleed passage (29) allows the diversion of a portion of the gas stream toward the secondary flowpath (3), downstream of support arms (18) situated at the periphery of the intermediate casing. A bleed opening (28) emerges upstream of the support arms (18). A slide valve (22) slides between three positions, namely a closed position in which the slide valve (22) completely blocks off the bleed passage and opening, an intermediate position in which the bleed opening (28) emerging upstream of the support arms (18) is blocked off, while the bleed passage (29) for diverting a portion of the gas stream downstream of the support arms (18) is open, and an open position in which the bleed opening (28) emerging upstream of the support arms (18) and the bleed passage (29) emerging downstream of the support arms are both open.