Circular Duct Flap Structure for Precise Low Airflow Regulation
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Solution Overview
Problem
Existing air flow regulation systems, such as blade dampers, struggle to maintain a precise and constant low flow rate across varying pressure ranges due to small angular variations of the blade, which leads to inaccuracy and difficulty in pressure measurement.
Innovation Solution
A duct with a circular flap that pivots around a perpendicular axis, featuring regulating members with cylindrical and recessed zones that reduce air passage to side channels, allowing precise control of air flow by adjusting the flap's angle, and equipped with pressure-measuring orifices to ensure accurate positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a blade damper is used to regulate air flow, then the air flow can be adjusted according to the blade angle, but the flow rate cannot be maintained constant and precise at low values across varying pressure ranges
Solution Approach 1:
The duct cross-section is segmented into multiple channels by the regulating member with recessed zones, creating distinct flow paths. This segmentation allows precise control of each channel's flow contribution, enabling accurate maintenance of low flow rates across varying pressure conditions.
Solution Approach 2:
The regulating member features zones with different properties: a cylindrical median zone for structural support and two recessed zones for flow regulation. This local differentiation allows the device to simultaneously maintain structural integrity while achieving precise flow control in specific regions.
2Reliability
If the blade angle is varied by small proportions to maintain constant low flow rate, then the flow rate can be kept constant, but the angular variation does not provide sufficient precision and pressure measurement becomes difficult
Solution Approach 1:
Instead of relying solely on angular variation of a blade, the invention introduces a radial dimension through recessed zones at specific distances from the duct wall. This dimensional change creates additional control parameters (radial position of recessed zones) that enhance measurement precision and flow control accuracy.
Solution Approach 2:
The recessed zones act as intermediaries between the regulating member and the duct wall, creating controlled lateral channels for air circulation. These intermediary structures facilitate accurate pressure measurement and improve the precision of flow rate control by providing defined flow paths.
3Quantity of substance
If the air passage section is reduced to maintain low flow rate, then the flow rate can be controlled, but the pressure measurement is disturbed by the presence of the damper
Solution Approach 1:
The invention extracts the pressure measurement function from the main duct flow by creating separate lateral channels through recessed zones. This separation allows pressure measurement to occur in a less disturbed region, reducing the interference caused by the damper's presence in the main flow path.
Solution Approach 2:
The recessed zones serve as intermediary structures that facilitate pressure measurement by creating lateral channels. These intermediaries provide a pathway for pressure equalization and measurement that is less affected by the damper's obstruction of the main duct flow.
Data Source
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AI summary
The invention relates to a system and to a method for controlling an aircraft engine starter-generator. The system comprises a transmission box (20) with a fixed gear ratio intended to be mechanically coupled to a turbine shaft (12) of the engine to allow the latter to be started, a gearbox (40) with multiple gear ratios that is mechanically coupled to a pinion of the transmission box, a starter-generator (30) mechanically coupled to a pinion of the gearbox, and means for instigating a change in gear ratio of the gearbox according to the mode of operation of the starter-generator.