Circular Pipe Flap With Lateral Channels for Precise Low Airflow
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Solution Overview
Problem
Existing airflow rate regulating devices, such as blade dampers, struggle to maintain a constant low airflow rate across varying pressure ranges due to small angular variations required and imprecise pressure measurements, which are further disrupted by the presence of the damper.
Innovation Solution
A pipe with a circular cross-section fitted with an airflow rate regulating device featuring a circular flap and regulating members with lateral airflow channels, where the flap pivots to reduce air passage primarily through these channels, allowing for precise control of airflow by adjusting the shape of the channels based on pressure range and incorporating pressure measuring means to ensure accurate measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a blade damper is used to regulate airflow, then the airflow rate can be adjusted by changing the blade angle, but the required angular variation is very small (only several degrees) to maintain constant flow rate over the pressure range, which does not allow precise maintenance of low flow rates
Solution Approach 1:
The invention divides the airflow regulation function into two independent parts: the flap angle control and the passage section control. The regulating members with lateral channels create fixed passage sections that force airflow through specific paths, while the flap only needs to provide coarse angular positioning. This segmentation allows the system to achieve precise flow control without requiring precise angular adjustments.
Solution Approach 2:
The regulating members act as intermediaries between the flap and the airflow. Instead of the flap directly controlling airflow through its edge position (as in traditional blade dampers), the regulating members with lateral channels mediate the airflow path. The flap's angular position controls which regulating members are active, and the regulating members' fixed geometry provides precise flow control, eliminating the need for precise angular positioning.
2Measurement precision
If pressure measurement is performed in the presence of a traditional damper, then the pressure can be monitored, but the measurement is disrupted by the presence of the damper, leading to imprecise pressure readings
Solution Approach 1:
The invention extracts the pressure measurement function from the airflow path by positioning pressure sensors in locations not affected by the damper structure. The sensors measure pressure in the hollow zones of the regulating members or in locations upstream/downstream of the flap, where the damper does not disrupt the pressure field. This separation allows accurate pressure measurement independent of the damper's presence.
3Quantity of substance
If the flap edge is positioned close to the inner wall to reduce air passage, then the passage section is reduced, but the required angular variation remains small, limiting control precision
Solution Approach 1:
The invention moves the airflow control from a one-dimensional edge-to-wall gap control (traditional blade damper) to a two-dimensional lateral channel control. The regulating members create lateral passages that force airflow through specific geometric paths defined by the channel shapes. This dimensional change allows the system to control the effective passage section through the geometry of the lateral channels rather than through small angular variations of the flap edge position.
Data Source
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.