Methods and device for mixing airflows in environmental control systems
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Solution Overview
Problem
In aircraft environmental control systems, turbulent mixing of trim air and conditioned air does not uniformly mix airflows before temperature measurement, leading to inaccurate temperature readings and inefficient use of trim air, which affects fuel burn efficiency.
Innovation Solution
A mixing device with a duct and guide vanes is positioned within the air supply duct to induce rotation of airflows, creating a helical vortex that improves mixing between the trim air and conditioned air, allowing for more accurate temperature measurements and precise trim air injection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If turbulent mixing is used to mix trim air and conditioned air, then mixing occurs without additional components, but the mixing is not uniform before temperature measurement
Solution Approach 1:
The duct is segmented into multiple sections with guide vanes positioned at specific locations to create staged mixing. The guide vanes divide the airflow into multiple streams that are gradually mixed through rotation, ensuring uniform mixing before the temperature sensor location.
Solution Approach 2:
Guide vanes are introduced as intermediary components between the trim air injection point and the temperature sensor. These vanes act as mediators that induce rotational flow and enhance mixing without requiring complex mechanical mixing devices.
2Measurement precision
If the duct temperature sensor is positioned far from the trim air injection point, then there is more space for mixing, but heat loss through the duct increases leading to low temperature measurements
Solution Approach 1:
Mixing is performed preliminarily within a compact mixing section using guide vanes that induce rapid rotational mixing. This preliminary mixing action ensures uniform temperature distribution before the air reaches the temperature sensor, eliminating the need for long duct sections and reducing heat loss.
Solution Approach 2:
The mixing process transitions from relying on longitudinal duct length to using a transverse rotational dimension. Guide vanes create helical flow patterns that mix air in the radial direction, allowing complete mixing within a shorter axial distance and reducing heat loss opportunities.
3Measurement precision
If additional trim air is injected to compensate for low temperature measurements, then the measured temperature increases, but bleed air usage increases and fuel efficiency decreases
Solution Approach 1:
The system implements feedback control where the temperature sensor provides accurate measurements of the mixed air temperature. This accurate feedback allows the control system to precisely adjust trim air injection to maintain the desired temperature without over-compensation, optimizing fuel efficiency.
Solution Approach 2:
The guide vanes change the flow parameters by inducing rotation and enhancing turbulence. This parameter change accelerates the mixing process, ensuring uniform temperature distribution reaches the sensor quickly, which enables accurate feedback control and prevents excessive trim air injection.
4Adaptability or versatility
If turbulent mixing is relied upon, then no additional mixing components are needed, but the position of trim air injection is limited to long straight portions of ducting
Solution Approach 1:
The duct is divided into a mixing section with guide vanes and a measurement section. This segmentation allows the mixing function to be performed in a dedicated compact section, freeing the injection position from requiring long straight duct portions and enabling installation in various duct configurations.
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 facilitates uniform and complete mixing of airflows, enabling more accurate temperature measurements, reducing heat loss, and optimizing trim air usage, thereby enhancing fuel burn efficiency and minimizing ducting requirements.
Implementation Method 1
The guide vanes are configured to induce rotation of the first and second airflows flowing through the duct
Implementation Method 2
the airflow turbulence in the duct mixes the airflows
Data Source
AI summary
Methods and a device for mixing airflows in an environmental control system are provided. The device includes a duct configured to receive a first airflow and a second airflow, and a plurality of guide vanes disposed within said duct. The guide vanes are configured to induce rotation of the first and second airflows flowing through the duct.