Aircraft Engine Particle Emission Measurement System
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Solution Overview
Problem
Current methods for measuring particle emissions from aircraft engines suffer from high particle losses due to the need for long lines, which require balancing inner diameter and flow rate, and the use of 'in-line' pumps leads to uncontrollable and enormous losses, especially when measuring pollutants and particles simultaneously.
Innovation Solution
A system that includes a first flow divider to separate the exhaust gas flow into particle and blow-off lines, with a pressure sensor to maintain a predetermined overpressure, and a second flow splitter to achieve a constant flow rate, along with temperature-controlled components to minimize losses, utilizing an 'ejector dilutor' for dilution and a cyclone for particle separation, and a mass flow controller to ensure robust measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If long lines are used to connect the engine to measurement instruments due to spatial separation requirements, then the engine can be tested with separated instrumentation, but particle losses in the lines become very high
Solution Approach 1:
A heated transport line acts as an intermediary component between the engine exhaust and measurement instruments. The line is actively heated to maintain particles in a suspended state and prevent condensation, thereby reducing particle losses while allowing the necessary spatial separation for engine testing.
Solution Approach 2:
The temperature parameter of the transport line is changed and maintained at elevated levels (heated to 60°C or higher). This parameter change prevents particle condensation and minimizes losses along the long connection lines, enabling spatial separation without sacrificing measurement accuracy.
2Speed
If an 'in-line' pump is used to maintain flow rate in the particle measurement line, then flow rate can be controlled, but particle losses become enormous and uncontrollable
Solution Approach 1:
The pump is extracted from the direct particle measurement line and relocated to the exhaust gas sampling line. This separation removes the source of uncontrollable particle losses from the particle measurement path while still enabling flow rate control in the overall system through the pump's operation on the exhaust gas stream.
Solution Approach 2:
The flow control function is segmented into separate zones: the pump operates on the exhaust gas line to establish overall flow, while the particle measurement line receives a portion of this controlled flow through a flow splitter. This segmentation allows flow rate management without exposing particles to the pump's harmful effects.
3Adaptability or versatility
If multiple instruments are attached to measure particle mass, number and size distribution simultaneously, then comprehensive particle characterization is achieved, but maintaining constant flow rate becomes more difficult
Solution Approach 1:
The particle measurement flow is segmented into multiple parallel branches using a flow splitter, with each branch leading to a different measurement instrument (mass, number, size distribution). This segmentation allows multiple measurements simultaneously while the main line upstream maintains constant flow rate, which is then distributed proportionally to each instrument.
Solution Approach 2:
The main particle transport line serves multiple functions: it maintains constant flow rate, distributes samples to multiple instruments, and provides a common reference point for all measurements. This multi-functionality enables comprehensive particle characterization while preserving flow rate stability through centralized control.
4Loss of substance
If the inner diameter of the pipe is increased to reduce particle losses, then particle losses decrease, but the pressure drop becomes too large for the instruments
Solution Approach 1:
The temperature parameter of the transport line is increased (heated to 60°C or higher), which changes the physical properties of the exhaust gas and particles. This parameter change reduces particle condensation and allows for optimized pipe dimensions that minimize both particle losses and pressure drop, as the heated gas maintains better flow characteristics.
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 achieves simultaneous measurement of particle mass, number, and size distribution with minimized particle losses, maintaining a constant flow rate and pressure drop, even at high engine power, and allows for the introduction of particulate matter certification for aircraft engines.
Implementation Method 1
a device with a first flow divider, the inlet of which is connected to a probe for sampling exhaust gas from the aircraft engine and which divides the exhaust gas flow into a particle line and a line connected to a blow-off valve
Implementation Method 2
a pressure sensor is provided upstream of the inlet of the first flow divider, by means of which a predetermined overpressure is set upstream of the first flow divider
Implementation Method 3
the particle line from the first flow divider being connected to the inlet of a first dilution stage, in which the exhaust gas is diluted in a specific ratio
Implementation Method 4
two appropriately placed pressure sensors to monitor a constant pressure drop in a transport line that is temperature-controlled at 60°C
Implementation Method 5
an output of the second flow divider is connected to an instrument for particle measurement and another output of the second flow divider to a Pump
Implementation Method 6
Pump is connected to set a predetermined flow rate through the particle line
Data Source
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AI summary
So as to verify compliance with limit values for harmful substances, large engines today must be tested in accordance with the regulations of the International Civil Aviation Organization (ICAO). Presently neither a standardized measuring method nor a standard exists with respect to particulate emissions (ultrafine particles). The invention relates to the creation of a standardized transport system having the lowest possible loss for measuring ultrafine particles of aircraft engines, which can be operated simultaneously with the harmful substance measurement of aircraft engines stipulated until now. Appropriate instruments for measuring the particle count, mass and size distribution can be connected to this transport system.