The value of compressor washes in aviation
05.24.19
When it comes to jet engines, the more efficient the better. An efficient engine is safer, works better, and requires less fuel to run.
That’s all pretty straightforward, but how can you help maximise the efficiency of your jet engine? It comes down to effective compressor cleaning.
Contaminants and where they come from
Although you can rarely see it, the air around us is filled with contaminants.
That is particularly true as we get closer to the ground.
Mixed in with harmless gases you’ll find things such as:
- Fine dirt
- Oil vapours
- Soot
- Exhaust fumes
- Salt
…and these contaminants enter the compressor with the air supply.
The air in the jet engine compressor is under extremely high pressure and temperature, causing an accelerated build-up of contaminants on the compressor blades.
Thermal efficiency
In a gas turbine such as that in a jet engine, thermal efficiency is a key component of performance. The factors affecting thermal efficiency in this instance include:
- Turbine inlet temperature
- Compressor inlet temperature
- Burner efficiency
- Compression ratio
- The efficiency of the compressor and turbine
That last factor is the one we’re really interested in maximising as much as possible.
The problem with the build-up of contaminants is that they interfere with the air flow, with a knock-on effect on the efficiency of the whole system.
A further potential problem is that some contaminants, particularly salts, can corrode certain components in the jet engine.
This leads to even greater disrupted airflow and the premature degradation of parts. It can even ultimately result in engine failure.
The bottom line is that an inefficient system is best dealt with as quickly and thoroughly as possible.
What is compressor washing?
is exactly what it sounds like: cleansing the jet engine compressor of contaminants.
This is done by using hot water or hot water mixed with a specialised detergent in order to dissolve, dislodge and remove contaminants. It’s carried out in three main steps:
- Chemical wash. Using specialised equipment such as the Ro-Jet system, detergent is injected into the system while the compressor turns.
- Water rinse. Once the detergent has broken down the contaminants it is time to flush the compressor with water to remove all residues including the cleaning chemicals.
- Engine run. Once the cleaning has been completed, the engine can be quickly and easily dried by briefly dry-motoring it or by carrying out a fired dryout run.
Special considerations for compressor washing
Specialised equipment
To ensure a safe and effective clean, it’s important to use the right equipment. The (Ro-Jet – is this the correct naming strategy?
I refer to the system as the “Rochem Jet Wash – RJW”) wash system has been designed specifically for the job and has a proven track record of fantastic results time and time again.
Specialised products
If using a , it’s essential to use one designed exactly for the purpose.
Water quality
It’s highly recommended that de-mineralised water (Note: demin water is more commonly available) is used for all cleaning and rinsing of the compressor.
That is because impure water can carry contaminants that may become deposited on the compressor… exactly what you’re trying to avoid!
The advantages of regular cleaning
Having a regular wash schedule stops contaminants from building up to the level at which they become a problem.
The cleaner the compressor, the more efficiently it will run. Like with any cleaning, regularly removing contaminants means they are also easier to remove.
How often you conduct a clean is detailed in the AMM and is based on cycles or when the EGTM needs recovery.
There are different variables to consider such as air quality and the kind of trips the aircraft carries out.
If the aircraft is used for regular low altitude flights in the more highly polluted air, it may be wise to clean the compressor more often than on a craft whose journeys are predominantly at high altitude.
Weigh up the cost of cleaning against the cost associated with lost efficiency to help determine how often to carry out compressor washing.
Find out more
To find out more about how regular compressor cleaning with the Ro-Jet system could work for you, contact us today.
We’ll be happy to talk about your specific requirements and recommend a system for your needs.
Post written by Martin Howarth
An extensive knowledge of mechanical and electrical engineering together with hands on experience with gas turbines provides a bedrock for his work at Rochem.
