In an ideal world, the inlet of gas turbines, compressors, jet engines and other rotating equipment would experience uniform flow.
This means that the inlet of the equipment would be unobstructed and the fluid entering the inlet would not be flowing with a severe entry angle or other unfavorable conditions. There are many different types of inlet distortions but in simplified terms, inlet distortion is non-uniform flow upstream of the inlet of rotating equipment and non-uniform flow in the intake duct.
Inlet distortion: What is it, and why should you care?
Uniform inlet flow versus non-uniform inlet flow
Most equipment, especially jet engines, can handle a minimal level of inlet distortion, especially if it was taken into consideration during the design of the equipment. In severe cases, this non-uniform pressure distribution around the inlet face could affect equipment performance and even lead to equipment failure and shortened equipment life. The figures below demonstrate inlet distortion in gas turbine engine inlets.
Common causes of inlet distortion include:
- Short intake duct preventing development of uniform flow
- Obstructed intake ducts
- Jet engines sitting on the tarmac, causing distortion due to pulling in air while being close to the ground
- Fighter jets executing sharp turns or sudden maneuvers, causing suddenly changing inlet conditions
- High angle of attack airplane take-offs
Why should you care about inlet distortion?
Inlet distortion has the potential to severely disrupt operation, cost and equipment life. In jet engines, severe inlet distortion can degrade engine performance, such as affecting engine thrust and engine specific fuel consumption. It can also reduce the engine safe operating range by increasing the risk of stall or compressor surge. In some rare cases, the inlet distortion can cause a significant change to the unsteady aerodynamic profile of pressure loading on fan or compressor airfoils, leading to a significant increase in vibratory stress. This increased vibratory stress can lead to shortened equipment life and, in some cases, rapid equipment failure.
With years of experience analyzing process and performance data, analyzing fluid flow using computational fluid dynamics (CFD) and designing solutions for clients, KnightHawk Engineering is your one-stop shop for tackling these types of problems.
Inlet distortion: What is it, and why should you care?
Normal inlet airflow versus distorted inlet airflow
KnightHawk Engineering can analyze and model inlet conditions using CFD to determine the severity of inlet distortion and to gain full understanding of what is causing it. This allows for the development of a targeted, custom solution that will tackle the root cause of the issue. KnightHawk has first- hand experience designing and implementing flow distributors and flow correction solutions that can assist in solving inlet distortion issues in ducted equipment.
KnightHawk Engineering can also help with testing for inlet distortion. With a readily available suite of pressure testing instrumentation and mobile data acquisition equipment, KnightHawk can go anywhere in the world to assist with inlet pressure testing. It also has the capability to design and develop inlet distortion testing screens, which are meshed or gridded screens that can be designed to induce specific inlet distortion conditions. These screens can be placed at the inlet of a gas turbine engine, fan, compressor or other rotating equipment to test the effect of inlet distortion on performance.
For more information, visit knighthawk.com or call (281) 282-9200.
