Helicopter Engines – Understanding the Constant Threats and Analyzing their Effects with AxSTREAM

Helicopter landing on a desert
Figure 1: Helicopter landing on a desert – burnout threat

The helicopter is a sophisticated, versatile and reliable aircraft of extraordinary capabilities. Its contribution to civil and military operations due to its high versatility is significant and is the reason for further research on the enhancement of its performance. The complexity of helicopter operations does not allow  priority to be given for any of its components. However, the main engine is key for a successful flight. In case of engine failure, the helicopter can still land safely if it enters autorotation, but this is dictated by particular flight conditions. This article will focus on the possible threats that can cause engine failure or deteriorate its performance.

When a helicopter is operating at a desert or above coasts, the dust and the sand can challenge the performance of the engine by causing erosion of the rotating components, especially the compressor blades. Moreover, the cooling passages of the turbine blade can be blocked and the dust can be accumulated in the inner shaft causing imbalance and unwanted vibration. The most common threat of this kind is the brownout which is caused by the helicopter rotorwash as it kicks up a cloud of dust during landing.

Helicopter covered with ice
Figure 2: Helicopter covered with ice

In addition to dust, ice can lead to catastrophic results when it comes to engine operation. The ice is usually formed by water droplets that reach the rotorcraft surface and freeze. Solid ice contamination can form in the engine inlet duct due to the lower temperature created by the inlet depression. If the ice is ingested into the air system, it will act as a solid object causing serious damage to the engine compressor. On top of that, accumulation of ice at the air intake may cause air starvation to the engine.

Helicopters can also face threat from salt during sea operations. Formation of salt deposits on engine components can lead to component erosion, imbalances and power loss as a consequence. The final phenomenon that will be discussed is the ingestion of hot gases which is caused when the exhaust gases are re-ingested into the inlet because of flight conditions and wind direction. This may lead to a significant increase of inlet temperature and further to a reduction of engine power. Furthermore, potential temperature and flow distortion at the inlet of the compressor can lead to compressor stall and engine failure.

helicopter operating above sea water - salt threat
Figure 3: Helicopter operating above sea water – salt threat.

In order to analyze the performance of the helicopter engine when facing the above threats, engineers are in need of a powerful tool that will allow them to study all aspects of turbomachinery. From the analysis of rotating components experiencing erosion and off-performance effects to rotordynamics and cooling systems, AxSTREAM is the platform that can help engineers get a deep understanding of the machine.

Register now for the upcoming AxSTREAM training on centrifugal compressors (taking place September 18-22) that will cover fundamentals related to the effects described above as well as practical exercise with the AxSTREAM platform, and get the chance to use the tool for free to design and analyze your own machines.

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