This study presents a CFD comparison of a piccolo tube inlet anti-icing system with benchmark flight test data and a shielded swirl design.
Aircraft engine inlets must prevent ice accretion that could cause damage or inhibit safe operation. A common way to meet this requirement is to heat the inlet with hot air distributed with a piccolo tube or a swirl anti-icing system. Piccolo tube systems generally use less engine bleed air but are more complex and heavier than swirl systems.
The CFD model for this study includes all the inlet key characteristics such as piccolo tube holes, material properties, and thickness. The model is evaluated in a two-step process. Water collection rates for flight in icing conditions are calculated. These results are then mapped onto a conjugate heat transfer film runback model. The CFD results include surface temperatures and the amount of liquid film runback that flows off the heated surface.
Benchmark test data is presented illustrating good inlet surface temperature agreement with the piccolo tube CFD model for flight in both dry air and icing conditions.
This CFD modeling approach is also applied to a unique shielded swirl anti-icing system. The results of this study confirm that a shielded swirl anti-icing system can be designed to provide the same level of anti-icing protection that is achieved with a piccolo tube configuration without overheating the inlet or requiring more engine bleed flow.