Discrepancies in The Burril Diagram Method / Discrepâncias no Método do Diagrama de Burril

• Autor(a) principal: Bondan, Thiago Gilberto
• Data de Publicação: 2021
• Outros Autores: Cunha, Marcos Paulo Martinez Souza, Amado, Flavio Peres
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Revista Veras
• Texto Completo: https://ojs.brazilianjournals.com.br/ojs/index.php/BRJD/article/view/29533
• topic: Cavitation; Burril Diagram; Marine Propellers

The method of analysis of cavitation in marine propellers that takes into account the Burril Diagram is one of the most used by designers worldwide. The literature has reported this technique as reliable and quite useful in the design of fixed pitch conventional propellers. However, an accurate execution of the method shows that the calculations for cavitation at 2.5% on the back of the blades can indicate this percentage as having happened after cavitation at 10% or even after cavitation at 20%, which makes it physically impossible. In addition, there may be negative values of expanded area, which results in a wrong indication of cavitation. In this sense, cavitation prediction calculations for five diameters were performed: a small commercial component of 0.25 m, a large of 10 m, belonging to a large oil vessel and three intermediaries, for comparison of results and reinforcement of conclusions. Within the examples of propellers tested, it was possible to conclude that the Burril Diagram works well for constructive blade angles between 60 and 67 degrees, paired with a 45-degree angle, with an inclination to the left. But most of the time, it provides false indication of cavitation for angles less than 60 degrees and greater than 67 degrees. It was also possible to verify that the larger the propeller diameter, the smaller the error range in the 2.5% cavitation indication. In view of these facts, the Burril Diagram method does not become invalid, but it is concluded that it must be used with due care, within the indicated safety range.