Steerprop CRP Model Tests Confirm Efficiency
Steerprop is now taking one step further, improving the efficiency still by introducing the dual-end CRP propulsor. As a part of the ongoing research and development process of the Steerprop propulsor technology, Steerprop Ltd. recently conducted a series of model tests at Krylov Shipbuilding Research Institute in St. Petersburg, Russia. The Steerprop dual-end contra-rotating propulsor configuration was tested in both the towing tank (open water tests) and in the cavitation tank.
"The test series clearly showed the benefits of the dual-ended configuration and thus also proved the claims for high efficiency of Steerprop CRP. The efficiency of the forward propeller was measured to be close to 0.9!" said Hannu Jukola, hydrodynamist at Steerprop Ltd. This is mainly a result of the interaction between the pulling propeller and the underwater-body, a phenomenon utilized in the dual-end CRP concept. The dual-end CRP concept combines the advantages of a pulling propeller to that of contra-rotating propellers. The efficiency of the pulling propeller is further improved by the use of a bluntly shaped lower body. "The pod geometry is designed to create a pressure wave in front of it, which acts like an additional wake for the forward propeller. The increase in propeller thrust due to this unique interaction between pod and pulling propeller practically cancels the pod drag", explains Hannu Jukola.
During the cavitation tests conducted at the Krylov Institute it was proved that, thanks to the wide non-cavitating operating range, offered by the good inflow quality of the pulling propeller, the propellers of a Steerprop dual-end CRP easily can be designed to be free of cavitation in all normal operating conditions.
The performed model test series was also used to validate the accuracy of the design method newly developed by Steerprop. "The thrust and torque coefficients were found to be within 2 percent of their design values, thus showing an extremely good accuracy of the calculation and design methods" ends Hannu Jukola.