In-situ characterisation of structure borne noise from a building mounted wind turbine

Building mounted micro wind turbines (BMWTs) could potentially provide a useful contribution to renewable energy production but a means of predicting structure-borne sound and vibration is required. A particular difficulty is that BMWTs can only be operated when properly installed, therefore any source characterization measurements must be conducted in situ. Methods such as inverse force synthesis are possible but would only give a description of the source activity for a specific case. This paper describes the application of a new source characterization procedure whereby a source (BMWT) is characterized in terms of blocked forces measured in-situ. The main advantages of the approach are that (1) all required measurements can be performed in-situ and (2) the blocked forces obtained are an independent property of the source and can therefore be transferred to predict levels in different installations. Examples of measurements on idealized structures and on a mock-up wind turbine installation are given. The validity of the approach is confirmed by comparing measured and predicted velocity at different points on the same receiver structure and in a different receiver structure.