Aeroacoustics: the Whispering Wind
Noise design and control are important research subjects at Bosch. Many products conduct or are exposed to airflows. The resulting noise can be either pleasant or disturbing. Aeroacoustics researchers at Bosch are investigating these phenomena with state-of-the-art methods.
Much in the way an organ builder uses enthusiasm and a fine ear to tune the stops of an organ, Bosch scientists and development engineers optimize individual flow-conducting components in automobiles, gas-fired condensing boilers and electric power tools. But while the organ builder strives to attain harmony and melodiousness of individual sounds, acoustics researchers at Bosch work with purely technical noise – phenomena in an engineered soundscape that they have to shape to satisfy the customer. Aeroacoustics research is a challenging discipline, in which even the smallest causes can generate big effects in terms of noise. From a physical viewpoint, the energy of sound is several orders of magnitude lower than the kinetic or calorimetric energy in the airflow that generates them. Simply put, airflows can generate undesirable noise with relative ease. Bosch scientists are creating solutions to this problem.
They use their understanding of the fundamental physical phenomena of aeroacoustics to make minute changes in the design of components that conduct airflow. Such purposeful changes can substantially improve the resulting overall sound. This research requires both experimental work and CAE tools (CAE = Computer Aided Engineering). Practical knowledge derived from the experiments is used to design, validate and perfect reliable numerical simulation tools. The object is not only to observe patterns of sound generation and propagation, but even to predict them. In the future, the resulting software tools will in large measure replace complex experiments, especially in determining component geometry. So which repertoire do these Bosch aeroacoustics experts have to master? They deal with all kinds of flow-conducting nozzles and valves, the soft operation of residential heating systems, the quiet tone of an angle-grinder running at idle, the reassuring sound of air flowing over the windshield wipers and much more.
They use their understanding of the fundamental physical phenomena of aeroacoustics to make minute changes in the design of components that conduct airflow. Such purposeful changes can substantially improve the resulting overall sound. This research requires both experimental work and CAE tools (CAE = Computer Aided Engineering). Practical knowledge derived from the experiments is used to design, validate and perfect reliable numerical simulation tools. The object is not only to observe patterns of sound generation and propagation, but even to predict them. In the future, the resulting software tools will in large measure replace complex experiments, especially in determining component geometry. So which repertoire do these Bosch aeroacoustics experts have to master? They deal with all kinds of flow-conducting nozzles and valves, the soft operation of residential heating systems, the quiet tone of an angle-grinder running at idle, the reassuring sound of air flowing over the windshield wipers and much more.
Abstract art? Not quite. Sound waves generated by airflow striking a surface, such as a windshield, are propagated from the left margin of the illustration.
