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Fluidics

CFD Animation der Strömung im fluidischen Oszillator (click to play)
 

The name ‘fluidics’ is a combination of the words ‘fluid’ and ‘logic’. It describes flow devices which were designed to enable analog or digital processes. These devices are commonly called ‘fluidics’ and do not include any moving parts. They were developed in the 1960ies in the Harry Diamond Laboratories to enable complex switching operations (e.g., guidance system for rockets) for which the infant electronics at the time were not robust enough. Therefore, fluidic amplifiers, triodes, diodes, switches, and various other configurations were developed to design complex control systems. With substantial advances in electronics, fluidic devices were rendered impractical and were almost forgotten.

Beside the application as logical switches, fluidic devices also found their use in other areas. Especially fluidic oscillators were utilized for various purposes. These devices emit an oscillating jet at its exit. Therefore, they are especially suitable to distribute fluids and gases. For example, these devices are used as spray nozzles to distribute windshield washer fluid in automobiles.

Today, fluidic devices are mainly used as nozzles to distribute water or air. However, these devices continue to be researched. For example, areas such as active flow control, mixing enhancement, and combustion control are currently the main focus of ongoing research. At the research group for experimental fluid mechanics these research areas are currently being pursued. Furthermore, fluidic devices are investigated for actuation purposes.

Fluidic Devices for Mixing Enhancement

A high quality of mixing between fluids is important for the production
time and quality of various industrial processes. Combustion engines
also require a sufficiently high mixing quality between fuel and air. It
is crucial for an efficient and clean combustion process which directly
effects the emission of pollutants. The mixing quality is commonly
provided by devices that either require a very high supply pressure to
provide acceptable mixing quality or involve moving parts which are
often accompanied by a short life span and costly maintenance. The
application of fluidic oscillators presents an alternative to ensure a
desired mixing quality. Recent studies have shown that this technology
is capable to significantly improve the mixing quality (REF). These
passive devices are characterized by robustness in any environment, no
maintenance, versatility for various applications, and almost unlimited
scalability to any small or large size. In the research group, these
devices are being investigated numerically and experimentally with
regards to their properties for mixing enhancement.

Fluidic Devices for Active Flow Control

Active flow control is of interest in various areas of aviation to reduce fuel consumption and noise levels, to increase lift, and to improve the maneuverability of aircraft. For these purposes fluidic oscillators have been successfully applied in recent years. In order to advance the research and development of fluidic devices, various designs are currently being investigated for their general and application-specific properties to explore the influence of relevant geometric parameters.

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