Fraunhofer Institute for Process Engineering and Packaging IVVLearning from nature, minimal use of resources, efficient cleaning
Key challenges of new cleaning processes are improved cleaning, reduced use of resources, and shorter cleaning times. Examples include the reduction of cycle times for industrial component and electronics cleaning as well as increased availability of processing machinery in the food industry.
The specific objective is to develop spray cleaning processes using fluid jets, namely the most important cleaning method used in many industries, in a more efficient way with respect to their time, water, chemical, and energy requirements.
Archerfish generate high-impulse water jets for hunting prey
A promising approach is based on the fascinating hunting strategy of the archerfish and this is being investigated in the recently started BionicJet project. The archerfish directs a jet of water from its mouth at insects on leaves above the water surface, causing the prey to fall into the water. In order to create a jet of water with sufficiently high impulse at distances of up to 0.6 m, a water blob is formed at the impact point. This hits the insect with high force and throws it into the water.
The underlying mechanism is based on water volume concentration, namely the mouth of the fish creating a jet of water that travels faster at the rear than at the front. This speed differential causes the jet of water to become a blob. The archerfish adapts this process to the distance to its prey so that the blob of water is fully formed when it reaches the insect.
The principle of volume concentration over a specific time or jet length, causing a shorter but more intense impact on the target object, is termed the hammer jet effect.
Hammer jet effect enhances mechanical cleaning performance
The use of the hammer jet effect for spray cleaning has enormous potential for improving the cleaning performance and consequently reducing the cleaning time and cleaning fluid usage by 50-80%. Feasibility tests showed there was at least a 7.5 fold higher impact force using the novel hammer jet process compared to continuous fluid jets and a 10 fold greater cleaned area.
The research project is validating the improved mechanical cleaning effect and a prototype for generating hammer-modulated spray jets is being developed. The project is focusing on the use of the hammer jet principle in combination with cleaning robots. These are used in a wide range of industries for cleaning, for example, industrial components and food processing plants.