Efficient Cooling of Automotive Components Using Synthetic Jets

The development of mechanical and electrical components with higher power density is also linked to higher demands on their cooling. Within the close cooperation between CTU and Škoda Auto, a.s., we are looking for new ways to increase the cooling efficiency of these components. The results of the research have shown that selected components can be cooled by so-called synthetic jets and even with higher efficiency than by using standard fans. Furthermore, it is a solution without rotating components with lower production costs and lower failure rates.

The synthetic jet is shown schematically in Fig. 1. The generated vortex field positively influences the boundary layer with an increase in the heat transfer coefficient and improves the approach of cooler air to the surface of the cooled body. For optimal cooling effect, the position of the generator with respect to the cooled surface and suitable parameters of the jet generator are important.

Figure 1: Schematic illustration of the synthesized jet generated by the nozzle. Source:  Silva-Llanca, L., Ortega A.: Vortex dynamics and mechanisms of heat transfer enhancement in synthetic jet impingement, International Journal of Thermal Sciences, 2017.
 

The synthetic jet is generated by a moving diaphragm that compresses the air in the cavity. The air is then accelerated by the nozzle (orifice) (Fig.2)

Figure 2: Illustrative arrangement of the SynJet generator.
 

The results were experimentally verified in the laboratory of the Department of Fluid Dynamics and Thermodynamics, Faculty of Mechanical Engineering. A special stand for the measurement of the heat transfer coefficient was developer (Fig. 3). The stand allows the use of the Syn Jet generator in different configurations and with different parameters.

Figure 3: Experimental setup for testing the SynJet generator parameters and its effect on the heat transfer coefficient.
 

An example of one of the design variations of the SynJet generator and cooled component arrangement is shown in Fig. 4. Here it is a two-acting arrangement using both strokes of the generator diaphragm.

Figure 4: SynJet generator located near the cooled component.
 

The achieved values of the heat transfer coefficient were up to 80% higher than those achieved with standard fans. Currently, the work is focused on testing the developed generators directly in real conditions. The results will be known in a very short time.

In 2024, a thesis on this topic was written by Antonín Zeman entitled "Utilization of synthetic jet for the intensification of the heat transfer coefficient". The thesis was successfully defended in 2025.

In collaboration with:

Contact:

doc. Ing. Michal Schmirler, Ph.D.

Department of Fluid Dynamics and Thermodynamics FME CTU in Prague

E-mail: michal.schmirler@fs.cvut.cz

Phone: +420 604 735 257