Investigation of Liquid Film Cooling in Small Rocket Engines

The ESA GSTP Project on Investigation of Liquid Film Cooling in Small Rocket Engines has been close-out, developing an advanced and accurate not-intrusive LIF approach to detect the temperature of the micro-metric liquid layer. The Belgian-German working group (VKI / DLR) has tackled some of the challenges related to the physical understanding and modeling of the phenomena by means of both numerical and experimental activities.

The VKI has been leading the development of an advanced optical method to detect the temperature of a very thin liquid film of ethanol. The M11 DLR facility was used to reproduce the shear-driven micrometric film inside a measurement section designed and manufactured by Ariane Group.

Quartz windows along the channel allowed the detection of the fluid temperature by means of the Lases Induced Fluoresce technique (LIF). LIF is a non-intrusive (i.e. optically-based) measurement technique: an unstable energy state of a specific dye dissolved in the test fluid is created, by exiting it at a certain energy wavelength. The solution consequently emits a fluorescent light signal, whose intensity can be related to the liquid temperature. This method was specifically tailored by the VKI experts to meet the preset scope ambitious requirements, achieving a very satisfactory accuracy in the measurements.

The experimental data obtained thanks to the joint efforts of VKI and DLR contribute to the sound understanding of the liquid cooling process and represent a valid benchmark test case for numerical models developments and validations.

More information: 
S. Soller, al., EXPERIMENTAL AND NUMERICAL INVESTIGATION OF LIQUID FILM COOLING IN SMALL ROCKET ENGINES, 7^TH EUROPEAN CONFERENCE FOR AEROSPACE SCIENCES (EUCASS 2019), OI: 10.13009/EUCASS2019-150