AdaPtation of gRec to Intense Turbulence Fluctuations experiements EuHIT Funded Project

Team

Vladislav Benda
Cern, Geneva, Switzerland
Youry Borisenkov
Tel Aviv University, Tel Aviv, Israel
Benoit Michel Chabaud
CNRS - Institut Néel, Grenoble, France
Resagk Christian
Ilmenau University of Technology, Ilmenau, Germany
Robert Kaiser
Technische Universität Ilmenau, Ilmenau, Germany
Olivier Pirotte
Cern, Geneva, Switzerland
Eléonore Rusaouën
Institut Néel, Grenoble, France
Julien Salort
Ecole Normale Superieure de Lyon, Lyon, France

Overview

Research Infrastructure
CERN Cryogenic Turbulence Facility, Switzerland
Facilities used
CERN Cryogenic Turbulence Facility (GReC)
Project leader
Philippe Roche
CNRS, Grenoble, France

Abstract

CERN’s turbulence facility provides a cryogenic helium jet developing in a 3-m-high cylindrical enclosure. This experiment offers amazing perspectives for the study of ultra high Reynolds number (Re-lambda up to 6000), thanks to its unusually large dimension for a cryogenic flow. In this flow, a cutting-edge cryogenic hot-wire could resolve 4.5 decades of turbulent scales, from the 40-cm eddies down to a typical 10-micron-resolution of anemometers. But such difficult and demanding measurements are only worthwhile in a flow tailored to match at best the academic reference for axisymetric steady jet turbulence. Before attempting this high-dynamics measurement with a network of hot-wires, the GReC facility should be specially adapted for this specific objective, in particular in terms of flow stability, probe mounting system and absence of helium droplets in the helium gas.

The Euhit Tritium project is taking place in 2015 : one week in July and another planned in November. This previous project focuses on the low velocity regime (most data acquired below 70 g/s, compared to the 250 g/s maximum flow rate of the facility). A panoply of rough probes is used to characterize the flow : thermometers, pressure probes, macroscopic Pitot tubes, accelerometers and mass-flow rate. Ways to avoid droplets and optimise the flow stability were identified in July and will be validated in November. Preliminary tests of hot-wires and micro-machined thermometers are performed.

The main motivation of this new 1+1 weeks proposal for 2016 is to extend the previous work to high flow rate regime, up to 250 g/s, and extend the characterization of flow properties. The 3 institutions who participated in the 2015 Tritium projet (CNRS-Grenoble, ENS-Lyon, Ilmenau University) will be completed by a new one : Tel Aviv university.