Introduction

Background

Objectives


Test facility

Diagnostic techniques


Cross-flow influence

Overall boiling curves

Intermittent cooling efficiency

Heat transfer correlations






 

 
Advances in Intermittent Spray Impact Research

micro nano engineering
   

  Test facilities

… for studies on spray impingement interacting or not with a cross-flow.
The spray issues from a commercial pintle-type injector used in PFI gasoline engines. The injector is placed vertically faced downwards at the top of the working section of a wind tunnel (270 mm long (L), 150 mm wide – see figure below) and sprays through a cross stream of air perpendicularly onto the bottom surface, which is located at 50 mm (H). The sidewalls of the working section are made of glass to provide optical access to the flow and the target surface is made of aluminium with a mean roughness of 2.5µm. The fluid used is commercial gasoline.


… for overall heat transfer studies.
An aluminium plate 12 mm thick is heated by an electric resistance isolated from below. Three NANMAC fast-response (~10 µs) are assembled in L-shape and connected with a 300 gain signal amplifier which transmits the voltage information to a PC computer through a BNC2110 from National Instruments. This is not available for temperature measurements with an imposed heat flux.


… for local spray/wall interaction and heat transfer studies.
A flat aluminium disc with a 10 mm radius is heated by an electric resistance and a copper plate uniformly distributing heat to the disc. Three “Medtherm” eroding-K-type thermocouples were assembled in the disc and spaced by 4 mm with the first thermocouple located at the disc centre as depicted in the figure below. Thermocouples signals are sampled with a NI6024E National Instruments DAQ board plus a BNC2120, and the electrical signal is amplified with a gain of 300 before processing. This rig allows the surface temperature measurement with an imposed heat flux.