Particle tracer response across shocks measured by PIV

By D. Ragni, F. Schrijer, B. W. van Oudheusden, Fulvio Scarano. 2011

246 citations recorded by the source corpus.

The experimental approach used for the evaluation of the particle response time across a stationary shock wave is assessed by means of PIV measurements. The study focuses on the experimental requirements for a reliable and unbiased measurement of the particle response time τp and length ξp based on a single-exponent decaying law. A numerical simulation of the particle response experiment returns the parameters governing the measurement: namely the normalized spatial and temporal resolution, shock strength, and digital resolution. Representing the velocity decay in logarithmic coordinates it is shown that measurements performed with laser pulse separation time up to τp and interrogation window up to ξp still yield unbiased results for the particle response. A set of experiments on the particle response across a planar oblique shock wave was conducted to verify the results from the numerical assessment. Liquid droplets of DEHS and solid tracer particles of silicon and titanium dioxide with different primary crystal size are compared. The resulting temporal response ranges from 2 to 3 μs, corresponding to values commonly reported in literature, to almost 0.3 μs when particles are properly dehydrated and a filter is applied before injection into the wind tunnel. It is the first experimental evidence of particle tracers with a measured response time lower than 0.4 μs. The same procedure is applied to attempt the measurement of individual particle tracers by particle tracking velocimetry to estimate the spread in the distribution of tracer time response. The latter analysis is limited by the particle image tracking precision error, which biases the results introducing a wider broadening of the particle velocity distribution.

Subfields: Computational Mechanics, Environmental Engineering, Ocean Engineering

View Paper: https://www.semanticscholar.org/paper/03954dbdf46209d724ad0a49949be854e6242fbe

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Computational Mechanics

In Environmental Engineering

In Ocean Engineering

Citations in the corpus

On the use of helium-filled soap bubbles for large-scale tomographic PIV in wind tunnel experiments (2015, methodology): “The reference velocity field is measured using 1 µm size liquid dr plets from a glycerine water solution, which a e known to follow the flow fluctuat ons within a short response time (2 µs according to Ragni et al. 2011).”
Coherent structure and sound production in the helical mode of a screeching axisymmetric jet (2014, result): “Nonetheless, this relaxation time is comparable with the best performance of tracer particles in the current literature (Ragni et al. 2011).”