Cavitation threshold pressure of focused ultrasound observed with sonochemiluminescence

2021 ◽  
Author(s):  
Pak-Kon CHOI ◽  
Takumi Akiu ◽  
Shogo Minowa ◽  
Jungsoon KIM ◽  
Kim Moojoon
Keyword(s):  
Focused Ultrasound ◽  
Acoustic Pressure ◽  
Sound Field ◽  
Focal Region ◽  
Pressure Amplitude ◽  
Threshold Pressure ◽  
Schlieren Method ◽  
Background Oriented Schlieren Method ◽  
Cavitation Threshold ◽  
Background Oriented Schlieren

Abstract Spatial distribution of sonochemiluminescence (SCL) from an argon-saturated luminol solution was measured in a focused sound field at 1 MHz in a standing-wave configuration. The SCL distribution was confined to pre-focal region at acoustic powers lower than 0.9 W, and was not located at the focus but at a few mm pre-focal side at a threshold for SCL inception. The threshold pressure amplitude for SCL inception was 3.6 atm at the focus, which value was obtained with a background-oriented schlieren method. The method is based on the broadening of multiple slits due to an optical deflection caused by ultrasound, and the broadening width measured provides an acoustic pressure amplitude. A qualitative image of the focused sound field was also obtained.

scholarly journals Practical Approach for Absolute Density Field Measurement Using Background-Oriented Schlieren

Aerospace ◽  
2018 ◽  
Vol 5 (4) ◽  
pp. 129
Author(s):  
Hidemi Takahashi
Keyword(s):  
Numerical Simulation ◽  
Density Distribution ◽  
Density Field ◽  
Practical Approach ◽  
Two Dimensional ◽  
Schlieren Method ◽  
Absolute Density ◽  
Background Oriented Schlieren Method ◽  
Background Oriented Schlieren ◽  
Aerospike Nozzle

A practical approach for deriving the absolute density field based on the background-oriented schlieren method in a high-speed flowfield was implemented. The flowfield of interest was a two-dimensional compressible flowfield created by two supersonic streams to simulate a linear aerospike nozzle operated under a supersonic in-flight condition. The linear aerospike nozzle had a two-dimensional cell nozzle with a design Mach number of 3.5, followed by a spike nozzle. The external flow simulating the in-flight condition was 2.0. The wall density distribution used as the wall boundary condition for Poisson’s equation to solve the density field was derived by a simplified isentropic assumption based on the measured wall pressure distribution, and its validity was evaluated by comparing with that predicted by numerical simulation. Unknown coefficients in Poisson’s equation were determined by comparing the wall density distribution with that predicted by the model. By comparing the derived density field based on the background-oriented schlieren method to that predicted by the model and numerical simulation, the absolute density field was derived within an error of 10% on the wall distribution. This practical approach using a simplified isentropic assumption based on measured pressure distribution thus provided density distribution with sufficient accuracy.

Observation of Supersonic Jet Using Small Volume High-Pressure Shock Tube

2018 ◽  
Vol 910 ◽  
pp. 143-148
Author(s):  
Ryohei Takemura ◽  
Hiroshi Fukuoka ◽  
Shinichi Enoki ◽  
Shigeto Nakamura ◽  
Kazuki Hiro
Keyword(s):  
Shock Wave ◽  
High Pressure ◽  
Shock Tube ◽  
Small Volume ◽  
Supersonic Jet ◽  
Pressure Chamber ◽  
High Pressure Chamber ◽  
Schlieren Method ◽  
Background Oriented Schlieren Method ◽  
Background Oriented Schlieren

The unsteady supersonic jet and the shock wave injected by the small volume shock tube are experimentally studied in this paper. The experimental was performed by the background oriented schlieren method. The main parameters for the jet are the pressure ratio by the high pressure chamber/ a back pressure 10.9-53.0 and the length of high pressure chamber/diameter ratio 1 and 10. The velocity of the shock wave and supersonic jet were estimated by using the principle of the background oriented schlieren method. The results showed that the influence of the length of the high pressure chamber on the velocity of the jet.

scholarly journals Расчетно-экспериментальное исследование ударно-волнового нагружения оптически прозрачных тел

2019 ◽  
Vol 89 (9) ◽  
pp. 1319
Author(s):  
С.И. Герасимов ◽  
В.А. Кузьмин ◽  
В.А. Кикеев ◽  
Н.А. Трепалов
Keyword(s):  
Numerical Simulation ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Shock Wave Loading ◽  
Wave Loading ◽  
Schlieren Method ◽  
Eulerian Formulation ◽  
Background Oriented Schlieren Method ◽  
Background Oriented Schlieren ◽  
Explicit Solver

The results of computational and experimental studies of shock-wave loading of transparent bodies by two methods are presented: theoretical --- based numerical simulation on a regular three-dimensional grid using an explicit solver in a coherent Lagrangian-Eulerian formulation, experimental - - - using the method of shadow photography and background oriented schlieren method.

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