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Aerospace 2018, 5(4), 129; https://doi.org/10.3390/aerospace5040129

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

Japan Aerospace Exploration Agency, Kakuda, Miyagi 981-1525, Japan
Received: 21 November 2018 / Revised: 10 December 2018 / Accepted: 14 December 2018 / Published: 17 December 2018
(This article belongs to the Special Issue Design and Analysis of Wind-Tunnel Models and Fluidic Measurements)
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Abstract

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. View Full-Text
Keywords: background-oriented schlieren; flow visualization; supersonic flowfields; post-processing background-oriented schlieren; flow visualization; supersonic flowfields; post-processing
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Takahashi, H. Practical Approach for Absolute Density Field Measurement Using Background-Oriented Schlieren. Aerospace 2018, 5, 129.

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