Rainbow schlieren measurements in underexpanded jets from square supersonic micro nozzles

Maeda, Hiroaki; Fukuda, Hikaru; Nakao, Shinichiro; Miyazato, Yoshiaki; Ishino, Yuji

doi:10.1051/epjconf/201818002058

Cited by 4 publications

(6 citation statements)

References 8 publications

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“…Kolhe & Agrawal (2009) applied for the first time the rainbow schlieren deflectometry to a shock-containing jet issued from a micro cylindrical nozzle with an inner diameter of 500 µm at the nozzle exit. Maeda et al (2018) measured the density in a slightly underexpanded free jet issued from a micro nozzle with a design Mach number of 1.5 and a square shape of 1 mm × 1 mm at the nozzle exit plane. In their approach, a rainbow schlieren system combined with the computed tomography was utilized to reconstruct the jet three-dimensional density fields.…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional reconstruction of a microjet with a Mach disk by Mach–Zehnder interferometers

et al. 2020

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Section: Introductionmentioning

confidence: 99%

Three-dimensional reconstruction of a microjet with a Mach disk by Mach–Zehnder interferometers

et al. 2020

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“…In Figure 27, an example of color Schlieren applied to a supersonic nozzle, for an air-to-air jet, is shown. In [45], rainbow Schlieren deflectometry was used with computed tomography to measure the three-dimensional density fields of free jets containing shock from micro nozzles. The layout of the laboratory set-up is shown in Figure 28, wherein the <xz> plane In [45], rainbow Schlieren deflectometry was used with computed tomography to measure the three-dimensional density fields of free jets containing shock from micro nozzles.…”

Section: Schlieren Techniquementioning

confidence: 99%

“…In [45], rainbow Schlieren deflectometry was used with computed tomography to measure the three-dimensional density fields of free jets containing shock from micro nozzles. The layout of the laboratory set-up is shown in Figure 28, wherein the <xz> plane In [45], rainbow Schlieren deflectometry was used with computed tomography to measure the three-dimensional density fields of free jets containing shock from micro nozzles. The layout of the laboratory set-up is shown in Figure 28, wherein the <xz> plane feeding system of the nozzle is well explained: an electrovalve regulates the flow going inside a plenum chamber, where the dynamical pressure effect is dumped.…”

Section: Schlieren Techniquementioning

confidence: 99%

“…This technique requires the calibration of the system, moving the rainbow filter in the Schlieren cut of the plane and reporting the hue as a function of the coordinate of the filter (Figure 30). A 3D analysis [45] is performed at a different constant z coordinate, rotating the nozzle around the z axis, which was required because the nozzle was not axisymmetric. The images acquired with the rainbow Schlieren are less detailed (in terms of edges) than the other Schlieren techniques (Figure 31), and the key role is played by the postprocessing with the convolution-back projection algorithm (CBP).…”

Section: Schlieren Techniquementioning

confidence: 99%

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Optical Diagnostics for Solid Rocket Plumes Characterization: A Review

et al. 2022

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In recent decades, solid fuel combustion propulsion of spacecraft has become one of the most popular choices for rocket propulsion systems. The reasons for this success are a wide range of applications, lower production costs, simplicity, and safety. The rocket’s plumes leave the nozzle at high temperatures; hence, the knowledge of produced infrared (IR) emissions is a crucial aspect during the design and tests of the rocket motors. Furthermore, rocket plume composition is given by N2, H2, H2O, CO and CO2, while solid rocket motors (SRM) additionally inject some solid particles, given by metal fuel additives in the propellant grain, i.e., aluminum oxide (Al2O3) particles. The main issue is the detection of the particles remaining in the atmosphere due to the exhaust gas of the solid rocket propulsion system that could have effects on ozone depletion. The experimental characterization of SRM plumes in the presence of alumina particles can be conducted using different optical techniques. The present study aims to review the most promising ones with a description of the optics system and their potential applications for SRM plume measurements. The most common measurement techniques are infrared spectroscopy imaging, IR imaging. UV–VIS measurements, shadowgraph, and Schlieren optical methods. The choice of these techniques among many others is due to the ability to study the plume without influencing the physical conditions existing in and around the study object. This paper presents technical results concerning the study of rocket engines plumes with the above-mentioned methods and reveals the feasibility of the measurement techniques applied.

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“…The center of the nozzle exit is selected as the origin of the xyz-coordinate system; the nozzle exits are then located downward in the negative z-axis. The x-axis is located (a) Circular nozzle [24]; (b) Square nozzle [25]. between camera No.…”

Section: Micro Nozzles and Coordinate Systemmentioning

confidence: 99%

Multi-Schlieren CT Measurements of Supersonic Microjets from Circular and Square Micro Nozzles

Nazari¹,

Ishino²,

Ishiko³

et al. 2020

JFCMV

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Instantaneous three-dimensional (3D) density distributions of a shock-cell structure of perfectly and imperfectly expanded supersonic microjets escaping into an ambient space are measured. For the 3D observation of supersonic microjets, non-scanning 3D computerized tomography (CT) technique using a 20-directional quantitative schlieren optical system with flashlight source is employed for simultaneous schlieren photography. The 3D density distributions data of the microjets are obtained by 3D-CT reconstruction of the projection's images using maximum likelihood-expectation maximization. Axisymmetric convergent-divergent (Laval) circular and square micro nozzles with operating nozzle pressure ratio 5.0, 4.5, 4.0, 3.67, and 3.5 have been studied. This study examines perfectly expanded, overexpanded, and underexpanded supersonic microjets issued from micro nozzles with fully expanded jet Mach numbers M j ranging from 1.47 -1.71, where the design Mach number is M d = 1.5. A complex phenomenon for free square microjets called axis switching is clearly observed with two types "upright" and "diagonal" of "cross-shaped". The initial axis-switching is 45˚ within the first shock-cell range. In addition, from the symmetry and diagonal views of square microjets for the first shock-cells, two different patterns of shock waves are viewed. The shock-cell spacing and supersonic core length for all nozzle pressure ratios are investigated and reported.

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Rainbow schlieren measurements in underexpanded jets from square supersonic micro nozzles

Cited by 4 publications

References 8 publications

Three-dimensional reconstruction of a microjet with a Mach disk by Mach–Zehnder interferometers

Three-dimensional reconstruction of a microjet with a Mach disk by Mach–Zehnder interferometers

Optical Diagnostics for Solid Rocket Plumes Characterization: A Review

Multi-Schlieren CT Measurements of Supersonic Microjets from Circular and Square Micro Nozzles

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