Special Issue "Advanced Flow Diagnostic Tools"

A special issue of Aerospace (ISSN 2226-4310). This special issue belongs to the section "Aeronautics".

Deadline for manuscript submissions: 31 October 2023 | Viewed by 13039

Special Issue Editor

1. Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing 100190, China
2. University of Chinese Academy of Sciences, Beijing 100049, China
Interests: supercritical fluids; advanced measurement techniques; energy; multiscale transport phenomena

Special Issue Information

Dear Colleagues,

The turn of the century has seen tremendous progress in flow diagnostic tools as a result of the even more staggering improvement in optical illumination, detection devices, as well as data processing techniques. For instance, advances in laser-based optical methods over the last 40 years, including PIV, LDA, PSP/TSP, PLIF, FLEET, Rayleigh Scattering, etc., have made major breakthroughs in the analysis of complex flows containing shock waves, strong expansions, shear layers, vortex organizations, and recirculation regions. There are still many other advanced flow diagnostic technologies that have emerged in aerodynamics and have been widely used in the automobile, aircraft, propulsion, and turbomachinery industry. Although those methods are still under development, they are also opening new possibilities for the measurement and analysis of flow fields that seem too difficult (or even impossible) to achieve using conventional techniques.

This Special Issue will be a collection of contributions that reflect the latest efforts in the development and application of advanced and/or novel flow diagnostic tools with potential applications (or directly linked) to wind tunnel and flight tests, combustion flow, multiphase flow, heat transfer flow, etc. Suitable topics include but are not limited to:

  • Laser-based optical measurement techniques;
  • Flow visualization techniques;
  • Non-intrusive measurement of pressure, skin friction, heat transfer, and deformation at the surface;
  • Advanced measurement methods of aerodynamic forces and moments (magnetic suspension balance and cryogenic balance);
  • Flow diagnostic tools under extreme conditions (ultra-high-speed, low/high temperature; space condition, etc.);
  • Advanced data processing methods for flow diagnostic tools.

Dr. Lin Chen
Guest Editor

Manuscript Submission Information

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Keywords

  • Laser-based optical methods
  • Surface flow visualization
  • Transition detection
  • Microfluidics/nanofluidics
  • Combustion flow
  • Multiphase flow
  • Wind tunnel and/or flight tests
  • Heat transfer flow
  • Boundary layer
  • Compressible flow

Published Papers (6 papers)

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Research

Communication
Wake-Tailplane Interaction of a Slingsby Firefly Aircraft
Aerospace 2022, 9(12), 787; https://doi.org/10.3390/aerospace9120787 - 02 Dec 2022
Viewed by 591
Abstract
This paper presents in-flight measurements of the interaction of the wing wake of a stalled Slingsby T67 Firefly light aircraft with the aircraft tailplane. Tailplane data was recorded by a GoPro360 camera and analyzed using spatial correlation methods. The tailplane movement and corresponding [...] Read more.
This paper presents in-flight measurements of the interaction of the wing wake of a stalled Slingsby T67 Firefly light aircraft with the aircraft tailplane. Tailplane data was recorded by a GoPro360 camera and analyzed using spatial correlation methods. The tailplane movement and corresponding spectra indicate that the aerodynamic wake shedding frequency closely matches the resonant frequency of the tailplane, resulting in a significant excitation of the structure during heavy stall. Large magnitude, lower frequency tailplane movement was also identified by analysis of the pitch attitude from the image data, with results consistent in post-stall behavior reported by previous modelling and measurements. Full article
(This article belongs to the Special Issue Advanced Flow Diagnostic Tools)
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Article
Digitalization and Quantitative Flow Visualization of Surrounding Flow over a Specially-Shaped Column-Frame by Luminescent Mini-Tufts Method
Aerospace 2022, 9(9), 507; https://doi.org/10.3390/aerospace9090507 - 11 Sep 2022
Viewed by 973
Abstract
The luminescent mini-tufts method is widely used for flow visualization for quantitative field analysis. A set of numerical methods for digitalization of 3D surfaces surrounding flows with luminescent mini-tufts has been developed in this study. The procedure includes digital image pre-processing, mini-tufts recognition, [...] Read more.
The luminescent mini-tufts method is widely used for flow visualization for quantitative field analysis. A set of numerical methods for digitalization of 3D surfaces surrounding flows with luminescent mini-tufts has been developed in this study. The procedure includes digital image pre-processing, mini-tufts recognition, mean field mini-tufts calculation, inclination angle calculation, oscillation area calculation, etc. The model is subjected to a newly proposed digitalization method and realized by in-house code. The time mean angle’s changing mode, along the mini-tuft, are analyzed, which shows that the mini-tuft follows the inflow well. The transient oscillation of mini-tufts is observed as well, which shows that on the middle part of the irregularity cylinder, the flow oscillates more intensively. Full article
(This article belongs to the Special Issue Advanced Flow Diagnostic Tools)
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Article
Identification Strategy Design with the Solution of Wavelet Singular Spectral Entropy Algorithm for the Aerodynamic System Instability
Aerospace 2022, 9(6), 320; https://doi.org/10.3390/aerospace9060320 - 13 Jun 2022
Cited by 2 | Viewed by 1122
Abstract
In order to effectively identify the signs of instability in the aerodynamic system of an axial compressor, a wavelet singular spectral entropy algorithm incorporated within the wavelet transform, singular value decomposition and information entropy is proposed to describe the distribution complexity of the [...] Read more.
In order to effectively identify the signs of instability in the aerodynamic system of an axial compressor, a wavelet singular spectral entropy algorithm incorporated within the wavelet transform, singular value decomposition and information entropy is proposed to describe the distribution complexity of the spatial modalities in the flow field. This kind of identification design can accurately distinguish the boundary between the stable and unstable states of the internal flow field from the view of a dynamic system. On the basis of the information entropy algorithm, the wavelet singular spectral entropy algorithm is designed to integrate with the advantages of wavelet transform analysis on the time-frequency localization and singular value decomposition for signal processing and data mining together. So that the quantitative analysis of the definition of rebuilding a system image can be achieved by the solution of wavelet singular spectral entropy. This method can automatically extract the transient information of the space mode in the time-frequency domain. It effectively avoids the shortcoming that the feature extraction on spatial information cannot be accomplished from multiple angles with the single information entropy algorithm. In the data processing of instability signals under different speeds, the wavelet singular spectral entropy algorithm shows a greater advantage in the early warning for compressor stall. The result shows that the value of the wavelet singular spectral shows an obvious mutation when the aerodynamic system approaches the instability boundary. According to the threshold set, the identification hybrid algorithm can detect the stall precursor about 23~96 r in advance. Compared to the single information entropy algorithm, the hybrid wavelet singular spectral entropy algorithm is able to shift to an earlier precursor identification by about 11~82 r. This established hybrid identification algorithm accounts for the nonlinearity of the aerodynamic system, providing a new perspective for the nonlinear system instability identification. Full article
(This article belongs to the Special Issue Advanced Flow Diagnostic Tools)
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Article
Simultaneous Pressure and Displacement Measurement on Helicopter Rotor Blades Using a Binocular Stereophotogrammetry PSP System
Aerospace 2022, 9(6), 292; https://doi.org/10.3390/aerospace9060292 - 27 May 2022
Cited by 2 | Viewed by 1516
Abstract
A simultaneous surface pressure and displacement measurement method that integrates pressure-sensitive paint (PSP) and binocular stereophotogrammetry is proposed. The assays were completed on the Φ4 m rotor test stand at China Aerodynamic Research and Development Center (CARDC). A single-shot lifetime approach was utilized [...] Read more.
A simultaneous surface pressure and displacement measurement method that integrates pressure-sensitive paint (PSP) and binocular stereophotogrammetry is proposed. The assays were completed on the Φ4 m rotor test stand at China Aerodynamic Research and Development Center (CARDC). A single-shot lifetime approach was utilized to acquire the instantaneous pressure field on a rotor blade coated with PSP. At the same time, the PSP feature points were used to obtain the 3D coordinates of stereo cameras, which yielded the blade displacement field. The experimental results showed that the displacement measuring accuracy was better than 0.2 mm, and the pressure measurement accuracy was not affected, with Standard Deviation (STD) values below 700 Pa. The advantages of the proposed system are its simple structure, low cost, high accuracy and high test efficiency, which will offer a practical solution for the exploration of fluid–structure interplay. Hence, such a system is a prospective for the wind tunnel tests of helicopter rotor blades. Full article
(This article belongs to the Special Issue Advanced Flow Diagnostic Tools)
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Article
Combustion Characteristics of a Supersonic Combustor with a Large Cavity Length-to-Depth Ratio
Aerospace 2022, 9(4), 214; https://doi.org/10.3390/aerospace9040214 - 14 Apr 2022
Cited by 4 | Viewed by 1409
Abstract
The combustion characteristics of a hydrogen-fueled supersonic combustor featuring a large cavity length-to-depth ratio (i.e., 11) were examined by performing experimental trials while varying the fuel injector positions and equivalence ratios. During these trials, flame chemiluminescence images were acquired simultaneously from the side [...] Read more.
The combustion characteristics of a hydrogen-fueled supersonic combustor featuring a large cavity length-to-depth ratio (i.e., 11) were examined by performing experimental trials while varying the fuel injector positions and equivalence ratios. During these trials, flame chemiluminescence images were acquired simultaneously from the side and bottom of the combustor under Mach 2.0 inflow conditions. The flame was observed to stabilize inside the cavity under all conditions. Proper orthogonal decomposition (POD) and dynamic mode decomposition (DMD) analyses of sequential flame chemiluminescence images demonstrated the important effects of oblique shocks induced by fuel injection and heat release on flame stabilization. Because fluctuations in the locations of the flame and of the intense heat release zone were not observed and no dominant frequency was identified in POD and DMD analyses, the present configuration was evidently able to suppress combustion instability. The present research provides preliminary guidance for exploring the feasibility of using cavity combustors with large length-to-depth ratios in scramjet engines. Full article
(This article belongs to the Special Issue Advanced Flow Diagnostic Tools)
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Article
Design of a High Uniformity Laser Sheet Optical System for Particle Image Velocimetry
Aerospace 2021, 8(12), 393; https://doi.org/10.3390/aerospace8120393 - 10 Dec 2021
Cited by 1 | Viewed by 2058
Abstract
Particle image velocimetry (PIV) is a non-contact, instantaneous and full-flow velocity measurement method based on cross-correlation analysis of particle image. It is widely used in fluid mechanics and aerodynamics. Laser sheet optical system is one of the key equipment of PIV, and it [...] Read more.
Particle image velocimetry (PIV) is a non-contact, instantaneous and full-flow velocity measurement method based on cross-correlation analysis of particle image. It is widely used in fluid mechanics and aerodynamics. Laser sheet optical system is one of the key equipment of PIV, and it is an important guarantee to obtain high definition particle image. In the PIV measurement task of large low speed wind tunnel, in order to solve the problem of sheet light illumination uniformity of large size model and take into account the requirements of PIV technology on the thickness of the sheet light, a hybrid algorithm is used to design a high uniformity laser sheet optical system based on the theory of physical optics. The simulation results show that the size of the sheet light is 400 mm × 1 mm, the diffraction efficiency reaches 97.77%, and the non-uniformity is only 0.03%. It is helpful to acquire high-resolution images of particles in the full field of view. It also can be applied to a series of non-contact flow field measurement techniques such as plane laser induced fluorescence, filtered Rayleigh scattering and two-color plane laser induced fluorescence temperature measurement. Full article
(This article belongs to the Special Issue Advanced Flow Diagnostic Tools)
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