Prof. Koji OKAMOTO
Topic: Progress and Future of High-speed Quantitative Visualization
Quality of high-speed camera had been improved dramatically in this decade. Complicated phenomena under extremely severe environment can be visualized and quantized very easily. Nowadays, 100kHz sampling images with enough image resolutions are widely used. The sensitivity of the image capturing devise, e.g., C-MOS, is also improved drastically. Several applications on the high-speed imaging with quantitative evaluation will be discussed.
Particle Image Velocimetry (PIV) technique is now widely used just combining high-speed camera and CW laser sheet. Also, using the oversampled images, individual tracer trajectories have been detected with higher accuracy. Temporal oversampling may reduce the error for particle tracking, resulting in the accurate measurements.
PIV coupled with Temperature Sensitive Paint (TSP) will reveal the temperature and velocity distributions simultaneously. The functional tracer particle may also improve the techniques.
Reviewing the previous quantitative technique, the future of Quantitative Visualization will be discussed.
Prof. Choongsik BAE
Topic: Diagnostics on spray and combustion process of alternative fuels in optical engines
The depletion of conventional fossil fuels and concern of harmful pollutants have forced automobile industry to seek alternative fuels for internal combustion engines. The utilization of alternative fuels for instance liquid petroleum gas (LPG), jet propellant 8 (JP-8) and biodiesel fuels for internal combustion engines is being considered in many countries. However, component manufacturers design fuel injectors for conventional petroleum based fuels, which have different fuel properties with alternative fuels. The injector effectiveness is greatly influenced by the different fuel properties such as density, viscosity and surface tension. Furthermore, the combustion processes in spark-ignition (SI) engine and compression ignition (CI) engine are greatly affected by fuel atomization and air-fuel mixing process. Thus, there is a need to understand the effect of fuel properties on spray and combustion. In this study, spray and flame characteristics of alternative fuels were investigated based on high-speed imaging. The LPG was introduced as an alternative fuel for SI engine, meanwhile, JP-8, biodiesel and gasoline fuels were introduced as alternative fuels for CI engine. At first, spray characteristics of alternative fuels were investigated in a constant volume chamber (CVCC). The macroscopic spray process was characterized from Mie-scattering and shadowgraph images in terms of spray tip penetration length, and spray angle. For a detailed study of the spray formation in the near-nozzle region, a long-distance microscopy (LDM) was also performed. A series of engine test with alternative fuels was carried out in optically accessible engines. The engine performance and emission characteristics were compared with base fuels. Finally, flame characteristics of alternative fuels were studied based on direct high-speed imaging in optical engines.
Prof. Irina ZNAMENSKAYA
Topic: Digital Imaging in Flow Visualization and CFD simulation
Progress (revolution) in digital imaging in recent years launched the process of mutual influence of CFD and experimental flow visualization and image processing. The opportunities presented by the use of comparison of the experimental flow visualization, image processing and CFD visualization are discussed. Examples of comparison of numerical and experimental flow visualization, obtained by different imaging techniques are shown: PIV images, schlieren, BOS, thermography, discharge visualization, high speed shadowgraphy of shock waves, etc. Comparison of numerical and experimental patterns may be successfully used for CFD validation, physical process model correction, experiment improving. Digital convergence of experimental and computational visualization provides an opportunity to apply new methods of image processing to experimental data with purpose to define flow structures and to trace them with high accuracy. Application of image processing methods and CFD visualization can be also useful for elimination of experimental artifacts in results. Digital numerical and experimental flow fields visualization matching is shown to be an effective tool for the analysis of hydrodynamic processes in complex 2D and 3D non-stationary flows.
Prof. Gennaro CARDONE
Topic: Thermo-fluid-dynamic analysis by infrared thermography: a review
Infrared thermography (IRT) has been used for many years in many fields and for many different purposes. This because of its many advantages over contact transducers. In particular, it has proved its capability to deal with thermo-fluid-dynamic problems also in presence of complex fluid flow configurations. In fact, IRT is non-intrusive, has high sensitivity (down to 10mK) and fast response (up to 3kHz), is fully two-dimensional allowing for a better evaluation of errors due to radiation and tangential conduction within the heat flux sensors. By appropriate choice of the device, IRT can be exploited to resolve convective heat fluxes within both steady and transient conditions. This work would be an overview on the use of infrared thermography in thermo-fluid-dynamics. It includes: a background to the radiation theory, an overview of the main IR cameras features, a description of the pertinent heat flux sensors and an analysis of the IR image processing methods. At last, some examples of convective heat transfer measurements in also complex fluid flows, involving either very low (natural convection), or very high (hypersonic regime) speeds, are described.
Prof. Tai-Wen HSU
Topic: Application of BIV and PIV Techniques to Breaking Wave-Induced Flow Fields over Artificial Reef
This thesis use Particle Image Velocimetry (PIV) and Bubble Image Velocimetry (BIV) to measure the various complex flow phenomena surrounding an artificial reef owing to its interaction with an oncoming wave. Based on the experimental results, the wave height of progressive wave decreases gradually with the increase of the distance of artificial reef. When wave breaking, the wave take the air into water and have air bubble. The air bubble velocity constantly decrease by the bubble impact in front of water. In breaking wave, surround of waterline’s field, the velocity is more faster than surround of structure. And the scope of this phenomenon increase gradually with the increase of the distance of artificial reef.
Dr. Friedrich LEOPOLD
Topic: The influence of spin on the flow around models at supersonic speed
Many projectiles spin around their longitudinal axis during flight for advantages such as obtaining stability through the gyroscopic effect, eliminating or decreasing adverse effects caused by eccentricity, and simplifying the control system. Especially when the models are equipped with fins, the spin can induce a highly asymmetrical flow, causing a lateral force perpendicular to the angle of attack plane and a yawing moment as well as fundamental changes in the wake flow.
The lateral force and yawing moment induced by spin are referred to as the Magnus effect. These effects depend not only spin rate and angle of attack, but also body shape and fineness, Mach and Reynolds number. Any change in these parameters will lead to a different state of the boundary layer and hence affect the Magnus effect. The Magnus side force and also the moment show a nonlinear dependence on the cross-flow Mach number and thus on the angle of attack. Visualizations and numerical simulations provide a profound insight in the flow structure and reveal a shift of the separation lines as consequence of the spin. This is shown to be the primary source of the Magnus side force for higher angles of attack in the investigated range.
Secondly, the effects of swirl on supersonic wake flow are investigated. To this end, flat-based afterbody geometries, utilizing canted fins to deflect the flow circumferentially immediately upstream of the model's base corner, are used. The velocity fields in the central plane behind the models were measured using particle image velocimetry (PIV). This is supplemented by wall shear stress visualizations on the base and pressure measurements using high-frequency transducers at different radial positions on the model base. The introduction of swirl into the wake flow is shown to change the structure of the wake fundamentally compared to non-swirling wake flows. The highest introduced swirl rates in this study lead to a phenomenon in the wake similar to a vortex breakdown, which was up to date described in literature only for vortex tubes and swirling jets. Additionally, the central base pressure decreased up to 80 %. These changes are primarily dependent on freestream condition, model geometry and introduced swirl rate. Additionally conducted transient large-scale turbulence-resolving numerical simulations using the detached eddy simulation (DES) method confirm the experimental results. The simulation data furthermore show that the centrifugal volume forces introduced by the swirling flow motion are crucial to the observed changes in the wake.
Tentative program of PSFVIP-11 at a glance
Click on the time table to display a larger image.
(The figure in each session shows your paper number.)
The scientific program will include 6 keynote lectures, given by outstanding researchers on topics of broad interest to the flow visualization and image processing community, along with contributed papers, poster sessions. Over 115 contributed abstracts are anticipated.
On Friday, December 1st, 2017 the registration desk will be open from 11am to 7pm. All participants of PSFVIP-11 are invited to the Welcome Reception, which will take place on Friday, December 1st from 5:30pm until 7:00pm at the conference venue. The Welcome Reception will serve as an initial get-together for social networking in a relaxed atmosphere.
The official program will start Friday, December 1st, 2017 at 1:00pm. The conference will end Sunday, December 3rd, 2017 at 11:50am.
The official program also includes the Conference Banquet, which will be held on Saturday, December 2nd, 2017 at the Hotel MIELPARQUE Kumamoto.