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The wake flow characteristics of a 1:20 scale articulated lorry model with a linear Alternate Current Dielectric Barrier Discharge (AC-DBD) plasma actuation implemented was experimentally investigated. Time-averaged velocity, turbulence, and vorticity information along the centreline of the model were constructed using a two-component particle image velocimetry technique. In addition, force balance was used to measure the time-average drag force acting on the model with and without the use of AC-DBD plasma actuation. In general, the AC-DBD plasma actuation showed negligible effect in changing the drag coefficient of the test model. Moreover, implementing the AC-DBD plasma actuation around the rear end of the trailer model could neither alter the size nor the reverse flow velocity in the wake region. In contrast, the AC-DBD plasma actuation increased the levels of fluctuation in the flow turbulence kinetic energy and vorticity but showed no observable effect to alter the frequency response of the flow in the wake region. It is deduced that the use of AC-DBD plasma actuation indeed generated no flow control effect at the rear end of an articulated lorry trailer.
Kin-Hing Lo; Rengarajan Sriram; Konstantinos Kontis. Wake Flow Characteristics over an Articulated Lorry Model with/without AC-DBD Plasma Actuation. Applied Sciences 2019, 9, 2426 .
AMA StyleKin-Hing Lo, Rengarajan Sriram, Konstantinos Kontis. Wake Flow Characteristics over an Articulated Lorry Model with/without AC-DBD Plasma Actuation. Applied Sciences. 2019; 9 (12):2426.
Chicago/Turabian StyleKin-Hing Lo; Rengarajan Sriram; Konstantinos Kontis. 2019. "Wake Flow Characteristics over an Articulated Lorry Model with/without AC-DBD Plasma Actuation." Applied Sciences 9, no. 12: 2426.
An experimental study has been conducted to visualise the instantaneous streamwise and spanwise flow patterns of a normal shock wave impinging over a rounded contour bump in a Mach 1.3 free-stream. A quartz-made transparent shock generator was used, so that instantaneous images could be captured during the oil-flow visualisation experiments. Fluorescent oil with three different colours was used in the surface oil-flow visualisation experiment to enhance the visualisation of flow mixing and complicated flow features that present in the flow field. Experimental data showed that the rounded contour bump could split the impinging normal shock wave into a or a series of lambda-shaped shock wave structure(s). In addition, it was found that the flow pattern and the shock wave structures that appeared over the rounded contour bump depended highly on the impinging location of the normal shock wave. The flow pattern shown in this study agreed with the findings documented in literature. Moreover, it was observed from the instantaneous oil streaks that the normal shock impinging location also affected the size and the formation location of the spanwise counter-rotating vortices downstream of the bump crest. Finally, it was concluded that the terminating shock could distort the oil streaks that left over the surface of the contour bump. Therefore, the use of the transparent normal shock wave generator is recommended when conducting experiments with normal shock wave impingement involved.
Kin Hing Lo; Konstantinos Kontis. Flow visualisation of a normal shock impinging over a rounded contour bump in a Mach 1.3 free-stream. Journal of Visualization 2016, 20, 237 -249.
AMA StyleKin Hing Lo, Konstantinos Kontis. Flow visualisation of a normal shock impinging over a rounded contour bump in a Mach 1.3 free-stream. Journal of Visualization. 2016; 20 (2):237-249.
Chicago/Turabian StyleKin Hing Lo; Konstantinos Kontis. 2016. "Flow visualisation of a normal shock impinging over a rounded contour bump in a Mach 1.3 free-stream." Journal of Visualization 20, no. 2: 237-249.
Flow separation control over a three-dimensional contour bump using jet in a Mach 1.9 supersonic free-stream has been experimentally investigated using a transonic/supersonic wind tunnel. Jet total pressure in the range of 0 bar to 4 bar was blowing at the valley of the contour bump. Schlieren photography, surface oil flow visualization and particle image velocimetry measurements were employed for flow visualization and diagnostics. Experimental results show that blowing jet at the valley of the contour bump can hinder the formation and distort the spanwise vortices. The blowing jet can also reduce the extent of flow separation appears downstream of the bump crest. It was observed that this approach of flow control is more effective when high jet total pressure is employed. It is believed that a pressure gradient is generated as a result of the interaction between the flow downstream of the bump crest and the jet induced shock leads to the downwards flow motion around the bump valley.
Kin Hing Lo; Hossein Zare-Behtash; Konstantinos Kontis. Control of flow separation on a contour bump by jets in a Mach 1.9 free-stream: An experimental study. Acta Astronautica 2016, 126, 229 -242.
AMA StyleKin Hing Lo, Hossein Zare-Behtash, Konstantinos Kontis. Control of flow separation on a contour bump by jets in a Mach 1.9 free-stream: An experimental study. Acta Astronautica. 2016; 126 ():229-242.
Chicago/Turabian StyleKin Hing Lo; Hossein Zare-Behtash; Konstantinos Kontis. 2016. "Control of flow separation on a contour bump by jets in a Mach 1.9 free-stream: An experimental study." Acta Astronautica 126, no. : 229-242.
An experimental study has been conducted to investigate the static and wind-on performance of two in-house-developed polymer-based pressure-sensitive paints. Platinum tetrakis (pentafluorophenyl) porphyrin and tris-bathophenanthroline ruthenium II are used as the luminophores of these two polymer-based pressure-sensitive paints. The pressure and temperature sensitivity and the photo-degradation rate of these two pressure-sensitive paints have been investigated. In the wind tunnel test, it was observed that the normalised intensity ratio of both polymer-based pressure-sensitive paints being studied decreases with increasing the number of wind tunnel runs. The exact reason that leads to the occurrence of this phenomenon is unclear, but it is deduced that the luminophore is either removed or deactivated by the incoming flow during a wind tunnel test.
Kin Hing Lo; Konstantinos Kontis. Static and Wind-on Performance of Polymer-Based Pressure-Sensitive Paints Using Platinum and Ruthenium as the Luminophore. Sensors 2016, 16, 595 .
AMA StyleKin Hing Lo, Konstantinos Kontis. Static and Wind-on Performance of Polymer-Based Pressure-Sensitive Paints Using Platinum and Ruthenium as the Luminophore. Sensors. 2016; 16 (5):595.
Chicago/Turabian StyleKin Hing Lo; Konstantinos Kontis. 2016. "Static and Wind-on Performance of Polymer-Based Pressure-Sensitive Paints Using Platinum and Ruthenium as the Luminophore." Sensors 16, no. 5: 595.
In the field of aerospace engineering, the study of the characteristics of vortical flows and their unsteady phenomena finds numerous engineering applications related to improvements in the design of tip devices, enhancement of combustor performance, and control of noise generation. A large amount of work has been carried out in the analysis of the shock wave diffraction around conventional geometries such as sharp and rounded corners, but the employment of splitters with lateral variation has hardly attracted the attention of researchers. The investigation of this phenomenon around two-dimensional wedges has allowed the understanding of the basic physical principles of the flow features. On the other hand, important aspects that appear in the third dimension due to the turbulent nature of the vortices are omitted. The lack of studies that use three-dimensional geometries has motivated the current work to experimentally investigate the evolution of the shock wave diffraction around two splitters with spike-shaped structures for Mach numbers of 1.31 and 1.59. Schlieren photography was used to obtain an insight into the sequential diffraction processes that take place in different planes. Interacting among them, these phenomena generate a complicated turbulent cloud with a vortical arrangement.
Francesca Gnani; Kin Hing Lo; Hossein Zare-Behtash; Konstantinos Kontis. Shock Wave Diffraction Phenomena around Slotted Splitters. Aerospace 2015, 2, 1 -16.
AMA StyleFrancesca Gnani, Kin Hing Lo, Hossein Zare-Behtash, Konstantinos Kontis. Shock Wave Diffraction Phenomena around Slotted Splitters. Aerospace. 2015; 2 (1):1-16.
Chicago/Turabian StyleFrancesca Gnani; Kin Hing Lo; Hossein Zare-Behtash; Konstantinos Kontis. 2015. "Shock Wave Diffraction Phenomena around Slotted Splitters." Aerospace 2, no. 1: 1-16.