Experimental investigation of surface flow pattern on truncated cones in Mach 5 flow: influence of truncation ratio

The flow characteristics on a truncated cone with a cylinder were experimentally investigated in a Mach 5 flow with a Reynolds number 3.8 × 105, based on the cylindrical diameter. Two different truncation ratios of 0.5 and 0.7 were used. The incidence angle varied from −12 to 0° with 3° intervals to investigate the influence of the truncation ratio on the surface flow pattern. The measurement techniques: unsteady pressure-sensitive paint (anodized aluminium method), color Schlieren photography, and surface oil flow were used. It was found that the distance of the external shock wave from the conical surface depends on the truncation ratio, and the surface pressure on the conical portion increases when the external shock wave moves closer to the model surface. The “external” shock wave denotes a detached shock wave and the “internal” one is the shock wave formed between the detached bow shock wave and the model surface. In the higher truncation ratio at the higher incidence angle, the internal shock wave induced by the flow separation on the conical surface impinges on the external shock wave, which results in its reflection. This reflection leads to the pressure increase on the model surface. On the other hand, this reflection does not appear in the lower truncation ratio. In spite of the different truncation ratios, the angle of the internal shock wave is identical at the same incidence angle. From the oil flow results, the wall shear stress on the leeward conical surface is lager in the higher truncation ratio model

Effectiveness of jet location on mixing characteristics inside a cavity in supersonic flow

The incorporation of cavities within supersonic combustion chambers is an effective means of slowing down the flow for fuel injection and consequent stable combustion. Understanding the flow physics associated with such flows, especially with the injection of a gas to replicate fuel injection, are essential for the optimum design of supersonic propulsion mechanisms. An experimental investigation was performed on a rectangular open cavity with upstream injection model in a Mach number of 1.9 using a trisonic indraft wind tunnel. A rectangular open cavity of dimensions L/D = 5, 100 mm in length (L) and 20 mm deep (D), was adopted, and it was embedded into the lower wall of the test section. An air jet with a jet-to-freestream momentum flux ratio of J = 1.2, 2.7 and 5.3 was injected upstream of the cavity. To evaluate the effect on mixing and flow stability the jet position, measured from the front edge of the cavity, was varied between 0.1L and 1L. The flow field was visualized using schlieren photography, particle image velocimetry, and oil flow measurements. It is found that the mixing characteristic within the cavity when the jet is positioned 0.1L is enhanced independent on the J value because the turbulence intensity of the flow velocity within the cavity is strongly influenced by the jet interaction which lifted the flow from the floor of the cavity compared to the other jet positions. However, the flow over the cavity is unstable at all jet positions. The separation shock formed at the front edge of the cavity oscillates significantly for the case where the jet is located at 0.1L because the separation shock location coincides with the compression shock behind the jet

WATER AS AN INSTRUMENT OF REMEMBRANCE: BOSPHORUS IN THE TEXTS OF RUSSIAN ÉMİGRÉ LITERATURE

Bosphorus in the general perception of Russian Émigré Literature as a component of city is the main material of this study. The aim is to find out how the texts of Russian Émigré Literature influenced the image of Bosphorus and how it was fed by the other texts. This material is studied according to the power of component on forming a city’s image. In this study the texts of Russian émigré writers, such as I. Bunin, V. Nabokov, A. Tolstoy, A. Averchenko, N. Teffi, Z. Shahovskaya, G. Kuznetsova and Don-Aminado, who were lived and wrote in the period of emigration in Istanbul, are used. As method of this study, an urban planning method for analysing cities, which is offered by Kevin Lynch, is used. This kind of interdisciplinary method gives us opportunity of seeing the power of the texts on creating the whole image of the cities with the help of components and sub-components. Separating Bosphorus from its sub-components made possible to see relation between time and water in the texts

Experimental investigation of sonic transverse jets in Mach 5 crossflow

An experimental investigation of sonic transverse jets in Mach 5 cross flow over a flat plate with a sharp leading edge was carried out. Jet to free stream momentum flux ratio, J, was varied from 1.16 to 5.30. Schlieren visualisation provided information regarding mean flow features such as Mach disc height, h, separation length, Xsep as well as inherent unsteadiness. Steady wall pressure measurements diagnosed the interaction region between the jet and the incoming cross flow developing on the flat plate. To assess the jet penetration characteristics and trajectories, two-component Particle Image Velocimetry (PIV) measurements were carried out at the centreplane of the flat plate. Raw PIV image analysis was used to specify jet penetration boundaries. Ensemble-averaged streamwise and transverse velocity contours revealed the mean flow structures. The barrel shocks and the Mach disc forming the jet boundary can be easily seen and were visualised/quantified using PIV measurement technique. Maximum turbulence occurred above the Mach disc due to the presence of the shear layer and at the intersection of the windward side of the barrel shock and bow shock