Sharif Digital Repository

In this thesis, the dynamic behavior of a pinned-pinned fractional viscoelastic pipe conveying fluid is examined in the external cross flow. The Galerkin method is employed to discretize the nonlinear coupled equations of motion for viscoelastic pipe conveying fluid in the external cross flow. Consequently, four modes of system are obtained. In addition, direct perturbation method of multiple scale is used to solve the governing nonlinear coupled equations of motion for the fractional viscoelastic pipe conveying pulsating fluid in the external cross flow. Moreover, time response diagrams are drawn in order to investigate under effects of the internal fluid velocity, external fluid reduced... 

Two phase cross flows around a body have seldom been studied until now and considering these flows can play a significant role in long-term reliability and safety of industrial systems. In this paper flow regimes, drag coefficient and void fraction around different cross-section prisms were considered. To achieve this aim, main equations of flow have been developed for investigation of drag coefficient in air-water two phase. Our numerical analyses were performed by a designed and written CFD package which is based on Eulerian-Eulerian approach. Geometries, which have been studied in this article, are: circle, rectangle and triangle, for different aspect ratio and leading edge angle,... 

In the present research, a test stand for investigating the behavior of an injected jet in cross flow, is established. In All experiments water and air was used as injected jet and cross flow respectively. At the beginning, with help of dimensional analysis, non-dimensional parameters are introduced and their effect of these parameter on the jet behavior, as the most important goal of this research, is investigated. In order to inject the fluid in the cross flow, two injector with 0.58 mm and 1.08 mm exit diameter and 10 mm exit length was used, and jet speed varies from 2 m/s to 12 m/s. The cross section of the wind tunnel was a 8cm-edge-square and the air speed was adjustable in the range... 

Today’s Missiles are very maneuverable and to increase this ability, side jets are used. Beneficial usages of such systems are in fast responding and more accuracy in response of forces and moments to change directions. In jet in cross flow interactions, boundary layer is separated in front of the jet creating horseshoe vortices plus compression and expansion waves. In this research, we have developed a CFD code to simulate this flow, using the Spalart-Allmaras turbulence model and parallel computing. Then, we have studied the influence of free stream Mach number and momentum ratio. In this simulation, 2 million nodes were used in the computational domain. Also parallel processing with... 

During the brewing process, beer alternately goes through different chemical and biochemical reactions and solid–liquid separation stages. The clarification at the final step of brewing is a highly critical stage when it comes to producing a clear and bright beer. Recently, membrane technology has been successfully used in beer clarification, wherein Kieselguhr (diatomaceous earth) filtration is replaced by cross-flow microfiltration. The most important disadvantages of using microfiltration in clarification of beer is the fouling and flux decline during the process. The phenomenology of fouling mechanisms is still undefined and selection of an appropriate technique for flux enhancement in... 

Injection of liquid fuel in the cross-flowing air provides a means of higher penetration, rapid mixing of liquid fuel and air, and is encountered in many engineering applications. Air-breathing propulsion systems (e.g. gas turbine combustors, ramjets, and scramjets), liquid rocket engines,cooling sprays for turbine blades, and injection of fuel in the afterburners are examples of such applications. The identification of microscopic characteristics is one of the basic methods of atomizer examination, which has not been taken into account due to inadequate experimental equipment. In the present study, droplet mono-frame velocimetry and size distribution of secondary atomization in a pressure... 

This work deals with the computational investigation of film cooling technique, which is one the best practical way to protect gas turbine components form high thermal loads. In this regards, previous works are extensively reviewed and most important effective parameters are classified into three general categories, as geometrical parameters, flow characteristics, and physical surface factors. Each of these categories is then divided into subcategories and more details studies of each are performed. Then, a novel near-wall flow control technique of using staggered arrangement of small injection ports near a film cooling hole (combined-triple-jet; CTJ) is introduced. The fluid injected from... 

The purpose of this project is investigating the effect of cross flow and electric field on a liquid simple-jet experimentally. In this research the effect of parameters such as liquid to air momentum ratio, electric field on jet trajectory, penetration and the lenght of breakup point with respect to the jet outlet were studied. The air was produced by a blower in a duct with square test section of 8 cm sides. The air velocity varied from 1 m/s to 11 m/s. Liquid ethanol was injected into the duct with a needle with outer diameter of 0/62 mm and inner diameter of 0.4 mm and 28 mm length. The velocity of jet was 0/62 m/s while the change of liquid to air momentum ratio was from 3 to 260 The... 

In this thesis, elliptical liquid jet breakup in crossflow has been investigated. To do this, two elliptical nozzle with different aspect ratio were built. First, the effective and important dimensionless numbers were extracted. Then, the physical aspect of the question was analyzed. All the experiments have been done in atmospheric conditions with water fluid, air as the liquid jet, and gas crossflow respectively.To create crossflow, a square cross section channel and one blower which are set in the beginning of the channel were made use of. Water is injected into air crossflow by the injector installed under the channel. The system used in revealing the crossflow is shadowgraphy system.... 

Injecting liquid fuel into the cross flow of air provides high penetration of the liquid, rapid mixing with air, and increased efficiency. This method has widespread applications in the propulsion systems of gas turbines, scramjets, turbine blade cooling, and fuel injection for engine afterburners. One of the design strategies for future aircraft engines is to reduce pollutants using fuel spray into the cross flow instead of direct jet fuel injection and using renewable energy sources. The applications of cross flows include injecting fluid through rotating pressure injectors in exhaust flows, injecting fluid through pressure-rotating injectors in radial injectors, and using slinger...