Sharif Digital Repository

Jet into cross-flow interaction is one of the complex and fundamental problems in fluids dynamics and heat transfer, which is observed in various applications, such as pollutant discharges, film cooing of turbine blades, combustion chamber design of jet engines, trust vectoring systems, boundary layer control, and vertical short take-off and landing (VSTOL) aircrafts. One of the applications of this kind of flow is injection of supersonic jet into subsonic compressible cross-flow, which is used in trust vectoring systems of missiles. In this research, the two-dimensional interactions of supersonic jet into subsonic compressible cross-flow were investigated as two cases: "without a fin" and... 

The interactions between jets and cross flows appear in many engineering applications (such as film cooling) and thus their study is of great importance. In film cooling, the coolant fluid is transferred from the compressor to the surface of the turbine blades via small holes. An increase of about 170⁰C of the engine working temperature increases the engine efficiency about 5%. To reach higher temperatures of the inlet air flow, one tries to have the least amount of interactions between the film cooling jets and the the cross flow. In this work, we computationally studied turbulent film cooling of a flat plate, in which we used the combined triple jet and investigated the effects of density... 

The problem of jet into a cross flow is one of the classic problems in fluid mechanics and has many engineering applications, such as in vector thrust control systems. Although many works have been done in this field, there have not been enough research in interactions of supersonic jets into compressible subsonic cross flows (specially its interaction with control surfaces downstream). Hence, the purpose of this research is to get better understanding of this interaction and its effects on control surfaces downstream (both numerical and experimental). Some of the individual achievements of this research are the design and manufacturing of supersonic jet system, parametric study of: boundary... 

In this M.S. dissertation numerical study of slinger fuel distributer has been studied. This type of atomizer has been used in mini turbojets like Teledyne CAE.
The main purpose of this work was obtaining spray structure of slinger atomizers. This goal was achieved by implementing a UDF code in FLUENT® software to model the primary atomization that include variation of fluid from exit of slinger disk bores till formation of primary droplet. In FLUENT® the DPM method and its ability to utilizing Lagrangian approaches have been used. The result of this model is validated by the data from experimental test that can be found in Articles. This is the first time that spray structure of slinger... 

In This Study break up and trajectory of aerated liquid jet in subsonic cross flow has been investigated. An effervescent two phase flow injector has been used with two different diameters for its external orifice. The effects of non-dimensional parameters on the trajectory of aerated liquid jet were evaluated. Water was used as the fluid for the purpose of producing liquid jet. Air was used to produce gaseous phase in the injector and the cross flow as well.
A duct with a square cross section and a blower in the inlet of the duct were used to produce the cross flow. Mixture of air and water was injected into the cross flow by the injector installed at the bottom of the duct. Shadowgraph... 

In the present work, the possibility of using a cross flow microchannel heat exchanger in cryogenic service for natural gas liquefaction has been numerically investigated using 3D computational fluid dynamics approach. Microchannels of rectangular and triangular cross section with a hydraulic diameter of 0.667 and 0.472 mm respectively have been constructed in Gambit and Fluent is used as the solver of numerical simulations.For solver’s equations validation, the existing experimental data on flow of water through rectangular microchannels has been modeled by CFD. Comparison of CFD results with experimental data shows a good agreement.Both models are constructed of three distinct layers. In... 

Injection of jet into cross-flow has various applications, such as film cooling of gas turbine blades, reaction control jets for missiles and aircrafts, and mixing of air and fuel in combustion chambers. Velocity ratio (blowing ratio), momentum ratio, and streamwise jet inclination angle are important correlation parameters which have been studied extensively. However, not much work has been done on the jet swirling effects. The present work investigates computational simulation of a row of swirling square jets injected normally into a cross-flow. The swirl is introduced using two injectors discharged normally into the jet. Computational simulations were performed using LES approach with... 

Exosomes are a type of extracellular vesicles which are secreted by cells and could be found in all of human biofluids including blood. The size of exosomes is in the range of 30 – 150 nm. And they have a spherical structure with a phospholipid membrane. Exosomes are very important in academic research for the purpose of diagnostic and therapeutic practices because of their protein and nucleic acid contents.In this study a technological system was developed for isolation of circulating exosomes of human whole blood. This system consisted of a collection of microfluidic chips and protocols in order to extract a purified sample of exosomes from whole blood. First, a chip based on centrifugal... 

In this thesis, the physics related to liquid jet injection from injectors with three different crescent-shaped cross-sectional levels into steady and transverse flow were studied. The imaging method in this research was based on shadowgraph, which enables high-speed imaging. With the help of the obtained images, the breakup regimes, including Rayleigh, first and second wind-induced instabilities, were observed for injection into the steady flow. Furthermore, breakup regimes for jet injection into transverse flow, including columnar, columnar-bag, and bag, were also observed. The characteristics of the breakup height in steady flow and the length and height of the breakup along with the jet...