Sharif Digital Repository

In this thesis, a numerical analysis of micro chamber filling in centrifugal microfluidics is investigated. In the development of micro total analysis systems, it is often necessary to achieve complete and uniform filling of relatively large micro chambers. With centrifugal devices, these large micro chambers must often be orientated perpendicularly to the direction of centrifugal force and are usually bounded by materials with varying surface properties. On the other hand, the mixing characterization of two fluid by centrifugal microfluidic method has been also conducted. The multiphase flow analyses based on Eulerian-Eulerian approach have been conducted and the VOF method was used for ... 

In this research, a novel quasi-3D design method is developed for the centrifugal compressor impeller on the blade-to-blade plane. In this method, an iterative inverse design method called Ball-Spine Algorithm (BSA) is incorporated into the quasi-3D analysis code solving the Euler equations on the blade-to-blade and meridional planes at each shape modification step. In design procedure, the difference between the target and current pressure distribution along the suction or pressure sides of the impeller causes the blade-to-blade profile to be changed and the target pressure distribution to be satisfied. In order to validate the quasi-3D analysis code, the centrifugal compressor of a gas... 

Duct Inverse design problems usually involve finding the wall shape associated with a prescribed distribution of wall pressure or velocity. In this investigation, a novel iterative inverse design method is presented and developed for internal flows. In the proposed method, the duct walls shape is changed under a novel algorithm based on the deformation of a virtual flexible string in flow. The deformation of the string due to the local flow conditions resulting from changes in wall geometry is observed until the target shape satisfying the prescribed wall’s pressure distribution is reached. The flow field at each step is analyzed to obtain the current pressure distribution along the wall.... 

In this project, two centrifugal microfluidic platforms with the goal of separation and genetical study of circulating tumor cells have been designed, simulated and fabricated. Circulating tumor cells are the ones that are detached from the cancer tumors, entered the blood and disseminated the danger of cancer through other parts of the body. Both passive and active methods of separation are investigated in this study. The passive method is based on the inertial effects of the fluid and the active method is based on the magnetophoretic force exerted from an external magnetic field. In order to use the active method, the magnetic nanoparticles are attached to the breast cancer cells by the... 

Industrial centrifuge fans operate in various industries, specifically heavy industries such as pelletizing plants, steel mills, and cement plants. These fans transfer process gas in the production cycle. In some cases, due to their off-design working conditions, asymmetrical wear and failure happen on one side of the impeller's blades more than the other side. The most important reason is the heterogeneity of the entrance fluid's properties. One of the many critical parameters in this issue is the asymmetric distribution of particles between the two entrances of the fan. This research investigates the asymmetric erosion problem of a specific centrifugal fan with a double-suction side... 

Cancer diagnosis area has recently been in the limelight of the medical research and there exist an unremitting focus on the devices & technologies which enable cancer detection in its victims. Lately a genius diagnostic method based on isolation and entrapment of circulating tumor cells has been developed which pave the path for cancer identification. These circulating cells which are detached from the primary tumor are carried out through body by means of circulation system. They play key role in phenomenon called metastasis. Separating these rare cells from multifarious background blood cells, assessing their quantity can supply valuable information on the stage of disease as well as its... 

Centrifugal compressors are vastly implemented in the industry due to their higher pressure ratio per stage. So, researches are still going on to improve the performance of these devices. On this way, the current project is defined to perform geometrical optimization in the impeller of a centrifugal compressor using numerical and experimental methods. In this research, the design process of centrifugal compressors is first discussed according to methods and guidelines provided in several references. Then the compressor of the GT4082 turbocharger is redesigned using these theories. It is shown that overall available rules are enough to design an acceptable centrifugal compressor. Experimental... 

Pumps are widely used in oil and gas industry. Therefore condition monitoring for this type of equipment is very important. The motor current signature analysis (MCSA) technique as one of the condition monitoring techniques is very effective in the industry, but it is less used in industry. All conventional methods require additional sensors to be installed in the system; current signature analysis as a sensorless method can reduce the cost of condition monitoring. In this study, motor current signature analysis technique was used to diagnosis a centrifugal pump with a capacity of 187 kW from the refinery industry. The impeller wearing ring clearance problem has been investigated. This... 

Gas turbines and centrifugal compressors are the preferred means of compressing the gas in pipeline systems. Both gas turbines and centrifugal compressors exhibit performance characteristics that depend on the operating point imposed on them by the pipeline operation. Simulation of gas turbine-driven centrifugal compressors is necessary for a variety of applications in the general area of pipeline simulation. This research focuses on modeling of twin shaft gas turbine dynamic and steady state performance. For this purpose, it was necessary to evaluate the thermodynamic working process of the gas turbine by using an in-house computer code. At design point, the calculations are solely based on... 

The present work has been planned to elaborately investigate the key parameters which affect the formation of shrinkage porosities during centrifugal casting of ductile cast iron pipes. The porosity defects can be mostly found in the Hot Mould centrifugal casting products and adversely affect the final mechanical properties of ductile iron pipes namely Ultimate Tensile Strength and Elongation.
In the first point of view, the created defects were detected through microstructural observations and the corresponding responsible mechanisms were also discussed. The results showed that the inner porosity is produced because solidification occurs from both the inner and outer surfaces... 

A Specific process centrifugal compressor is upgraded. The operating range and efficiency pattern are increased. A one-dimensional performance prognosis tool (CCPP) is developed. The tool uses mean streamline method as the analysis model. Since the working media has various components, a complete equation of state is utilized to model the thermodynamic behavior of the real gas in super critical pressures. The performance of the base-line compressor is deyermined. The performance prognosis tool is validated with available experimental data. Upgrade road map and methodology were introduced in accordance to domestic requirements. The performance of the upgraded compressor is investigated and... 

Diabetes mellitus is a global endemic that is rapidly increasing prevalence in both developing and developed countries. Recently, the American Diabetes Association has recommended the hemoglobin A1c as a possible substitute to fasting blood glucose for diagnosis of diabetes because it is an indicator of long-term glycemic control. Also, centrifugal microfluidics systems have a good potential to be used in the point of care testing systems. In this study, two centrifugal microfluidic discs were designed and manufactured in order to separately measure the hemoglobin and hemoglobin A1c in the whole blood. In the first part of the study, the hemoglobin measurement disc consists of two chambers... 

The performance of centrifugal compressors deviates from its best design point and reaches lower efficiencies by time and conversion of input gas properties such as the pressure, temperature, and mixture characteristics. By the fact that each designed compressor should have a wide range of functionality, redesign and optimization processes take place. One of the challenging methods for improving the performance of centrifugal compressors is to modify aerodynamic passage of gas in impellers in order to achieve better pressure ratio and efficiency. The aims of the current study are to evaluate geometry properties of the blades of the first or the second impeller and even the whole compressor... 

The heart is a vital part of the body whose primary function is to pump blood throughout the body. The world's leading cause of deaths is due to heart problems. Today, most countries invest heavily in solving these problems and preventing the resulting deaths. One solution for patients with advanced heart disease is to use ventricular assist devices. This device is Used in parallel to the patient's heart, completely or partially replaces the normal functioning of the heart and provides much of the blood needed by the body. The purpose of this study is to design, manufacture and parametrically optimize a ventricular assist pump and its driver system. Since blood is clotted in contact with... 

The surge phenomenon, as the most important aerodynamic instability, has caused a severe drop in efficiency and performance in centrifugal compressors, and its prevention and control is considered one of the main concerns of industrialists. The purpose of this study is to design and develop a surge control system in order to improve the stability and safety of the system under the effect of surge. In this research, after simulating the existing control system and working line in Borzouyeh Petrochemical Industry, by designing and adding the piston surge active control system to the above centrifugal compressor and using the combined control system, the flow rate of the bypass path has been... 

Radial Flow compressors have broad applications in aero-space, transport, gas and oil industries and etc. This type of compressor is a better choice in meeting constraints on weight and space, especially when continuous high pressure stream in low volumetric rate is of interest.
Through main components of radial flow compressors, many investigations have been performed on design and optimization of the impellers and the diffusers, but the optimum design and optimization of compressor volute have received less attention.Volute design has direct and strong influence on compressor performance and its stable operating range.
In this research numerical and experimental investigations is... 

In this research, first, the performance map and surge line of 46M6 and 46MB8 multi-stage radial compressors, which have 6 and 8 stages, respectively, have been estimated and invarianted. Invarianting the performance map makes the performance curve and surge line of the compressor, unchanged from input conditions, including molecular weight, which is very important for control systems. Then, the hydrodynamic circuit of Compressor System C-3002 of Nouri Petrochemical Company was modeled according to the characteristics of its components by solving equations in MATLAB software. main working condition of the hydrodynamic circuit is close to Start of Life operating condition which has a... 

The seismic behavior of pile-supported systems has been an active area of research over the past decades. However, focus has mostly been on evaluating the seismic response of structures embedded in either dry or fully saturated, especially liquefying soil conditions. In this study, a series of dynamic centrifuge tests have been conducted to investigate the effects of soil’s degree of saturation on the seismic behavior of pile-supported superstructures. The scaled physical model tests were carried out on two distinct pile-mass systems embedded in uniform sand layers. A steady state infiltration technique was used to control matric suction profiles in the sand layer prior to shaking. The... 

Pump operating problems may be either hydraulic or mechanical and there is interdependence between the failure diagnoses of these two categories. Consequently, a correct diagnosis of a pump failure needs to consider many symptoms including hydraulic or mechanical causes. Nonlinear, time-varying behavior, and imprecise measurement information of the systems makes it difficult to deal with pump failures with precise mathematical equations, while human operators with the aid of their practical experience can handle these complex situations, with only a set of imprecise linguistic if-then rules and imprecise system states, but this procedure is time consuming and needs the knowledge of human... 

There is an increasing interest and use of energy foundations worldwide. Heat transfer from/to energy piles may cause plastic contraction of soft clay with a low overconsolidation ratio (OCR) during heating and cooling. This can influence pile-soil interaction due to thermally induced excess pore water pressure and changes of lateral stress acting on the pile.These thermally induced phenomena cause additional plastic settlement of the soil and pile. The irreversible settlement may cause serviceability or even ultimate limit state problems for floating energy piles whose capacity is mainly derived from shaft resistance. Due to intended operational needs or by accident, cyclic non-symmetrical...