Sharif Digital Repository

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... 

Centrifugal compressors have wide applications in the turbochargers, aircraft propulsion and petrochemical industry. Therefore it is important to design high efficiency centrifugal compressor. Knowledge of compressor performance at different conditions, energy losses and the contribution of each component of compressor in efficiency losses have of great importance.
In this research, different loss models of the centrifugal compressor were reviewed and investigated. Then 1D codes were developed based on the loss models, and performance characteristics of S2B Schweitzer and GT4082 Garret compressors at different conditions were achieved. In order to evaluate the modeling results,... 

Axial compressors are utilized to increase compressible flow pressure in an efficient manner where mass flow rate is high, such as aviation engines and power generation gas turbines. The flow is compressed within this machine through several stages. Each stage consists of a rotor blade row followed by a stator blade row. Energy transfer to the air is performed on the rotor by changing its velocity vector. Then, pressure is recovered from velocity by diffusion, meanwhile turning the flow direction through stator blades. These blades have been designed and optimized with various methods evolved with developing computational and manufacturing facilities. In this thesis the aerodynamic design of... 

The purposes of this research are one and three dimensional aerodynamic designs of a twin entry radial-inflow gas turbine's impeller. The GT4082 model Garrett turbocharger was chosen for this purpose. In order to predict existing turbine performance curves one dimensional model was prepared for whole turbine. For validating the 1d-modeling's results, widespread tests were performed on the turbine at Sharif University of Technology turbocharger lab. Comparing the results of 1d-modeling with experimental results, show 4.7% and 4% max difference for efficiency and mass parameter respectively. The wheel designing procedure started from primary design based on the mean line assumption, in 1-d... 

Turbojet engines are used widely in the aviation industry due to very high specific thrust. The design and manufacture of turbojet components are complex procedures and needs high technology. In this M. S.c Thesis, the structur and function of a turbojet engine are described. then all stages of design,manufacture ,test and control of a small turbojet engine which is developed by use of a turbocharger are specified. the design and construction of combustion chamber, exhaust nozzle, lubrication system, thrust measurement system, data acquisition system, fuel and ignition system ,control system and etc are carried out at Sharif University of Technology gas turbine laboratory. The one... 

Diesel engines have widely used in past hundred years. During this time costly and extensive researches have been done to improve engine performance, which is going on. Important issues of these engines are higher specific power and efficiency and lower specific fuel consumption and pollutions formation. One of the best methods for engine performance improvement is matching a convenient turbocharger on engine. A turbocharger increases the engine air mass flow rate by increasing the inlet pressure and density. Due to increase of fresh air mass flow rate, fuel mass flow rate and power would increase. The aim of this research is to choose the convenient turbocharger for the OM355 naturally... 

In this research, it is aimed to convert a turbojet engine to a turboshaft by replacing the exhaust nozzle with a new designed power turbine stage. The design procedure is backed up with parametric studies to increase efficiency. At first a program is written for one dimensional modelling of the stage of axial turbine. By the way, the three dimensional modelling of the stage of axial turbine with Ansys-cfx business software is done. These methods are validated by modelling the gas generator turbine and comparison of their results with experimental results. Then the power turbine including the blades and the geometry of flow walls on shaft and casing are designed. The performance of power... 

The project aims to select the best Waste gate opening pressure for my Turbocharged gas engine is m355G. For this purpose GT-power software for modeling engine power is used. it is reduced to the 38/11 percent. After checking the model in several Waste gate opening pressure Turbocharged Gas engine performance is evaluated and the best Waste gate opening pressure is achieved. The results show that the engine brake specific fuel consumption by changing the opening pressure of 165 mm Hg to 255 mm Hg 4/03 percent and 14/19 percent of the engine power is increased. Also opening pressure of 265 mm Hg to 255 mm Hg engine brake specific fuel consumption 0/25 percent and 0/88 percent of the engine... 

Prediction of axial flow turbine’s performance with different operating conditions due to the high costs and lack of reliable empirical data is always under developing. In this type of turbine, fluid flow is three-dimensional, viscous and highly turbulent. Nowadays, although a relatively detailed picture of the flow field can be obtained by the computational and numerical tools, but using of appropriate loss models in one-dimensional modeling for the performance prediction as well as optimization of the turbine in initial design phases, is a common trend.
In the current study, aerodynamic losses in the axial flow turbine are investigated. Several loss models for the axial flow turbines... 

Improvement of axial flow compressor is usually goal of manufacturers of these equipments. Because basic role of it in gas turbine efficiency too many researchers have effort to know phenomenon and effect of them on axial flow compressor's revenue and optimization of them. In this project the aerodynamic of axial flow compressor studied and effect of important parameters such as diffusion factor coefficient, optimum incidence angel and Mach and Reynolds number determined from text and papers. Then obtained a model from experimental data to determine shock loss and extended algorithms to specify critical Mach number and chocking mass flow. With quotation Craig and Cox method we determined a... 

For several decades, turbocharging of internal combustion engines has been a wide spreading technology to increase the engine output power as much as possible. Turbocharger has two main components: compressor, and turbine. Therefore, increasing the efficiency of turbine and compressor has a major role in engine performance improvement. This has been a continuous research goal in 20th century. Considerable advances has been achieved until now. Turbocharger turbine should be matched to engine in a wide range operation conditions with high efficiency. Many researchers have published their achievements considering turbine elements design improvements. This research is focused on the turbine... 

Prediction techniques of axial flow turbine performance for different operating conditions are always developing due to high costs and lack of reliable empirical data. In axial gas turbines, fluid flow is three-dimensional, viscous, and highly turbulent. Nowadays, although flow field specifications are predicted accurately well using computational and numerical tools, the appropriate loss models are required for one-dimensional modeling and optimization in early design phases. In this research, an accurate and a complete investigation of aerodynamic losses in axial flow turbines will be discussed. Some suggested models for calculating losses in axial gas turbines, are considered and... 

The purpose of this research is providing the preliminary study and designing, fabricating and installing diffuser vanes on the vaneless diffuser compressor to improve its overall performance. To meet the goal, the GT4082 turbocharger centrifugal compressor is chosen as the basis unit. The compressor is fully modeled, to predict the compressor performance curves. One dimensional and three dimensional models are provided, to simulate the compressor with vaneless diffuser as well as vaned diffuser. In one dimensional model, governing equations are continuity, energy, and state and also the empirical components losses coefficients of the compressor are used. In this method, fluid properties are... 

The design and optimization of axial flow compressor is of great importance due to its various industrial applications. Due to the time-consuming and costly procedures of design, manufacturing, and performance tests of the compressor, it is necessary to evaluate and modify its performance with simple, inexpensive and reliable methods before manufacturing the final design. One of the available methods is the results of the linear cascade tests. In this study, in order to investigate this issue and consider its usefulness, an incompressible linear cascade test bed was designed and established based on the mean section profile of the rotor and stator of the axial compressor of Sharif University... 

Axial compressors play an important role in industry and aerial and land-based engines. Hence their design and optimization is of great importance. Due to the high costs associated with design and manufacturing of axial compressors, developing a sophisticated, rapid, low-cost and reliable methods for machine performance prediction is imperative. In this study, an attempt was made at introducing such a method. In this method, isolated airfoils were built in two different scales based on medium radius cross section of stator and rotor blades of the axial compressor of Sharif University of Technology gas turbine laboratory. Using the existing wind tunnel set-up at the aforementioned laboratory,... 

Improving compressor performance and arriving at better conditions has always been considered by researchers and industrialists. However axial compressor design process is time consuming, very costly, and involves uncertainties and iterations such that sometimes the preset targets are not achieved. Therefore it is required to be able to perform preliminary design and specify the compressor geometry and blade specifications and predict the performance characteristics with a fast, cheap method with required accuracy suitable for this step before detailed design and manufacture. Also some design methods need a primary geometry that is generated by these methods.In this work, towards achieving... 

The actual flow stream through compressor is 3D and fluctuated because of complicated geometry, fluid viscosity and high velocity. Therefore, more accurate analysis of this kind of flow, it is better to use 3D model. Nowadays the flow modeling software are able to model and analysis flow regime using numerical methods in three dimensions. Using these software allow us to find the ways which can reduce the energy losses to improve compressor efficiency.In current work, based on 3D numerical analysis, the flow regime in a centrifugal compressor is investigated and also the sensitivity of this analysis with mesh sizing is explored. The k-e type RNG model is used for modeling turbulent behavior... 

Increasing the power of a turbocharged diesel engine without changing main engine components is important in industrial applications, with economic benefits. The engine power can be increased by higher boost pressure. In this research, the turbocharged diesel engine performance improvement was investigated to increase the engine power. As a case study, the performance improvement of OM355A turbocharged diesel engine carried out. For this purpose, the engine was modeled in boost module of the AVL software. First, naturally aspirated OM355 and turbocharged OM355A diesel engines were modeled. Then the simulation results were evaluated in compare with engine tests data. Maximum difference in... 

Radial inflow gas turbines are widely used in auxiliary power units, small industrial gas turbines and turbocharger of internal combustion engines. They have advantage for low mass flow rate and wide range operation conditions. This research aimed to improve aerodynamic performance of the radial turbine of GT4082 Garret turbocharger. First, performance characteristics of the turbine were obtained experimentally at Turbocharger Laboratory of Sharif University of Technology. Laboratory results are the basis for modeling evaluation. Then, a one-dimensional model was developed to predict the turbine performance characteristics. The model results were compared with experimental results, that... 

The twin-entry radial inflow gas turbine is extensively used in engine turbochargers. The use of twin-entry radial flow turbine in the turbocharging systems makes it possible to use the kinetic energy of pulsating exhaust gases. This turbine is usually exposed to partial admission conditions in engine operating conditions, which the flows in each inlet are not equal for most of the time. This partial admission varies from zero flow in one entry with full admission in the other, to full flow in both entries. The flow pattern in this turbine is complex and three dimensional due to geometry and inlet conditions. Therefore, better understanding of the flow pattern and losses in the turbine can...