Sharif Digital Repository

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... 

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... 

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... 

Nowadays, fuel optimum used in engines is an important matter. To achieve this aim, we need to tune engine. The big companies have paid attention to these cases. Because of it, there are strict standard in the world and in other side the internal combustion engine is very common.
In the internal combustion engine after cylinder, the gas inter to an encasement which is called exhaust manifold. In the other hand, exhaust manifold is in upstairs of turbine and waste-gate in turbocharged SI engines. To control fuel used and descries the amount of emissions, exhaust manifold pressure is very important. In the other hand, monitoring of exhaust manifold pressure can use for fault detection of... 

Nowadays internal combustion engines play an important role in the power generation as well as transportation fields all over the world. By using the turbocharger in internal combustion engine, more power is obtained in compare with aspirated engine having the same size, which is limited for gasoline engines. In this research, by a three-zone computer simulation code and experimental tests, the power boost limitations of the gasoline turbocharged engine are investigated. The results of single cylinder aspirated gasoline engine tests are used for validation the natural aspirated part of the code. For validating the turbocharged engine simulation, the results of a four cylinders gasoline... 

Proper operation of a spark ignition engine is required by comfort demands of a vehicle driver and governmental legislations. Therefore it is essential to monitor, within an online technique, the engine and detect any fault which disrupts its operation. The gas exchange path (including the intake and exhaust subsystems) is an important part of turbocharged engines responsible for accurate control of both engine power and emissions. Monitoring the path for fault detection and isolation (FDI) has been always demanded due to many failures it may face since the turbocharger exasperates the harsh working conditions for components involved in the path. This paper presents a novel model-based... 

This research is done as a continuation of previous efforts to develop a turbojet engine from a turbocharger at departments of mechanical and aerospace engineering of Sharif University of Technology and describes the necessary steps in order to design and build a dual fuel combustion chamber for a small, turbocharger based turbojet engine. At first, zero-dimensional analysis is done using a code written in Matlab. Using this code, matching of the compressor and turbine in the turbojet thermodynamic cycle is verified and the operating line of the turbojet engine has been extracted. Henceforth, operating conditions of the combustion chamber to start design process is determined. In designing... 

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... 

Today, spark ignition internal combustion engines make up a large percentage of passenger car engines, so their performance improvement is important. Turbocharging of these engines, although is an appropriate method to enhance their specific power and improve their specific fuel consumption, but it has big problems such as the possibility of knock and increasing the NOx emissions in the engine. In this study, resolving these problems is intended by controlling the engine inlet charged air temperature to improve performance of the engine. For this purpose, the investigations are conducted experimentally as well as numerically. The experimental studies are carried out on a turbocharged... 

Thermodynamic analysis of a system is a method for recognizing the type of energy transmission between system and surrounding environment. It also helps to find how macroscopic properties of the system change during this process. This analysis is based on first and second laws of thermodynamic. The first law expresses conservation of energy and inspects quantity of energy transmission but doesn’t evaluate quality of energy. The second law expresses quality of energy and the ability of doing work. The analysis that uses both of the laws is named exergy analysis. By exergy analysis the place of useful energy losses in the system can be determined. In this research the exergy analysis of... 

Combustion and NOx emissions were simulated by quasi-dimensional and ratereaction methods respectively in a turbocharged CNG engine. Mean-value turbulence modeling was carried out during compression and combustion processes to simulate combustion process better. The most appropriate NG flame speed for the CNG turbocharged engine was applied and ignition delay was ended when flame radius became more than turbulence integral length scale. Hemispherical flame propagated from spark gap center and its intersection with reciprocating Mexican-hat piston bowl was calculated analytically. Thermal boundary layer, as a novel approach, was considered in the simulation and a better agreement of predicted... 

Duo to the strictly pollution legislation in the last decade and increasing demand of lightweight internal combustion engines with rated power , turbocharging of the spark ignition engines become more interested. Therefore the turbocharging of M15GS engine was studied in both gasoline and natural gas fuels with purpose of enhancement of performance characteristic of engine. According to this approach 0-D turbocharger matching performed for gasoline and natural gas fueled M15GS engine. Also an innovative 1-D turbocharger matching performed for gasoline fueled engine. Then engine equipped with SJ50 turbocharger and dynamometer and combustion development tests performed on gasoline fueled... 

Since the construction of the first models of internal combustion engines in the nineteenth century, efficiency and, since the late twentieth century, pollution and fuel consumption has been the main issue for researchers and manufacturers who have always sought to improve it. Manufacturers of internal combustion engines are required to perform numerous tests to carefully study and increase the level of technology and reliability of their products. There have been two ways for them to do this; the first way is to use the experimental method; that is, making multiple samples that require a high cost that makes it impossible. The second way is to use engine simulation software, which can be... 

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... 

With the global population increase, the fossil fuel consumption rate is rising. Issues of energy aspects and environment pollution have received more attention than before. In this regard, internal combustion engines play an essential role. By improving the performance these, it is possible to reduce their specific fuel consumption. Also, with the development of various industries, their required power is increasing, and providing a new engine with higher power and better performance needs high investment. While, providing this requirement by improving the performance of the existing engine costs much less. Considering that internal combustion engines, especially diesel engines, are used in... 

The Rotary Combustion Engines are known as Wankel Engines, for the first time designed and built by German inventor, Felix Wankel. In open letrecher, research reports about these engines are much less than piston engines. While, the wankel engine hase many advantages such as lower volume, less weight, less vibration and use of fuels lower octane number in compared with reciprocating engines. Therefore, it has particular importance in industries such as aircraft manufactueres.In this theses after the introduction chapter, Wankel engines and Turbochargers usage are reviewed. Then the Wankel engine and its turbocharging are searched in letrecher. Then, a computer code for simulation the Wankel... 

The internal combustion engine power is determined by the amount of fuel effectively burned inside the engine cylinders. On the other hand, the fuel consumption is proportional to the air mass that enters the cylinders in each cycle. Conventionally, incoming the engine inlet air is at ambient conditions. However, with higher air density, the engine power increases for the same dimensions, so-called turbocharging. Although the engine's structure remains unchanged, it may be necessary to adjust the main systems of the engine simultaneously. This research investigated maximizing the power of a turbocharged diesel engine based on upgrading the degree of turbocharging. For this purpose, the EM355...