Sharif Digital Repository

In this paper, the performance of the twin-entry radial flow turbine under steady state and partial admission conditions is modeled. The method, which is developed here, is based on one-dimensional performance prediction. In one-dimensional modeling, the flow properties are assumed constant on a plane normal to the flow direction. This assumption is in contrast with the flow at the rotor entry of a twin-entry turbine under partial admission condition. In this study the one-dimensional performance prediction method for a single-entry turbine is modified to analyze the twin-entry turbine. In particular, the loss coefficients due to friction, clearance and blade loading, which are already... 

Iran is located at the high altitude region and has a diverse four season climate. The temperature difference of two locations at the same time reaches to 50° C. Therefore, the modern direct injection turbocharged engines are highly affected at this condition. This paper deals with the effects of temperature and pressure variations on the engine performance and fuel consumption of turbocharged gasoline direct injection engine. Ford ecoboost is selected for this study and the base experiments are performed at the sea level. At the next step, a comprehensive one-dimensional model of the engine is constructed in GT power and validated with experimental data. Validated model is implemented to... 

Iran is located at the high altitude region and has a diverse four season climate. The temperature difference of two locations at the same time reaches to 50° C. Therefore, the modern direct injection turbocharged engines are highly affected at this condition. This paper deals with the effects of temperature and pressure variations on the engine performance and fuel consumption of turbocharged gasoline direct injection engine. Ford ecoboost is selected for this study and the base experiments are performed at the sea level. At the next step, a comprehensive one-dimensional model of the engine is constructed in GT power and validated with experimental data. Validated model is implemented to... 

Performance characteristics of turbocharger turbine and compressor such as efficiency, mass parameter and power are determined experimentally at turbocharger laboratory. Accurate determination of the performance map is significant for manufacturers as well as end users. To this end accurate measurement of test parameters such as temperature, pressure, and speed are required. In this paper an analytic method to predict the measurement uncertainties in turbocharger laboratory, is described. Furthermore the effect of each test parameter on the performance uncertainty is considered. Test parameters that have the most significant influence on the performance uncertainties are identified.... 

In this research, effects of excess air ratio and waste gate opening pressure threshold on NOx emission and performance in a turbocharged CNG SI engine are studied experimentally at 13-mode ECE-R49 test cycle. The engine power, boost ratio and charge air temperature are investigated experimentally at the cycle for different waste gate pressure thresholds. A code is developed in MATLAB environment for predicting engine performance and NOx and the results are validated with the research experiments. The effects of excess air ratio on the engine indicated power and specific fuel consumption as well as NOx emission are numerically investigated at WOT by the code. NOx emission of WOT is max at... 

Turbocharging of gasoline engines has been improved less than diesel engines due to some difficulties, especially knock phenomena. They require wider air flow range and faster response too. A computer code is developed to simulate turbocharged gasoline engine behavior. A three zone combustion model is employed. Different performance curves at speed and equivalence ratio ranges are prepared. By this code naturally aspirated and turbocharged behavior are compared. A turbocharged aftercooled engine has been studied in various cases to complete the investigation. Some aftercooler effects are described experimentally. Modeling and experimental results are compared providing valuable achievements.... 

The performance parameter uncertainties of turbomachines at different rotational speed were determined by experimental and analytical consideration. The instruments/sensors were located and installed according to the standards for evaluating the performance characteristics of turbine and compressor in a turbocharger laboratory in a wide range of rotational speeds. The comparison of turbine and compressor sensitivity shows that the sensitivity of compressor to 1% shift in the pressure is higher than that for the turbine. Results also show that the sensitivities of efficiency and power of turbine reduce as rotational speed increases. The total uncertainty of turbine and compressor are obtained... 

This paper investigates the control of diesel engines comprising two actuators: exhaust gas recirculation (EGR) valve and variable geometry turbocharger (VGT) to mitigate the exhaust emissions. In contrast to conventional control techniques, multi-model predictive control (MMPC) algorithm is employed for control purposes. With the help of proposed scheme, constraints of the control problem is also considered and nonlinear model to enhance performance is utilized. In doing so, new controller tries to fulfill a compromise between fuel consumption and torque response by regulating air-to-fuel ratio and EGR fraction to decrease pollutants emission especially nitrogen oxides (NOx). The dynamic... 

In this research, aerodynamic design of a twin-entry radial-inflow turbine was done based on the direct method using a developed design code. The Garrett turbocharger was chosen for this purpose. At the first step, the 1D design, based on the impeller efficiency convergence, was performed. In 3D design, which is divided into preliminary and detail design, the profiles of the impeller and blade angle was carried out. Afterward the 3D shape of the blade can be achieved by combining these profiles. There is a good geometrical agreement between designed impeller and the laboratory’s existing impeller in both steps. In order to predict the performance of the turbine, the 1D analysis code was... 

In this paper the performance characteristics of turbocharger twin-entry radial inflow gas turbine with unsymmetrical volute and rotor tip diameter of 73.6 mm in steady state and under full and partial admission conditions are investigated. The employed method is based on one dimensional performance prediction which is developed for partial admission conditions. Furthermore this method is developed for unsymmetrical volute of the turbine considering flow specifications. Experimental investigation of the research carried out on special test facility under full and partial admission conditions for a wide range of speed. The comparison of experimental and modeling results shows good agreements.... 

In this paper, the performance of the twin-entry radial flow turbine under steady state and partial admission conditions is modeled. The method, which is developed here, is based on one-dimensional performance prediction. In one-dimensional modeling, the flow properties are assumed constant on a plane normal to the flow direction. This assumption is in contrast with the flow at the rotor entry of a twin-entry turbine under partial admission condition. In this study the one-dimensional performance prediction method for single-entry turbine is modified to analyze the twin-entry turbine. In particular, the loss coefficients due to friction, clearance and blade loading, which are already...