Sharif Digital Repository

In this project Sharif Gas Turbine laboratory turbojet engine, and the turboshaft engine which is designed based on the turbojet gas generator are statically and dynamically modeled and required functions for turboshaft control are extracted. In static modeling a repetitive process is applied to reach static operation points. Static operation line and static characteristics of turbojet engine are extracted and compared to relevant sources. In dynamic modeling of turbojet engine a lumped volume is allocated to each component of engine and gas dynamic equations are solved in this volume along with individual performance map of engine components to acquire output characteristics in each time... 

In gas turbine industry, usually turboshaft engines are designed base on turbojet and turbofan gas generators. Hence, the overall cost of product design and manufacturing will decrease and sales and revenues will increase. It is also common to convert aerial engines with their flight life passed to industrial engines. In the present work, the conversion of an existing turbojet in the gas turbine lab of sharif university of technology to a turboshaft has been investigated. In the first step of project, the experimental data of turbojet performance are considered and the design point of the turboshaft engine will be determined. Then, nominal rotational speed of power turbine and zero to three... 

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... 

In this thesis, our aim is to simulate steady and transient operation of a turboshaft engine with a free power turbine. For better understanding of physics of the problem, nested loops method is used in order to simulate the steady state operation. Furthermore, methods based on steady operation are used in simulating transient behavior of the engine. Scaling methods are used to extract performance characteristics of the engine components. It is assumed that performance characteristics have similar behavior in high engine shaft speeds. Bearing this in mind, validity of our simulations are confined to such high shaft speed conditions. In addition, for off design analyzes it is assumed that... 

Auxiliary Power Unit (APU) is a single spool turboshaft engine aimed to start the main gas turbine engine on the ground as well as to supply the necessary power to the auxiliary and electrical equipment during an engine emergency shut down. Similar to the main gas turbine engine, the performance of APU depends on the altitude. Hence, a control system with an appropriate logic is required for a dual function APU which provides electrical power as well as pressurized air through a generator and load compressor, respectively. It should be emphasized that while the output of the generator remains almost not affected with the altitude, the performance of the load compressor is altered by this.... 

The purpose of this study is developing the design means of a high pressure centrifugal compressor impeller for aviational applications i.e. turboshaft engines. The logic and constraints of designing a high pressure centrifugal impeller for a turboshaft engine is different from those of low pressure aerial or high speed industrial ones. This kind of impeller is deployed in a number of advanced generation of aero engines. In this study, the centrifugal impeller design tools are developed using two design methods. Then, the results are compared, validated and corrected with an existing high pressure impeller data. A number of impellers with pressure ratios ranging from 6 to 11 are designed and...