Sharif Digital Repository

The objective of the current work is to investigate the application of tandem blade rotor for possible improvements of a transonic fan. A near term application of tandem blade rotor could be either in the last stages of a high pressure compressor or in the fan section. The present research is motivated by evaluating the tandem configuration for transonic fan of high bypass ratio turbofan engines. The main idea is to achieve higher overall blade loading and at the same time lowering the flow separation tendency by shifting the boundary layer growth to the rear rotor. A computational fluid dynamics code, solving the Navier-Stokes equations based on a flexible multiple-block grid discretization... 

Axial compression systems are widely used in many aerodynamic applications. However, the operability of such systems is limited at low mass flow rates by fluid dynamic instabilities. These instabilities lead the compressor to rotating stall or surge. In some instances, a combination of rotating stall and surge, called modified surge, has also been observed. In this research Moore – Greitzer model that the principle of constant speed mode checks as a base case has been considered and the developed condition of this model in which the dynamic model of the shaft will also respect and shaft rotational speed as a basis for state shall consider, has been analyzed.
In this study the effect of... 

Axial-flow compressor is one of the most basic components of gas turbine engines. Consequently, it is essential to design this machine appropriately. Full three dimensional analyses of axial-flow compressors is time consuming due to the flow field complexity, so a method with minimum running time and producing an acceptable design is required. One dimensional design method is a low cost procedure with acceptable results for preliminary stages of design. It receives inlet flow conditions, such as total pressure ratio, mass flow and rotational speed and designs a compressor which satisfies the desired input data. Too many efforts have been accomplished to predict energy losses, design... 

Overall performance improvement of gas turbine is available by modifying each component of cycle. The purpose of this research is to improve performance of a micro turbine with 200 KW power, by redesigning compressor set. Considerable increase in performance and stability occurs, by adding individual stage of axial compressor at the entry of centrifugal section. It should be noted that, this improvement occurs without a significant increase in size and without having to change the centrifugal compressor design.In this study, design of one stage axial compressor and three dimensional modeling is discussed after, modeling and preliminary design of centrifugal compressor. Then, after obtaining... 

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... 

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... 

With everyday increasing application of gas turbine in different industries, fast and accurate tools for design, analysis and performance estimation of gas turbines have found many proponent; Compressors, as one of the most important parts of gas turbines, are no exception to this ordinance. Although development of Computational Fluid Dynamics (CFD) method was a great aid to improve the accuracy of this tools, complexity and being time consume make them uncommon and unpopular during preliminary design and analysis process. So it could be imply that simple analysis methods, such as 1D, 2D and quasi-3D, are not only not abandoned, but also very practical and most applied in preliminary design,... 

Streamline Curvature method is one of the most commonly used methods by industry for prediction of axial flow compressors. This method analyze axial compressor by solving radial equations in the meridional plane to locate streamlines and also by using empirical models to predict total pressure loss. Despite growth of CFD models, Streamline Curvature method has been considered as most practical method for compressor preliminary design and performance assessment because of it’s high speed and good precision. In the current work a C++ code (SLC) has been developed using streamline curvature for axial flow compressor performance analysis. This code receives compressor geometry, properties of...