Behnam Ghalamchi

Lappeenranta – Lahti University of Technology LUT · Department of Energy

This paper presents both experimental and numerical study on the dropdown of a generator rotor in a two-stage radial gas turbine utilizing AMB system. The simulation unifies the FE-model of the flexible rotor and the dynamic model of backup bearings. The system under investigation includes a flexible rotor, an axial and two radial AMBs and two back...

In this paper, the functionality of a swashplate mechanism coupled with a series of one-way overrunning clutches is studied. The novel mechanism is constructed by coupling a swashplate and one-way overrunning clutch with other mechanical components to allow producing a continuously varying gear ratio. To access the capability of the proposed mechan...

The main objective of this paper is to study the importance of rotor assembly procedure on balancing behavior of a high-speed rotor. The rotor consists of series of magnets in the electric motor section is considered as a case study. This study employs 3D beam elements based on the Timoshenko beam theory to model the model the dynamic behavior of t...

This paper presents a simulation method that is used to study subcritical vibrations of a tube roll in a paper machine. This study employs asymmetric 3D beam elements based on the Timoshenko beam theory. An asymmetric beam model accounts for varying stiffness and mass distributions. Additionally, a detailed rolling element bearing model defines the...

The avoidance of chatter is an important issue in metal cutting. Due to variation in material quality, clamping, and wear in machine tool or tool insert the process conditions may change. A work piece that has been of sufficient quality earlier in the run can no longer be cut to fulfill the requirements for surface integrity, topography and part ge...

Cooling is a significant part of any power generation cycle. An Air Cooled Condenser (ACC) is used to condense steam vapors from the steam turbine, lower heat rejection temperature and increase the power generation efficiency. An ACC works in a closed loop with the power turbine and its performance is directly linked to the power output of the powe...

Decentralized power and heat generation is a growing trend throughout the world. In smaller applications, electrical power output less than few megawatts, reciprocating engines have dominated the market. In recent years, small sized gas turbines have emerged as challengers for the reciprocating engines. The small gas turbines have a growing share o...

Since spherical roller bearings can carry high load in both axial and radial direction, they are increasingly used in industrial machineries and it is becoming important to understand the dynamic behavior of SRBs, especially when they are affected by internal imperfections. This paper introduces a dynamic model for an SRB that includes an inner and...

The main scope of this paper is optimization of high speed rotor systems by using Evolutionary Algorithm. The target of the optimization is finding geometrical parameters of the shaft, in such a way that the critical speeds are not occurring in the operation speed range. Rotating machines have a wide range of applications in industrial machinery an...

Since Spherical Roller Bearings (SRBs) have high load capacity and are self-aligning, they are seeing increasing use in the rotating machinery. Typical applications are paper machines, steel rolling, marine equipment, geared transmissions and modern high power wind turbines. Therefore, it is becoming increasingly important to study the dynamic beha...

Imperfections in a rotor-bearing system may cause undesirable subcritical resonances occurring when the rotating speed of the rotor is a fraction of the natural frequency of the system. These resonances arise partly from rotor imperfections and partly from bearing imperfections. This study demonstrates that the subcritical twice-running-speed vibra...

Rolling element bearings are essential components of rotating machinery. The spherical roller bearing (SRB) is one variant witnessing increasing use because it is self-aligning and can support high loads. It is becoming increasingly important to understand how the SRB responds dynamically under a variety of conditions. This study introduces a compu...

Rolling element bearings are essential machine elements in the rotating machinery. Extensive research has been conducted to study the dynamics of ball bearings, while studies related to spherical roller bearings are short-shrifted. On the other hand, the number of industrial applications that utilize spherical roller bearings has been increasing co...

A new generation for an omni-directional ball wheel mobile robot with unique driving mechanism is introduced. This driving system overcomes to problems arise using traditional omni-wheels such as, vibration, inappropriate to employ in outdoor applications and limited load capacity. Mechanical structure of this robot has several distinctive characte...