Showing 3 results for Nosratolahi
Navid Farrokhi, Jamasb Pirkandi, Mehran Nosratolahi,
Volume 16, Issue 10 (1-2017)
Abstract
In the current study a combined heat and power (CHP) system based on diesel engines is studied. A CHP system is investigated parametrically according to first and second laws of thermodynamics. In this investigation instead of modeling the air standard cycle, the fuel air standard cycle and fuel combustion are simulated, which leads to more accurate results. Since a standard cycle has many differences with an actual cycle, the exhaust gas from combustion chamber of a diesel engine is also used to simulate the CHP system, and the heat exchanger of the CHP is investigated from exergetic and economic viewpoints. It was seen that applying the pre-described system, it is possible to warm up 0.17Kg/s water from 25°C to 68.64°C. This enhances the overall efficiency of the system about 20%, raising it up to 80%. Exergy destruction in heat exchanger is almost high which is due to heat transfer process and high temperature difference in the heat exchanger.
Mehran Nosratolahi, Mohammad Adib Ghapanvary,
Volume 17, Issue 4 (6-2017)
Abstract
In this paper conceptual design and optimization of gliding parachute configuration are discussed. To this end, a design cycle is planned for conceptual design procedure and an optimization-based design approach are established to provide an integrated design algorithm for gliding parachute platforms. The optimization problem is formulated with a cost minimization approach which is constrained by static stability and safe landing velocity as design criteria. The parachute configuration is defined with minimum required parameters and aerodynamics, stability and performance characteristics are provided based on a semi-analytical approach. Hence, a computational software is incorporated with theoretical approximations to provide the required disciplinary data flow in the design cycle.The significant design parameters are verified by available wind tunnel test data.Optimization problem is solved using genetic algorithm method whereas constraints are handled by penalty function approach.Trim points are obtained like an all-at-once approach through a simultaneous analysis and design algorithm. Finally, as a case study,optimized configuration is achieved for a real gliding parachute. Results show a fair estimation of parachute characteristics along with the reduction in manufacturing cost for new configuration up to 25%.
Mehran Nosratolahi, Ahmad Soleymani, Hosein Sadati,
Volume 18, Issue 1 (3-2018)
Abstract
The purpose of this paper is to design a control systwm with a pre-designed algorithm in order to reach a compromise between satellite attitude and thermal control systems. In addition to the indispensable attitude control system, a thermal control system (TCS) is regarded as a substantial subsystem in any given satellite. The latter is commonly used to effectively reduce the internal heat and/or the thermal tensions caused by solar radiations. In this paper, a novel actuators known as fluid momentum controllers (FMCs) have been utilized to simultaneously produce control torques and develop a cooling mechanism by circulating liquid through a ring. In this research, it has been assumed that the satellite’s internal temperature has reached a critical level to the extent that the FMCs are not able to reduce this temperature sufficiently. In such a case, it is possible to mitigate this problem using a combination of both attitude and thermal control subsystems (CATCS). To accomplish this, a thermal model has been employed to yield the temperature of all six sides of the satellite at each time step and a switching algorithm to design an integrated system. This algorithm uses a particular decision making logic to realize the reconciliation of the two subsystems. Also, a sliding mode controller has been used for the three axis stabilization of the satellite. Simulation results of the integrated attitude and thermal control system indicate that it is possible to conduct an appropriate temperature control while saving power and integrating the two subsystems.