Sohayla Abdolahi; Fskhri Etemadi; Mohammad Ebrahimi
Volume 8, Issue 3 , October 2015, , Pages 41-53
Abstract
In this study, the aerodynamic heating of the flying body during powered flight phase has been numerically investigated. The conjugate simulation of fluid heat transfer and solid heat conduction has been considered. To this aim, the coupling boundary condition has been used for body shell that allows ...
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In this study, the aerodynamic heating of the flying body during powered flight phase has been numerically investigated. The conjugate simulation of fluid heat transfer and solid heat conduction has been considered. To this aim, the coupling boundary condition has been used for body shell that allows the conjugate heat transfer investigation in the fluid and solid domains simultaneously. The model has been considered as a circular cylinder and spherically blunted cone nose with 350mm in diameter. The investigation has been carried out at different Mach number from 1.5 to 4.2 to cover range of supersonic flow. The advantage of this method is that the wall temperature and heat flux ââin any part of the nose and body shell with or without axial symmetry, connected components and other protuberances could be calculated at different angles of attack. Finally, the approach has been validated through the results of analytical and numerical methods for aerodynamic heating of axisymmetric vehicles.
Mohammad Tahaye Abadi; Mehdi AlizadehYazdi; Mohammad Ali Farsi; Mohammad Ebrahimi
Volume 7, Issue 4 , January 2015, , Pages 51-62
Abstract
The paper concerns with the experimental analysis of the pyroshock wave propagation in the structure of Kavoshgar's payloadon the ground. The source of waves is the explosion of pyrotechnic materialacting as the actuator of separation mechanism for the payload subsystems. The shock sensors are attached ...
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The paper concerns with the experimental analysis of the pyroshock wave propagation in the structure of Kavoshgar's payloadon the ground. The source of waves is the explosion of pyrotechnic materialacting as the actuator of separation mechanism for the payload subsystems. The shock sensors are attached in different locations of structure to measure the acceleration amplitude along three orthogonal directions after the activation of pyrotechnic material.The experimental setup is used for measurement of the acceleration history as well as the evaluation of the shock response spectrum at specific locations during two-stage separation of payload subsystems. The experimental acceleration record is evaluated to eliminate the noise signals and incorrect data. The variations of shock  response at different payload locations are evaluated to determine the amplitude attenuation of the wave passing through the structure body and joints. The measured data are also employed to determine the working condition and design criteria for the equipment of Kavoshgar payload.
F. RasiMarzabadi; R. Meshkani; H. Pouryavi; M. A. Farsi; M. Ebrahimi
Volume 7, Issue 2 , July 2014, , Pages 23-33
Abstract
According to the importance of knowing aerodynamic parameters of parachutes used as recovery system of a sounding rocket, some launching tests were conducted to achieve the acceptable reliability. A testing rocket which simulated the recovery condition of the sounding rocket was used in these tests. ...
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According to the importance of knowing aerodynamic parameters of parachutes used as recovery system of a sounding rocket, some launching tests were conducted to achieve the acceptable reliability. A testing rocket which simulated the recovery condition of the sounding rocket was used in these tests. Furthermore, the results of the tests used for validating a simulation code written for investigating the aforementioned two stage recovery system process. Some aerodynamic parameters of parachutes such as drag coefficient, opening force coefficient, and filling time, filling distance and drag area increase during inflation process were estimated from the tests in various conditions. The results show that for the first and second used drogue chutes with large canopy-loading, in contrast to the main parachute with small canopy-loading, the inflation parameters were not dependent on the height or air density. The drag area versus time shows linear variation for the first drogue chute, and shows second and third function for the other two parachutes. The situation of the second drogue chute in front of the main parachute affects the filling time of the main parachute. The distance between the parachutes, the ratio of their canopy areas and the air velocity are some parameters that affect the filling time. The results of this investigation could be worth for the design of a decelerator system, preciously.
Z. Hajebrahimi; L. Alidoust; M. Arabian; E. Alavi; M. Ebrahimi; M. Bahrami
Volume 6, Issue 4 , January 2014, , Pages 37-42
Abstract
Stress environment of space flights including hypergravity and microgravity effect cell functions and processes. We studied effect of hypergravity and flight stress on function, death, growth and cellular damage of five cell lines including human vascular endothelial cells, rat bone marrow stromal cells, ...
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Stress environment of space flights including hypergravity and microgravity effect cell functions and processes. We studied effect of hypergravity and flight stress on function, death, growth and cellular damage of five cell lines including human vascular endothelial cells, rat bone marrow stromal cells, mouse embryonic fibroblast cells, PC12 cells and pancreas islands in Biological payload of 3th sounding rocket by NO, LDH, MTT and insulin assay kits. Our results indicated that effect of hypergravity increase significantly cellular death and NO secretion but we found no changes in insulin secretion and pancreas function.
E. Amani; M. Ebrahimi; J. Roshanian
Volume 3, Issue 2 , January 2011, , Pages 59-67
Abstract
در این مقاله، معادلات کوپلشده جسم صلب- تلاطم سیال- الاستیسیته برای پرواز شش درجه آزادی ماهوارهبرها توسعه داده شده است. معادلات حرکت به کمک معادلات لاگرانژ در دستگاه ...
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در این مقاله، معادلات کوپلشده جسم صلب- تلاطم سیال- الاستیسیته برای پرواز شش درجه آزادی ماهوارهبرها توسعه داده شده است. معادلات حرکت به کمک معادلات لاگرانژ در دستگاه شبه مختصات و همچنین در دستگاه مختصات اینرسی استخراج شدهاند. مدل پاندول ساده برای حرکت صفحهای به منظور مدل کردن دینامیک تلاطم سیال در پرواز شش درجه آزادی گسترش داده شده و تغییر شکلهای الاستیک بر اساس مختصات مودال نسبت به مختصات میانی ارائه شدند و نیز نشان داده شده است که این مدل با مدل سادهتر حرکت صفحهای که در مطالعات پیشین توسعه یافته است، سازگاری دارد. مدل دینامیکی پیشنهاد شده در کنار مدلهای لازم برای سایر زیرسیستمها در برنامة متلب/ سیمولینک با موفقیت برای شبیهسازی حرکت شش درجه آزادی ماهوارهبرها به کار گرفته شده است.
