نوع مقاله : مقاله پژوهشی
نویسندگان
1 عضو هیات علمی / پژوهشگاه هوافضا، وزارت علوم، تحقیقات و فناوری
2 دانشجوی کارشناس ارشد مهندسی هوافضا / پژوهشگاه هوافضا، وزارت علوم، تحقیقات و فناوری
3 عضو هیات علمی / دانشکدة مهندسی هوافضا، پژوهشگاه هوافضا، وزارت علوم، تحقیقات و فناوری
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Performance of a aerospace vehicle or spacecraft during the re-entry have great dependency to flow-field physics around it. Aerothermodynamics heating in high velocity is highly dependent on geometry and flow-field physics. It is a big challenge of these vehicles for re-entry phase and engineers for reduction of these inappropriate effects use thermal protection systems with much expensive prices. In this Concern, the effects of flow control using counter flow axial jet ahead of a 2.6% scale model of Apollo capsule are investigated in order to decreasing the undesirable effects of aerothermodynamics heating. The aerodynamics performance of this capsule has been studied at free stream Mach number of 3.48 with 5 different flow rates of counter flow jet. The results show that two flow regimes can be seen by increasing the jet mass flow rate; Long Penetration Mode (LPM) and Short Penetration Mode (SPM). LPM that appears in low mass flow rates causes the increment of the shock-detachment distance, unsteadiness and flow oscillations and SPM that appears in high mass flow rates causes the decrement of the shock-detachment distance. Transition of LPM to SPM occurs in mass flow rate between 0.0145kg/s and 0.113kg/s. The results indicate that the counter flow jet decreases the drag about 80%. Moreover, the effects of excitation in counter flow pulsed jets at 1000Hz and 2000Hz frequency have been investigation for decrement of mass of fluid injection in this study. The results of this investigation shows that increment of excitation frequency to 2000Hz reduces drag near to 60%.