Aerospace Science and Technology
Gholamhosein Pouryoussefi; Sara Javanmard; MohamadAli Heidari
Abstract
In this study, the performance of a cold atmospheric pressure plasma jet using neutral helium gas was experimentally investigated. Cold atmospheric pressure helium plasma jets have gained popularity in various processing applications due to their stability and enhanced reaction chemistry. The researchers ...
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In this study, the performance of a cold atmospheric pressure plasma jet using neutral helium gas was experimentally investigated. Cold atmospheric pressure helium plasma jets have gained popularity in various processing applications due to their stability and enhanced reaction chemistry. The researchers examined the effect of applied voltage, flow rate, and electrode configurations on the length of the helium plume and analyzed the physical parameters of the plasma plume, including discharge voltage and average gas and discharge gap temperatures. The study revealed the presence of three operational modes: plasma bullets, a chaotic mode, and a continuous mode. Initially, the plasma jet operated in a deterministic chaotic mode after breakdown. Transitioning to the turbulent mode, increasing the gas flow rate resulted in a decrease in the plasma jet length. The flow rate required for laminar-to-turbulent transition increased with the applied voltage. By increasing the electrode separation and flow rate, the continuous mode was observed, where excited species remained within the inter-electrode space throughout the voltage cycle. Additionally, it was observed that the temperature of the discharge gap was close to room temperature. These findings provide valuable insights into plasma jet formation mechanisms and highlight the potential of tailoring plasma jet modes for specific processing applications.
Aerospace Science and Technology
Sam Mohamad Hassan Pouryoussefi; Sohrab Gholamhosein Pouryoussefi
Abstract
Importance of study of pulsating heat pipes (PHPs) behavior and limitations in conducting experimental studies, the necessity of numerical simulations is getting critical in this area. In present work, numerical simulations are carried out for pulsating heat pipes. Thermal performance of closed loop ...
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Importance of study of pulsating heat pipes (PHPs) behavior and limitations in conducting experimental studies, the necessity of numerical simulations is getting critical in this area. In present work, numerical simulations are carried out for pulsating heat pipes. Thermal performance of closed loop pulsating heat pipes is investigated at different operating conditions such as evaporator heating power and filling ratio. Water, ethanol, methanol and acetone are employed as working fluids. A two-dimensional single loop PHP is used for present study. Computational Fluid Dynamics (CFD) video technique is employed for flow visualization purpose. Perfect match was observed between the present CFD video clip and previous experimental video-based studies in terms of flow pattern and behavior. Present study shows how researchers can benefit from developments of numerical tools to test pulsating heat pipes behavior at different operating conditions or different working fluids without facing difficulties and limitations of applying laboratory thermal measurement equipment or high-speed cameras. The CFD video clip as result of numerical simulation was found very informative for flow visualization purpose. The simulated clip made it much easier to capture phenomena occur in a pulsating heat pipe. The thermal performance investigation at different operating conditions and working fluids was found very informative in terms of application and design purposes especially for experimental studies. By increasing heating power greater than 60 W, circulation velocity was increased for most cases. Phase contour videos are inserted at the bottom of the article.
Aerospace Science and Technology
Ali Khoshnejad; Reza Ebrahimi; Golamhosein Pouryossefi
Abstract
Aero-engine entrance conditions are not always ideal and, for various reasons, inlet distortion may occur and cause inlet blockage and reduction of compressor performance. The aim of this study was to numerically simulate the effects of plasma actuators on the enhancement of low-speed axial compressor ...
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Aero-engine entrance conditions are not always ideal and, for various reasons, inlet distortion may occur and cause inlet blockage and reduction of compressor performance. The aim of this study was to numerically simulate the effects of plasma actuators on the enhancement of low-speed axial compressor rotor performance under radial inlet distortion. First, compressor performance under radial inlet distortion with 15% and 20% blockage and theirs destructive effects on stall margin was investigated. Then, the effect of plasma actuators on rotor loss subjected to inlet distortion was investigated, using an algebraic model based on the plasma actuators physics in form of body force distribution in Naiver-Stokes equations. The results show that radial inlet distortion causes decreasing stall margin of the compressor. In addition, according to the findings, applying plasma actuators boosts the flow momentum behind the distortion screen and reduces the blockage of the rotor tip region, leading to decreasing losses. Furthermore, at 15% blockage, the plasma actuators caused to increase the stall margin from -11% to -5% versus the rotor in clean condition.
