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1
Zhang, Lin, Junli Yang, Tiecheng Duan, Jie Wang, Xiuyi Li i Kunyuan Zhang. "Numerical and Experimental Investigation on Nosebleed Air Jet Control for Hypersonic Vehicle". Aerospace 10, nr 6 (9.06.2023): 552. http://dx.doi.org/10.3390/aerospace10060552.
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A new idea of nosebleed air jets with strong coupled internal and external flow is put forward using the lateral jet control principle to improve the maneuverability and fast reaction capabilities of hypersonic vehicles. The hypersonic vehicle’s nose stagnant high-pressure and high-temperature gas is utilized as the drive source for long-term jet control. The significant coupled jet interaction of the internal and external flow changes the aerodynamic characteristics. As a result, the structure is basic and does not rely on any external source to achieve flight attitude control. The complicated flow characteristics of the nosebleed jet in supersonic crossflow surrounding the vehicle were numerically and experimentally investigated. The jet interaction characteristics and the aerodynamic characteristic changes generated by the nosebleed air jet are verified by comparing the flow field with and without the jet. Results indicate that the nosebleed air jet alters the center-of-pressure coefficient, which is subsequently coupled with the interference aerodynamic force. This results in a variation in pitch moment. The jet decreases the pitching moment coefficient when compared with the case without a jet. It is probable that combining nosebleed air jets with model centroid adjustment yields an optimal trim angle of attack.
2
Sabak, Ryszard. "Synthetic Diagnostics Of The JET System Of The JET-2 Unmanned Drone". Journal of KONBiN 32, nr 1 (1.12.2014): 37–44. http://dx.doi.org/10.2478/jok-2014-0029.
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Abstract In recent years, , newer and newer designs of unmanned air vehicles have been appeared and in a spread and spread area. That is why, their service and in particular their diagnostics should be carried out both before and in each flight. In this paper, a description of both unmanned air vehicle JET-2 and its units and control system are presented. The paper includes also description of signals which are transmitted in a real time from the dron to the flight control station. These signals enable to state whether the vehicle works in a correct way. An interactive diagnostics model is presented as two united equations of state which are based on an observation that the usable value of the UAV resulting from its working standards, depends on its technical condition and what is more, technical condition depends on its working condition (intensity of usage). It should be stated that technical conditions are an environment for working conditions and working conditions are an environments for technical conditions. Presented model gives a comprehensive information about technical and working capability of a vehicle. It enables to plan next flights taking into account their currant potential and capability.
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Park, Byoungjik, Yangkyun Kim, Jin Ouk Park i Ohk Kun Lim. "Jet Flame Risk Analysis for Safe Response to Hydrogen Vehicle Accidents". Sustainability 15, nr 13 (21.06.2023): 9884. http://dx.doi.org/10.3390/su15139884.
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With an increase in the use of eco-friendly vehicles such as hybrid, electric, and hydrogen vehicles in response to the global climate crisis, accidents related to these vehicles have also increased. Numerical analysis was performed to optimize the safety of first responders responding to hydrogen vehicle accidents wherein hydrogen jet flames occur. The influence range of the jet flame generated through a 1.8-mm-diameter nozzle was analyzed based on five discharge angles (90, 75, 60, 45, and 30°) between the road surface and the downward vertical. As the discharge angle decreases toward the road surface, the risk area that could cause damage moves from the center of the vehicle to the rear; at a discharge angle of 90°, the range above 9.5 kW/m2 was 1.59 m and 4.09 m to the front and rear of the vehicle, respectively. However, at a discharge angle of 30°, it was not generated at the front but was 10.39 m to the rear. In response to a hydrogen vehicle accident, first responders should perform rescue activities approaching from a diagonal direction to the vehicle front to minimize injury risk. This study can be used in future hydrogen vehicle design to develop the response strategy of the first responders.
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Whittlesey, Robert W., i John O. Dabiri. "Optimal vortex formation in a self-propelled vehicle". Journal of Fluid Mechanics 737 (15.11.2013): 78–104. http://dx.doi.org/10.1017/jfm.2013.560.
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AbstractPrevious studies have shown that the formation of coherent vortex rings in the near-wake of a self-propelled vehicle can increase propulsive efficiency compared with a steady jet wake. The present study utilizes a self-propelled vehicle to explore the dependence of propulsive efficiency on the vortex ring characteristics. The maximum propulsive efficiency was observed to occur when vortex rings were formed of the largest physical size, just before the leading vortex ring would pinch off from its trailing jet. These experiments demonstrate the importance of vortex ring pinch off in self-propelled vehicles, where coflow modifies the vortex dynamics.
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Meng, Yu-shan, Zhong-wei Wang, Wei Huang, Yao-bin Niu i Li Yan. "Coupled fluid–thermal analysis of the reduction mechanism for the drag and heat flux induced by jet interaction in a hypersonic reusable launch vehicle". AIP Advances 12, nr 10 (1.10.2022): 105124. http://dx.doi.org/10.1063/5.0124608.
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The analysis of heat transfer is crucial to hypersonic vehicles that operate under high pressure and aerodynamic heat flux due to severe aero-heating. The jet concept has been applied to reduce drag and increase thermal protection. In this paper, a flow control mechanism introduced through a jet strategy equipped on the blending area with a freestream Mach number of 6 is analyzed numerically. The thermal response of the hypersonic vehicle is numerically investigated with a three-dimensional fluid–thermal coupling approach based on a loosely coupled fluid–thermal analysis. The results indicate that, throughout the coupling process, the reduced temperature growth inside the structure contributes to lowered fluid temperature gradient, thus depressing external aerodynamic heating and gradually decreasing the rate of variation in heat flux as a consequence. The calculations focus on the influence of drag reduction on the aerodynamic characteristics of the hypersonic vehicle, and the thermal protection effects of different methods are compared. The study finds that manipulating the shock structure through jet interaction is practical and promising for alleviating high flight resistance and severe aero-heating, and the jet strategy is an advantageous means of reducing drag and thermal protection for the blending area. A maximum 2.22% increase in lift coefficient and 1.98% decrease in drag coefficient are obtained, and the lift-to-drag ratio of the vehicle is improved by 4.23% with the porous jet strategy. Moreover, this strategy remarkably reduces overall heat flux to less than 108 kW/m2 along the characteristic centerline of the jet orifices.
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Abbas, Mohammad, i David W. Riggins. "Analysis of Energy Utilization and Losses for Jet-Propelled Vehicles". Aerospace 8, nr 11 (12.11.2021): 342. http://dx.doi.org/10.3390/aerospace8110342.
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The global control volume-based energy utilization balance for an aerospace vehicle is extended to allow for the analysis of jet-propelled vehicles. The methodology is first developed for analyzing the energy utilization and entropy generation characteristics of jet engines without airframe considerations. This methodology, when combined with separate energy utilization analysis for an unpowered airframe, allows for the assessment of a powered vehicle. Wake entropy generation for a powered vehicle is shown to be the summation of the wake entropy generation associated with the propulsion system (no airframe) and the unpowered airframe. The fundamental relationship between overall entropy generation and the flight conditions required for maximum range and endurance of a powered vehicle are also derived. Example energy utilization results obtained for a modeled turbojet engine in off-design operation are provided; wake and engine component entropy generation characteristics are directly related to engine operation and flight conditions. This engine model is then integrated with a legacy (twin-engine) Northrop F-5E Tiger II airframe. The overall entropy generation temporal rate for the vehicle is minimized, as predicted by our analysis, at flight conditions corresponding to maximum endurance. For flight conditions corresponding to maximum range, the overall entropy spatial rate is minimized.
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Xue, Fei, Yunlong Zhang, Ning Cao i Liugang Li. "Solving the Moment Amplification Factor of a Lateral Jet by the Unsteady Motion Experimental Method". Applied Sciences 12, nr 16 (22.08.2022): 8387. http://dx.doi.org/10.3390/app12168387.
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In this paper, unsteady motion tests of a lateral jet adjusting an air vehicle’s attitude are carried out. Curves of pitch moment amplification factors (KM) for a lateral jet versus angle of attack (α) are obtained using a wind tunnel free-flight test technique with a jet and data processing method. This new method overcomes the disadvantage of previous experiments that can study only one unsteady characteristic. The free-flight test technique in the proposed method ensures that the test model can be coupled in real-time with multiple parameters (unsteady flow caused by the jet, unsteady air vehicle aerodynamic force, and unsteady air vehicle motion). This approach simulates an actual air vehicle’s complete jet test process and ensures more authentic and reliable test results. In the new data processing method, continuous data curves are fitted to discrete data points, making it easier to convert the angular displacement versus time curve into the pitch moment versus α curve to obtain KM. The results show that when the pressure of the micro high-pressure gas cylinder is 2.0 MPa, KM is below 1, indicating that the lateral jet does not significantly promote the pitching moment. When the gas cylinder pressure is 4.0 MPa and the angle of attack is 5° < |α| < 16°, KM is greater than 1, and the lateral jet promotes the pitching moment. When 16° < |α| < 20°, KM is less than 1, and the lateral jet does not significantly contribute to the pitching moment. It was further found that KM decreases slowly with increasing α. When |α| > 30°, the influence of the jet on the pitching moment nearly disappears.
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Sioma, Andrzej, i Wojciech Lepiarz. "Vision Analysis of a Biomimetic Water Vehicle Propeller". Solid State Phenomena 198 (marzec 2013): 144–49. http://dx.doi.org/10.4028/www.scientific.net/ssp.198.144.
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Water and underwater vehicles are driven by propellers. Various models use propellers with 2 to 7 blades with either fixed or controllable pitch. Another known solution are water-jet propellers. Water is sucked from the front of the vehicle and ejected through a nozzle at the rear. A propeller is usually the water pumping component. This paper presents the design of a novel type of water-jet propeller, inspired by the way animals move in the aquatic environment. It discusses the mechanisms of propeller operation and its structural solutions. It also presents theoretical simulation studies and actual studies on a real object, which enabled assessment of the propellers parameters.
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Fikri, Hasnul, Wanda Afnison, Wagino Wagino i Hendra Dani Saputra. "Analisis Penggunaan Variasi Turbo Cyclone Terhadap Performa Kendaraan". JTPVI: Jurnal Teknologi dan Pendidikan Vokasi Indonesia 1, nr 1 (13.02.2023): 105–18. http://dx.doi.org/10.24036/jtpvi.v1i1.18.
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Penelitian ini dilatar belakangi banyaknya kendaraan dengan usia pakai dan pola perawatan yang tidak rutin yang berakibat turunannya performa dan emisi yang meningkat. Penelitian ini bertujuan untuk mengetahui pengaruh penggunaan Turbo Cyclone terhadap performa kendaraan serta simulasi bentuk aliran udara yang melewati Turbo Cyclone. Peneliti menggunakan variasi berupa Turbo Cyclone merek Jet Ranger dan JSC. Penelitian ini menggunakan metode eksperimen yang dilakukan 3 kali pengujian pada masing – masing variabel, kendaraan yang digunakan yaitu Honda Beat PGM-FI. Variabel penelitian yaitu Turbo Cyclone Jet Ranger dan Turbo Cyclone JSC, performa kendaraan. Hasil penelitian menunjukkan, penggunaan Turbo Cyclone menyebabkan torsi dan daya maksimum berkurang jika. Emisi gas buang menggunakan Turbo Cyclone Jet Ranger dan tanpa Turbo Cyclone. Penggunaan bahan bakar spesifik terbaik dengan memasang Turbo Cyclone JSC. The background of this research is the large number of vehicles with long service life and non-routine maintenance patterns which result in decreased performance and increased emissions. This study aims to determine the effect of using a Turbo Cyclone on vehicle performance and to simulate the shape of the airflow passing through the Turbo Cyclone. The researcher used variations in the form of Turbo Cyclone, Jet Ranger and JSC brands. This study used an experimental method which was tested 3 times on each variable, the vehicle used was the Honda Beat PGM-FI. The research variables are Turbo Cyclone Jet Ranger and Turbo Cyclone JSC, vehicle performance. The results showed that the use of Turbo Cyclone causes maximum torque and power to decrease if. Exhaust emissions use Turbo Cyclone Jet Ranger and without Turbo Cyclone. Best use of specific fuel by installing Turbo Cyclone JSC.
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Huang, Jian. "Research on Water Sprays Shielding Device for Transport Vehicle". Applied Mechanics and Materials 707 (grudzień 2014): 317–20. http://dx.doi.org/10.4028/www.scientific.net/amm.707.317.
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Water sprays shielding device for transport vehicle, by use of its own power system and storage devices, make the gases within the air tank filling the water storage tank, and jet out from the small hole of roof-shaped spray tube, by means of cyclone atomizing, to form water sprays wall with shielding effect at the top and around the transport vehicle, In order to eliminate exposure symptoms for transport vehicle in the optical, infrared and radar band, to improve the battlefield viability of transport vehicles.
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Zhu, Jiachen, Zhiwei Shi, Quanbing Sun, Jie Chen, Yizhang Dong i Junquan Fu. "Yaw control of a flying-wing unmanned aerial vehicle based on reverse jet control". Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 234, nr 6 (7.02.2020): 1237–55. http://dx.doi.org/10.1177/0954410019899513.
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Due to its layout, there are difficulties in realizing heading attitude control of a flying-wing unmanned aerial vehicle. In this paper, a reverse jet control scheme has been designed: (1) to replace the resistance rudders that are used for the yaw control of a conventional flying-wing unmanned aerial vehicle, (2) to assist and optimize heading attitude control, eliminate the adverse effects of the control surface and enhance stealth performance, and (3) to promote the use of rudderless flight for flying-wing unmanned aerial vehicles. To explore the control mechanism and the flow field of the reverse jet scheme, three-dimensional numerical simulations and low-speed wind tunnel experiments were carried out. First, the numerical simulations evaluated the feasibility and effectiveness of the reverse jet control scheme and explored and optimized the excitation parameters for the scheme. Then the forces were measured in a wind tunnel, and particle image velocimetry experiments were carried out. A reverse jet actuator was independently designed to verify the results of the numerical simulation. The results show that when the reverse jet excitation is applied, the jet obstructs the mainstream, destroys the flow field at the excitation position, and causes early separation of the flow, which increases the pressure drag on the wings and produces a control effect. The control effect mainly depends on the separation degree of the leeward surface. The larger the jet momentum coefficient is, the smaller the jet angle is, and the closer the excitation position is to the leading edge, the greater the separation degree of the leeward surface is, the better the heading attitude control effect is.
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Ji, Yi-min, Hua Yang, Zheng Li, Zheng-hong Gao i Shu-sheng Chen. "Flow Mechanism and Feasibility Investigation of Hypersonic Jet Control Surface". Journal of Physics: Conference Series 2235, nr 1 (1.05.2022): 012065. http://dx.doi.org/10.1088/1742-6596/2235/1/012065.
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Abstract Hypersonic vehicle is a kind of vehicle that can fly at more than Mach 5 in the atmosphere. To solve the control problem of hypersonic vehicle, this work investigates the feasibility of hypersonic jet control surface. The numerical simulation method based on compressible Reynolds averaged Navier-Stokes equations with SST turbulence model is adopted. Firstly, the mechanism of hypersonic flow around airfoil with different deflection angles of aerodynamic control surface, which is arranged at the rear 30% of the airfoil behand a 2% chord gap, is analyzed and studied in detail. Then, a jet nozzle is set on the trailing edge of the airfoil to calculate and analyse the jet control effect of different total pressure ratio with 1.5mm gap (Mach 5, total pressure ratio from 1 to 300, altitude 40km). Thus, the flow mechanism, aerodynamic characteristics and control efficiency of the jet control surface is obtained. The results demonstrate that the aerodynamic control surface is effective in the hypersonic flow, and the control effect is proportional to the deflection angle of the control surface. Besides, the jet control surface also has control efficiency, which changes linearly with the total pressure ratio of the jet. And with the increase of jet total pressure ratio, the jet control surface can achieve the same control ability as the aerodynamic control surface. It reveals that the jet control surface is potentially a good control technique for hypersonic vehicle.
13
Park. "Empirical Prediction of Acoustic Load of Launch Vehicle Including Jet Impingement". Journal Of The Acoustical Society Of Korea 33, nr 3 (2014): 153. http://dx.doi.org/10.7776/ask.2014.33.3.153.
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Luo, Hai, Jiangming Ding, Jiabing Jiang, Lingxun Li, Jie Gong i Ning Lyu. "Resistance Characteristics and Improvement of a Pump-Jet Propelled Wheeled Amphibious Vehicle". Journal of Marine Science and Engineering 10, nr 8 (10.08.2022): 1092. http://dx.doi.org/10.3390/jmse10081092.
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Pump-jets have a relatively high propulsion efficiency at medium speed and in heavy-load conditions for wheeled amphibious vehicles. However, the geometry of amphibious vehicles is very special due to the installation requirements of the pump-jet, which results in an obvious resistance on the wheels. In order to reduce the resistance of the amphibious vehicle, the resistance characteristics of the wheels are studied. Regarding a pump-jet-propelled wheeled amphibious vehicle, its wheel resistance characteristics in a wide speed range are firstly analyzed based on experiments and numerical simulations. By comparing the resistance of the amphibious vehicle with and without wheels, it is found that the hydrodynamic effect of wheels can increase the total resistance of the amphibious vehicle by 14~28%. Then, the wheel hydrodynamic effect is divided into local effect and global effect. By analyzing the changes in resistance, pressure distribution and streamline, the influence and hydro-mechanism of each effect are explored in detail. It is found that the longitudinal convex and concave structures formed by the wheels and wheel wells have a large negative effect on the total resistance. According to the hydro-mechanism, two resistance improvement approaches are proposed, which includes increasing wheel retraction and installing flat plates on the wheel well bottom. Finally, the ultimate resistance improvement model can reduce resistance by no less than 10% and power by on less than 8% in design speed.
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Du, Jun-min, Guang-hua Li, Ben-Shuai Fu i Chuang You. "Numerical Simulation on Field Characteristics of the Horizontal Gas Jet Flow of Underwater Vehicle". Journal of Physics: Conference Series 2381, nr 1 (1.12.2022): 012006. http://dx.doi.org/10.1088/1742-6596/2381/1/012006.
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Abstract Solid rocket motors are important for the propulsion of underwater vehicles, especially for rapid maneuvering. To study the characteristics of the gas jet flow field generated by the engine of the underwater vehicle, a numerical calculation model considering gravity and phase transition was established. The basic laws of formation and evolution of jet bubbles were studied, and the unsteady characteristics of the jet flow field considering phase transition and the influence of inflow velocity and attack angle on the jet were analyzed. The results show the gas bubbles successively take on “concave” and “convex” shapes, and there exist “rebound” and “nesting” phenomena after the gas is accelerated and injected into water by the nozzle; the engine considering the phase transition process can obtain larger momentum and the degree of pressure fluctuation becomes smaller, which contributes to improving the propulsion efficiency of solid rocket motors by adding the gas-liquid phase transition model; the inlet flow has an inhibitory effect on the pressure pulsations of the flow field, and the influence of the wake on the vehicle which adopts rocket assist decreases as the speed increases; the upward deflection of the gas bubbles intensifies and the rupture of gas bubbles become closer to the nozzle outlet as the attack angle increases.
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Zhao, Hairui, Yao Shi i Guang Pan. "Numerical simulation of cavitation characteristics in high speed water entry of head-jetting underwater vehicle". Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University 39, nr 4 (sierpień 2021): 810–17. http://dx.doi.org/10.1051/jnwpu/20213940810.
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Autonomous underwater vehicle will be subjected to a huge impact load during high speed water entry, which will damage the structure and the internal instruments of the vehicle. Therefore, it is of great significance to study the buffer mechanism of the vehicle during the process of water-entry. In this paper, a kind of head-jetting device with disk cavitation is used. The complex cavitation forms, under the three-phase coupling of gas, liquid and solid, in the water entry process of the vehicle on which the device is installed. In this paper, the numerical simulation of high-speed water entry of the vehicle equipped with head jet device is carried out. Through the analysis of water entry cavitation under typical working conditions, the following conclusions are obtained. After the installation of head jet device, the water entry cavity of the vehicle changes gradually from cone to spindle shape. The air jet, compared with that without jet, can promote the formation of water inlet supercavitation, decrease the interaction area between the vehicle and water, and reduce the impact load during water entry. At the same water entry depth, the diameter of cavitation increases with the amount of air jet. The water entry velocity has a great influence on the difference of cavitation shape. The water entry depth closure phenomenon, when the water entry velocity is less than 100 m/s, can be observed in the depth of 3.5 times of the projectile length. The water entry angle has a significant effect on the cavitation shape. The cavity shows obvious asymmetry when the vehicle slants into the water, and the diameter and length of the bubbles decrease with the increase of the water entry angle. The research content of this paper provides technical support for the engineering practice of high-speed water entry and load reduction, and the conclusions are of great significance in related fields.
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Szudrowicz, Marek. "Material combination to mitigation of behind armour debris after shaped charge jet attack". MATEC Web of Conferences 182 (2018): 02009. http://dx.doi.org/10.1051/matecconf/201818202009.
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When a shaped charge jet perforates the steel armour plate, the residual jet is accompanied by a much wider cloud of behind armour debris (BAD) generated by stress wave interactions. BAD plays an important role in the evaluation of survivability of vehicle crew and components in a vehicle. The Behind Armor Debris (BAD) cloud caused by shaped charge jet impact was investigated. In order to simulate different configuration of material to mitigation of debris cloud the thickness of ceramics target tiles, glass and aramid laminate liners in contact with the armour plates was varied.
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Gangadharan, Sathya N., i Heinz L. Krein. "Jet-Propelled Remote-Operated Underwater Vehicles Guided by Tilting Nozzles". Marine Technology and SNAME News 26, nr 02 (1.04.1989): 131–44. http://dx.doi.org/10.5957/mt1.1989.26.2.131.
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This paper is a study and experimental analysis of a forced jet propulsion system with tilting-type nozzles for slow-moving remotely operated underwater vehicles (ROV's). A test setup simulating the motion of the underwater vehicle was fabricated to investigate the effect of nozzle configurations on the propulsion of such vehicles. Plexiglass nozzles of different conical contraction angles (θ = 4 to 28 deg), different conical expansion angles (θ = 3 to 9 deg), and a straight cylindrical section were used in the study. Tests were carried out underwater, and the parameters measured include thrust, flow rate, angular velocity, and total head. Different circular disk type drag plates were used to simulate the drag of the vehicle underwater. Efficiency of propulsion is the criterion for comparing the performance of each nozzle. An expression for the optimum efficiency was derived neglecting the effect of inlet head recovery, which can be assumed for slow-moving vehicles. The energy loss and loss coefficients in submerged propulsion nozzles were found both theoretically and experimentally. A proposal for the fabrication and testing of an innovative design of a jet-propelled ROV guided by tilting nozzles is presented. The design uses a stepper motor for tilting the nozzles. A comparison is made between stationary and swivel-type configurations. The nozzles were tested for optimum area ratio. The propulsion system and the ROV was designed and checked for stability. The study revealed that for a range of flow rates, one particular nozzle was the most efficient compared to other nozzles.
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Everitt, P., i S. B. Riffat. "Steam jet ejector system for vehicle air conditioning". International Journal of Ambient Energy 20, nr 1 (styczeń 1999): 14–20. http://dx.doi.org/10.1080/01430750.1999.9675312.
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Geng, Lingbo, Zhiqiang Hu i Yang Lin. "Hydrodynamic characteristic of synthetic jet steered underwater vehicle". Applied Ocean Research 70 (styczeń 2018): 1–13. http://dx.doi.org/10.1016/j.apor.2017.11.005.
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Oinuma, H., K. Nagai, T. Ishii i K. Takeda. "Jet-propulsion Unmanned Aerial Vehicle for flight experiments". Proceedings of JSME annual Conference on Robotics and Mechatronics (Robomec) 2004 (2004): 213. http://dx.doi.org/10.1299/jsmermd.2004.213_2.
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Zhang, Jiayue, Jikui Ma i Yaofeng Liu. "Research on RCS Jet Interaction Characteristics of the Capsule Entry Vehicle at Subsonic and Transonic Speed". Journal of Physics: Conference Series 2381, nr 1 (1.12.2022): 012111. http://dx.doi.org/10.1088/1742-6596/2381/1/012111.
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Abstract In this paper, the RCS jet interaction characteristics of the capsule entry vehicle were studied by numerical simulation. The jet interference characteristics under different re-entry ballistic parameters were compared. The influence of the angle of attack on the jet flow field structure and aerodynamic characteristics was analyzed.
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Timoshenko, V. I., V. P. Halynskyi i Yu V. Knyshenko. "Theoretical studies on rocket/space hardware aerogas dynamics". Technical mechanics 2021, nr 2 (29.06.2021): 46–59. http://dx.doi.org/10.15407/itm2021.02.046.
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This paper presents the results of theoretical studies on rocket/space hardware aerogas dynamics obtained from 2016 to 2020 at the Department of Aerogas Dynamics and Technical Systems Dynamics of the Institute of Technical Mechanics of the National Academy of Sciences of Ukraine and the State Space Agency of Ukraine along the following lines: rocket aerodynamics, mathematical simulation of the aerogas thermodynamics of a supersonic ramjet vehicle, jet flows, and the hydraulic gas dynamics of low-thrust control jet engines. As to rocket aerodynamics, computational methods and programs (CMPs) were developed to calculate supersonic flow past finned rockets. The chief advantage of the CMPs developed is computational promptness and ease of adding wings and control and stabilization elements to rocket configurations. A mathematical simulation of the aerogas thermodynamics of a supersonic ramjet vehicle yielded new results, which made it possible to develop a prompt technique for a comprehensive calculation of ramjet duct flows and generalize it to 3D flow past a ramjet vehicle. Based on marching methods, CMPs were developed to simulate ramjet duct flows with account for flow past the airframe upstream of the air inlet, the effect of the combustion product jet on the airframe tail part, and its interaction with a disturbed incident flow. The CMPs developed were recommended for use at the preliminary stage of ramjet component shape selection. For jet flows, CMPs were developed for the marching calculation of turbulent jets of rocket engine combustion products with water injection into the jet body. This made it possible to elucidate the basic mechanisms of the effect of water injection, jet–air mixing, and high-temperature rocket engine jet afterburning in atmospheric oxygen on the flow pattern and the thermogas dynamic and thermalphysic jet parameters. CMPs were developed to simulate the operation of liquid-propellant low-thrust engine systems. They were used in supporting the development and ground firing tryout of Yuzhnoye State Design Office’s radically new system of control jet engines fed from the sustainer engine pipelines of the Cyclone-4M launch vehicle upper stage. The computed results made it possible to increase the informativity of firing test data in flight simulation. The CMPs developed were transferred to Yuzhnoye State Design Office for use in design calculations.
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Fu, Qiang, Xue Ling Sun i Ming Xiu Cai. "Simulation Study on Jet Power Drive System of Quarter Vehicle". Advanced Materials Research 712-715 (czerwiec 2013): 2124–27. http://dx.doi.org/10.4028/www.scientific.net/amr.712-715.2124.
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Jet power drive system of quarter vehicle is put forwarded to improve starting drive efficiency. It analyzes JPD working principle, adds a jet power and researches for the basic simulation of control model with slip-rate as the control object based on PID control theory. The academic feasibility of jet power drive system is expatiated, that is based on the principle of compressed air power which is applied to the starting drive system, then establishes dynamics model of a new automotive anti-slip drive system and simulation model of ASR&JPD by the MATLAB/Simulink. The simulation tests are designed to compare with the curves of vehicle speed and driving wheel velocity using the JPD. The graph proves that JPD can reduce starting drive distance at 21%--77% and starting drive time at 12%--70%. Augmentation rate of vehicle acceleration exceeds 50%. The results show that the ASR&JPD can increase starting drive efficiency.
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Djojodihardjo, Harijono, Riyadh Ibraheem Ahmed, Abd Rahim Abu Talib i Azmin Shakrine Mohd Rafie. "First principle analysis of Coandă Micro Air Vehicle aerodynamic forces for preliminary sizing". Aircraft Engineering and Aerospace Technology 89, nr 2 (6.03.2017): 231–45. http://dx.doi.org/10.1108/aeat-03-2015-0080.
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Purpose The purpose of this paper is to reformulate the governing equations incorporating major variables and parameters for the design a Micro Air Vehicle (MAV), to meet the desired mission and design requirements. Design/methodology/approach Mathematical models for various spherical and cylindrical Coandă MAV configurations were rederived from first principles, and the performance measures were defined. To verify the theoretical prediction to a certain extent, a computational fluid dynamic (CFD) simulation for a Coandă MAV generic models was performed. Findings The major variables and parameters of Coandă MAV have been formulated into practical guidelines, which relate the lift (or thrust) produced for certain input variables, particularly the Coandă MAV jet momentum coefficient. The influences of the geometrical parameters are elaborated. Research limitations/implications The present analysis on Coandă jet-configured MAV is focused on the lift generation due to the Coandă jet effect through a meticulous analysis. The effects of viscosity, the Coandă jet thickness, the radius of curvature of the surface and the stability of Coandă jet are not considered and will be the subject of the following work. Practical implications The results obtained can be used for sizing in the preliminary design of Coandă MAVs. Originality/value Physical and mathematical models were developed which can describe the physical phenomena of the flow field near the Coandă MAV surfaces influenced by Coandă jet sheets and for obtaining a relationship between relevant variables and parameters to the lift of practical interest.
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Wiebe, Wilhelm, Thomas v. Unwerth i Sven Schmitz. "Hydrogen pump for hydrogen recirculation in fuel cell vehicles". E3S Web of Conferences 155 (2020): 01001. http://dx.doi.org/10.1051/e3sconf/202015501001.
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A promising alternative to fossil-fuelled vehicles are battery-powered vehicles and fuel cell (FC) vehicles. The major differences between fuel cell and battery-powered vehicles are the range and refuelling times of each vehicle type. With a hydrogen (Hed vehicles are the range and refuelling times of each vehicle type. With a hydrogen (H2) fuelling time of approx. 5 minutes it is possible to cover a distance of up to 800 km with a fuel cell vehicle. These properties make a fuel cell vehicle comparable to a fossil fuel powered vehicle. Furthermore, due to short fuelling times and long range capabilities, fuel cell vehicles are more suitable for long-distance, trucking and agriculture than battery-powered vehicles. The aim of current research is to increase the profitability of fuel cells by reducing costs and improving performance. To ensure a high performance of the fuel cell stack, more hydrogen is supplied to the stack than is needed for the reaction. Therefore, unused hydrogen is pumped back to the anode inlet of the FC-stack using a jet pump or a recirculation blower. In this study, the application of an electrochemical compressor or hydrogen pump (HP) for hydrogen recirculation is suggested. The hydrogen pump is an innovative H2 transport technology with the additional functions of compression and purification in the recirculation system. Hydrogen pumps are very efficient compared to mechanical compressors due to the almost isothermal conditions they operate under. Furthermore, due to the modular design, hydrogen compressors can utilize a minimal amount of space in vehicles.
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RUIZ, LYDIA A., ROBERT W. WHITTLESEY i JOHN O. DABIRI. "Vortex-enhanced propulsion". Journal of Fluid Mechanics 668 (22.12.2010): 5–32. http://dx.doi.org/10.1017/s0022112010004908.
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It has been previously suggested that the generation of coherent vortical structures in the near-wake of a self-propelled vehicle can improve its propulsive efficiency by manipulating the local pressure field and entrainment kinematics. This paper investigates these unsteady mechanisms analytically and in experiments. A self-propelled underwater vehicle is designed with the capability to operate using either steady-jet propulsion or a pulsed-jet mode that features the roll-up of large-scale vortex rings in the near-wake. The flow field is characterized by using a combination of planar laser-induced fluorescence, laser Doppler velocimetry and digital particle-image velocimetry. These tools enable measurement of vortex dynamics and entrainment during propulsion. The concept of vortex added-mass is used to deduce the local pressure field at the jet exit as a function of the shape and motion of the forming vortex rings. The propulsive efficiency of the vehicle is computed with the aid of towing experiments to quantify hydrodynamic drag. Finally, the overall vehicle efficiency is determined by monitoring the electrical power consumed by the vehicle in steady and unsteady propulsion modes. This measurement identifies conditions under which the power required to create flow unsteadiness is offset by the improved vehicle efficiency. The experiments demonstrate that substantial increases in propulsive efficiency, over 50 % greater than the performance of the steady-jet mode, can be achieved by using vortex formation to manipulate the near-wake properties. At higher vehicle speeds, the enhanced performance is sufficient to offset the energy cost of generating flow unsteadiness. An analytical model explains this enhanced performance in terms of the vortex added-mass and entrainment. The results suggest a potential mechanism to further enhance the performance of existing engineered propulsion systems. In addition, the analytical methods described here can be extended to examine more complex propulsion systems such as those of swimming and flying animals, for whom vortex formation is inevitable.
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Krueger, Paul S., Ali A. Moslemi, J. Tyler Nichols, Ian K. Bartol i William J. Stewart. "Vortex Rings in Bio-Inspired and Biological Jet Propulsion". Advances in Science and Technology 58 (wrzesień 2008): 237–46. http://dx.doi.org/10.4028/www.scientific.net/ast.58.237.
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Pulsed-jets are commonly used for aquatic propulsion, such as squid and jellyfish locomotion. The sudden ejection of a jet with each pulse engenders the formation of a vortex ring through the roll-up of the jet shear layer. If the pulse is too long, the vortex ring will stop forming and the remainder of the pulse is ejected as a trailing jet. Recent results from mechanical pulsedjets have demonstrated that vortex rings lead to thrust augmentation through the acceleration of additional ambient fluid. This benefit is most pronounced for short pulses without trailing jets. Simulating vehicle motion by introducing background co-flow surrounding the jet has shown that vortex ring formation can be interrupted, but only if the co-flow is sufficiently fast. Recent in situ measurements on squid have captured vortical flows similar to those observed in the laboratory, suggesting thrust augmentation may play a role in their swimming performance. Likewise, recent measurements with a mechanical self-propelled pulsed-jet vehicle (“robosquid”) have shown a cruise-speed advantage obtained by pulsing.
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Roy, Subrata, Karim Nasr, Paresh Patel i Bashar AbdulNour. "Rectangular Jet Impingement Heat Transfer on a Vehicle Windshield". Journal of Thermophysics and Heat Transfer 16, nr 1 (styczeń 2002): 154–57. http://dx.doi.org/10.2514/2.6665.
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Moslemi, Ali A., i Paul S. Krueger. "Propulsive efficiency of a biomorphic pulsed-jet underwater vehicle". Bioinspiration & Biomimetics 5, nr 3 (16.08.2010): 036003. http://dx.doi.org/10.1088/1748-3182/5/3/036003.
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Deng, Jia, Shi Hua Bi i Shao Zhen Yu. "Research on the Effect of Moulded Surfaces of Deflectors". Advanced Materials Research 951 (maj 2014): 53–57. http://dx.doi.org/10.4028/www.scientific.net/amr.951.53.
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Whether the gas jet is deflected smoothly or not directly affects the success or failure of launch, during the progress of the land-based missile with the vehicle-mounted vertically thermal launch. This paper uses 3-D dynamical simulation of gas jet to analyse basic deflecting features of triple-faced deflectors and double-faced ones with different moulded surfaces. The result shows that, triple-faced deflectors deflect quite smoothly and requite large area of the firing position. With some differences, double-faces deflectors protect the vehicle and wheels much better and requite more of the firing position of the deflector’s bilateral.
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Uss, A. Yu, i A. V. Chernyshev. "A Vortex Jet Device Applied in the Development of Active Hydro-Pneumatic Dampers Used in Rehabilitation Equipment". Herald of the Bauman Moscow State Technical University. Series Mechanical Engineering, nr 1 (136) (marzec 2021): 185–204. http://dx.doi.org/10.18698/0236-3941-2021-1-185-204.
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The paper overviews and analyses the current status of the development and research of active hydro-pneumatic dampers, which are used in rehabilitation equipment, where vortex jet devices can be applied as control valves. The study focuses on a vortex jet device whose distinctive feature is the absence of mechanically moving parts, describes the principle of its operation, and gives the rationale for using it in the active hydro-pneumatic damper of the knee module prosthesis. From a review of scientific and technical literature, a conclusion is drawn that active hydro-pneumatic dampers are used not only in rehabilitation equipment but also in vehicle shock absorbers. The experience gained in the design and development of active hydro-pneumatic dampers for vehicle shock absorbers was applied in the design and development of an active hydro-pneumatic damper for the knee module. In order to identify the advantages and disadvantages, we examined some designs of active hydro-pneumatic dampers for vehicle shock absorbers. Analysis of technical solutions showed the advantage of vortex jet devices, e.g. high reliability, the ability to work with various working environments, low manufacturing and operating costs; enabled us to recommend a vortex jet device to be used as an actuator, i.e., a vortex valve, in the valve assembly of an active hydro-pneumatic damper. The use of a vortex jet device increases the reliability of the structure and reduces the energy consumption for the control of the structure. The proposed design of the hydro-pneumatic damper allows the use of interactive damping control. The study is the first to introduce the concept and describe the principle of operation of an active hydro-pneumatic damper using a vortex jet device
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LINDEN, P. F. "The efficiency of pulsed-jet propulsion". Journal of Fluid Mechanics 668 (26.01.2011): 1–4. http://dx.doi.org/10.1017/s0022112010005768.
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Nature is often an inspiration for scientists and especially so in fluid dynamics. We observe and admire the beauty of birds and fish as they move through the air and water, and wonder how these forms of locomotion evolved and whether they are optimised for efficiency. A common feature of this locomotion is that the thrust is generated by the flapping of a wing or fin, creating an unsteady flow. Other less readily observed animals such as salps or squid eject a pulsed jet, raising the question of whether there is an advantage of this unsteady forcing over a steady jet. This is the question addressed by Ruiz, Whittlesey & Dabiri (J. Fluid Mech., this issue, vol. 668, 2011, pp. 5–32) who have carried out detailed flow and power-consumption measurements with a self-propelled vehicle in water. The vehicle has a novel propulsion mechanism that allows a comparison of the efficiency of a pulsed and steady jet to be compared. They show that significant increases in efficiency are possible with the pulsed jet, even allowing for the additional power needed to create the pulsed flow. They also show that vortex rings are produced by the unsteady jet and that the additional entrainment of ambient fluid into the ring and the higher pressure at the front of the ring are the cause of this increased efficiency.
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Baldin, A. A. "Ecological aspect of launch vehicles development by criterion of minimal cost". Ecology and Noospherology 25, nr 3-4 (29.05.2014): 114–19. http://dx.doi.org/10.15421/031427.
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One of the topical problems in modern aerospace engineering is accordance between ecological requirements and performance of the vehicle. On the other hand, problem of economical efficiency leads to change of the main criterion of designing to the minimization of costs (instead of maximal performance). According to modern trends of “low-cost” vehicles, different concepts of the future cost-effective launch vehicles are considered. It is necessary to validate these concepts according to requirements of ecological safety for the purpose of detection of the dominant launch vehicle configuration. Typical configurations of the future 'low-cost' launch vehicle are presented by 6 conceptual groups (Koelle, 2001). Conceptual group 1 (CG1) is presented by the Ballistic “Single stage to orbit” (SSTO) reusable vehicle. All vehicles which use classical rocketry scheme of the propulsion trajectory are called “Ballistic” i.e. the ballistic vehicle is lifted to orbit under the impact of rocket engines thrust. CG1-vehicle is able to reach the low earth orbit (LEO) without stage separation reducing the number of required rocket engines. Technological feasibility of SSTO concepts is proven by numerous studies (Koelle, 2001). CG2 representatives are ballistic “Two stages to orbit” (TSTO) reusable vehicles. The difference between CG1 and CG2 consists in application of vacuum rocket engines in the second stage and, consequently, stage separation. CG2 are the most mass-effective vehicles. CG3 is presented by the winged SSTO vehicles with rocket propulsion by “Lifting body” aerodynamic scheme. Ascensional force is provided by the aerodynamic shape of the vehicle’s structure at high speeds. Winged TSTO vehicles with rocket propulsion and parallel or tandem staging form the CG4. The winged configuration provides wide landing capability for both stages. CG5 is presented by winged TSTO vehicles with airbreathing propulsion in the first stage and rocket-propelled second stage. Airbreathing jet engines provide high reusability ratio comparing with other concepts as well as the widest landing capability. Aerospace Plane with scramjet-rocket propulsion forms CG6. The vehicle is able to reach near-cosmic speed in rarefied layers of the atmosphere and then accelerate with rocket engines. The most ecologically important resemblance of represented concepts is reusability. This reduces space debris formation (due to lack of waste hardware). Reusable launch vehicles can also be used to return the spent satellites. Structural differences between the concepts form 3 criterions of comparison by ecological impact: 1) propellant toxicity; 2) safety of surface facilities (vehicle damage inside the atmosphere); 3) probability of space debris formation (vehicle damage outside the atmosphere). Comparison of the concepts by these criterions allows substantiating the most ecologically acceptable direction of research. Results of the comparison demonstrate that the most ecologically acceptable low-cost launch vehicle configuration is: Ballistic SSTO or TSTO reusable launch vehicle with “LOX+LH2” propellant. The results can be explained by following way: combustion products of the propellant “liquid oxygen + liquid hydrogen” are absolutely safe for environment. It also provides maximal performance of rocket engine (due to the highest specific impulse). Ballistic ascent scheme allows using relatively simple technologies and provides high reliability level. In combination with minimal time of atmospheric flight this provides high level of safety for surface facilities. These results may be used for substantiation of dominant research direction.
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Ni, Zi-jian, Shu-zhou Fang, Jian Guo i Zi-yu Wang. "Research on Drag Reduction and Heat Prevention of Hypersonic Vehicle Combined Model with Reverse Jet and Slot Blowing". Journal of Physics: Conference Series 2459, nr 1 (1.03.2023): 012140. http://dx.doi.org/10.1088/1742-6596/2459/1/012140.
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Abstract A novel strategy combining reverse jet with slotted blowing is proposed in this paper, and two-dimensional (RANS) is used to numerically investigate the flow characteristics of a reverse jet. The numerical results show the jet from the aircraft head ejects backward, pushing the shock away and reducing aerodynamic heating and shock wave resistance. The jet from the middle slot ejects backward and the effective solution reduces the viscous resistance of the fuselage. This new strategy not only further reduces the total resistance but also provides good thermal protection for the aircraft. Compared with the aircraft model, the stagnation point temperature and resistance are reduced by 25.0% and 28.0%, respectively, with the addition of multiple jets.
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Wang, Shasha, Mingyu Fu, Yuanhui Wang i Liangbo Zhao. "A Multi-Layered Potential Field Method for Water-Jet Propelled Unmanned Surface Vehicle Local Path Planning with Minimum Energy Consumption". Polish Maritime Research 26, nr 1 (1.03.2019): 134–44. http://dx.doi.org/10.2478/pomr-2019-0015.
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Abstract Focusing on the influence of wind and surface currents on local path planning in the marine environment, a multilayered potential field (MPF) method is proposed to minimize the energy consumption of a water-jet propelled unmanned surface vehicle (USV). A synthetic environment framework that can incorporate the information of the base potential field layer and the environment layer is constructed first. This framework provides a base for minimizing the energy consumption of the water-jet propelled USV through proper force weighting. For the purpose of USV path planning, the traditional potential field method is extended by including the velocity information of the USV and the approached obstacles to avoid collisions with dynamic obstacles. The proposed method integrates kinematic control to prevent considering the vehicle as a point mass or rigid body. Finally, simulation and comparison experiments are performed to demonstrate the energy-saving efficiency of the proposed local path planning approach for the water-jet propelled USV.
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Deng, Fan, Feng Xie, Wei Huang, Hao Dong i Dong Zhang. "Numerical exploration on jet oscillation mechanism of counterflowing jet ahead of a hypersonic lifting-body vehicle". Science China Technological Sciences 61, nr 7 (7.11.2017): 1056–71. http://dx.doi.org/10.1007/s11431-017-9135-0.
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SUZUKI, Akihiro, Masahiro OSAKABE i Hayato KONDO. "Propulsion System of Underwater Vehicle with Low Speed Water Jet". Proceedings of the National Symposium on Power and Energy Systems 2016.21 (2016): A113. http://dx.doi.org/10.1299/jsmepes.2016.21.a113.
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Korde, Umesh A. "Study of a jet-propulsion method for an underwater vehicle". Ocean Engineering 31, nr 10 (lipiec 2004): 1205–18. http://dx.doi.org/10.1016/j.oceaneng.2004.01.001.
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Edwige, Stéphie, Philippe Gilotte i Iraj Mortazavi. "Computational Analysis of Actuation Techniques Impact on the Flow Control around the Ahmed Body". Fluids 7, nr 2 (24.01.2022): 52. http://dx.doi.org/10.3390/fluids7020052.
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Active flow control with jet devices is a promising approach for vehicle aerodynamics control. In this work an extended computational study is performed comparing three different actuation strategies for active flow control around the square back Ahmed body at Reynolds number 500,000 (based on the vehicle height). Numerical simulations are run using a Large Eddy Simulation (LES) approach, well adapted to calculate the unsteady high Reynolds number flow control using periodic jet devices. computations are validated comparing to in-house experiments for uncontrolled and some controlled cases. The novelty of this investigation is mainly related to the in-depth study of the base flow and actuation approaches by an accurate LES method and their comparison to experiments. Here, several simulations are performed to estimate the effect of active controls on the flow topology and the drag reduction. Beside the continuous blowing jet, three periodic actuation techniques including periodic blowing and suction as well as the zero flux synthetic jet devices are explored. The slots are implemented discontinuously in order to achieve a better control efficiency linked to vortex generation. In this framework, spectral analyses on global aerodynamical quantities, rear pressure/drag coefficient behavior examination as well as wake structure investigations are performed in order to compare these jet actuations. As a result, shear layer variations are observed during the blowing phase, but the main flow topology change occurs with suction and synthetic jets. Rear back pressure is therefore substantially increased.
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Gao, Fei, Jing Xuan Zhou i Min Li. "Numerical Investigation of Geometric Factors for Design of High Performance Air-Jet Pumps Using in Vehicle-Mounted Vacuum Toilet". Advanced Materials Research 268-270 (lipiec 2011): 46–50. http://dx.doi.org/10.4028/www.scientific.net/amr.268-270.46.
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Air-jet pump as the pneumatic source of a vehicle-mounted vacuum toilet provides the vacuum to pump the fecal sewage out of toilet bowl via the compressed air passing through the pump under certain pressure. In this study, Computational Fluid Dynamics (CFD) technique is employed to investigate the effects of three important air-jet pump geometry parameters: the primary Nozzle Exit Position (NXP), the constant-area section length (L1) and the diffuser diverging angle (θ), on its performance. A CFD model is firstly established according to 1D analytical method, and then used to create 135 different air-jet pump geometries and tested under different operating conditions. The significance of this study is that these findings can be used to guide the adjustment of NXP, L1 and θ to obtain the best air-jet pump performance when the operating conditions are different.
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Zhao, Chen-geng, Zhong-yi Sun, Yi-fei Su, Yi-chen Wang i Gui-gao Le. "Study on bottom thermal environment of launch vehicle during high altitude flight". Journal of Physics: Conference Series 2364, nr 1 (1.11.2022): 012029. http://dx.doi.org/10.1088/1742-6596/2364/1/012029.
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Abstract Aiming at the problem of the thermal environment at the bottom of the launch vehicle in the high-altitude flight stage, taking the launch vehicle with core stage four-way machine as the model, the coupled convection / radiation heat transfer problem at the high-altitude of the launch vehicle is deeply studied through the numerical simulation method, the gas jet flow model of the launch vehicle in the high-altitude flight stage is established, and the flow field information of the rocket under different working conditions and the heat flow at the bottom of the rocket are obtained. The numerical results are compared with the experimental data to verify the effectiveness of the selected model and calculation method. The research shows that the external flow field of the rocket body will have a great impact on the thermal environment at the bottom. With the continuous increase of flight altitude, the convective heat flow at the bottom of the rocket body first rises and then decreases. In the high-altitude stage, the total heat flow at the bottom of the rocket body is dominated by radiant heat flow, the convective heat flow outside the main nozzle is dominant, and the radiant heat flow outside the traveling jet nozzle is dominant.
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Zhao, Xue Jun, Xiao Guo Guo i Chang Zhao. "A New Support Structure in Waverider Force Measurement". Applied Mechanics and Materials 318 (maj 2013): 96–99. http://dx.doi.org/10.4028/www.scientific.net/amm.318.96.
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In this paper a new support structure was given to solve the problem met in the force measurement with engine jet. The force measurements of waverider were undertaken in the hypersonic wind tunnel. The test condition was at Ma=6, angle of attack α=-6°-6°, at which we researched the effects on the vehicle aerodynamics of inlet cowl opening and closing, support system, engine jet, and pressure ratios. To decrease the effects of strut on the jet flow-field, we took sharp belly strut to support the model in the wind tunnel. The belly strut could support the waverider model, force measurement balance, and it could make the inlet flow set up, and provide the high pressure jet. The test results showed that the belly sharp strut had little effects on the flowfield and could inject the inlet flow, and could provide very high quality jet.
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Zhang, Wenqing, Xiaowei Wang, Zhijun Zhang i Tianyi Su. "Numerical Investigation on the Jet Characteristics and the Heat and Drag Reductions of Opposing Jet in Hypersonic Nonequilibrium Flows". Aerospace 9, nr 10 (26.09.2022): 554. http://dx.doi.org/10.3390/aerospace9100554.
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We adopted the transient numerical method for the simulation of an ELECTRE vehicle with an opposing jet at an altitude of 53.3 km and 13 Ma to explore the jet characteristics as well as the performance in heat and drag reductions of the opposing jet in hypersonic nonequilibrium flows. The time-accurate, nonequilibrium N-S equations coupled with the five-species Park chemical kinetic model and vibrational energy excitation were applied, and an open source solver Hy2FOAM based on the OpenFOAM platform was adopted. Three opposing jets with different jet radii (R7 jet, R14 jet, and R21 jet) were investigated. The results show that with the increasing jet flow rate, the jet mode of the opposing jet with a small jet radius varies from the overflow mode to the long penetration mode (LPM) and finally to the short penetration mode (SPM), while that with a large jet radius directly changes from the overflow mode to the SPM. The state of the jet in the overflow mode is stable, whereas in SPM and LPM, it is unstable. The investigation of the heat and drag reductions for the R7, R14, and R21 jets shows that except for the jet in LPM, the jet in SPM and overflow mode can provide effective thermal protection, and the thermal protection is enhanced with the increasing jet flow rate. Moreover, the jet in both LPM and SPM can effectively reduce the aerodynamic drag, but the jet in overflow mode cannot provide effective drag reduction. Moreover, the jet with a large radius and in the overflow mode has a better thermal protection effect, and a small jet radius contributes to the drag reduction.
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Elsayed, Omer, Ashraf A. Omar, Ali Jeddi, Saad EL HESSNI i Fatima Zahra Hachimy. "Drag Reduction by Application of Different Shape Designs in a Sport Utility Vehicle". International Journal of Automotive and Mechanical Engineering 18, nr 3 (19.09.2021): 8870–81. http://dx.doi.org/10.15282/ijame.18.3.2021.03.0680.
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Road vehicles drag is a direct consequence of a large wake area generated behind. This area is created owing to the vehicle shape, which is determined by the class, functional and aesthetic of the vehicle. Aerodynamic characteristics are a ramification and not the reason for the vehicle architecture. To enhance pressure recovery in the wake region, hence reduce drag, three different passive flow control techniques were applied to sport-utility-vehicle (SUV). A three-dimensional SUV was designed in CATIA, and a numerical flow simulation was conducted using Ansys-Fluent to evaluate the aerodynamic effectiveness of the proposed flow control approaches. A closed rectangular flap as an add-on device modifies the wake vortex system topology, enhances vortex merging, and increases base pressure which leads to a drag reduction of 15.87%. The perforated roof surface layer was used to delay flow separation. The measured base pressure values indicate a higher-pressure recovery, which globally reflected in a drag reduction of 19.82%. Finally, air guided through side rams was used as steady blowing. A steady passive air jet introduced at the core of the longitudinal trailing vortices leads to a confined wake area. The net effects appear in a global increase in the base pressure values and the pronounced drag reduction of 22.67%.
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Nichols, J. Tyler, i Paul S. Krueger. "Effect of vehicle configuration on the performance of a submersible pulsed-jet vehicle at intermediate Reynolds number". Bioinspiration & Biomimetics 7, nr 3 (2.05.2012): 036010. http://dx.doi.org/10.1088/1748-3182/7/3/036010.
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Zhang, Li Jun, Xiao Jiao Chen, Min Li, Yue Fan i Qiang Fu. "Research on Numerical Calculation Method to Aerodynamic Noise in High Velocity Environment". Advanced Materials Research 655-657 (styczeń 2013): 809–12. http://dx.doi.org/10.4028/www.scientific.net/amr.655-657.809.
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At present, the flight velocity and flight performance of an aircraft are higher, so that aerodynamic noise caused by an engine jet in the take-off and flight processes can reach 160 dB. The high strength of the jet aerodynamic noise is very harmful to vehicle drivers, vehicle structures and airborne equipments. Two numerical calculation methods to aerodynamic noise, the FW-H acoustic analogy method and the FW-H acoustic analogy and boundary element combining method, were introduced. These two methods were used to predict the aerodynamic noise, and the numerical calculation results were compared with the physical experimental results. Results show that the FW-H acoustic analogy method can predict aerodynamic noise. However, it cannot predict the sound field distribution. The FW-H acoustic analogy and boundary element combining method is able to predict the sound field distribution with sound reflection.
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Zhirnikov, B. L., O. K. Kudin i Yu N. Nesterov. "EXPERIMENTAL STUDY OF THE JET FLOW CONTROL IN A VEHICLE AFTBODY". TsAGI Science Journal 40, nr 6 (2009): 763–73. http://dx.doi.org/10.1615/tsagiscij.v40.i6.100.
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Kowaleczko, Grzegorz. "PRELIMINARY DETERMINATION OF THE JET-2 UNMANNED AERIAL VEHICLE DYNAMIC PERFORMANCES". Journal of KONES. Powertrain and Transport 21, nr 4 (1.01.2014): 255–62. http://dx.doi.org/10.5604/12314005.1130491.
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Nenashev, Pavel, Sergey Abdulov i Alexander Taratorkin. "Increase of durability of an amphibious vehicle water jet propulsion drive". IOP Conference Series: Materials Science and Engineering 709 (3.01.2020): 033036. http://dx.doi.org/10.1088/1757-899x/709/3/033036.
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