Journal articles on the topic 'Jet engine inlet'
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1
Langston, Lee S. "Jet Engine Fuel Burn Reduction Through Boundary Layer Ingestion." Mechanical Engineering 136, no. 04 (April 1, 2014): 54–58. http://dx.doi.org/10.1115/1.2014-apr-5.
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This article explains various technical aspects of the boundary layer ingestion (BLI) concept. Using BLI, airliner designs featuring close-coupled, rear-mounted turbofans are being considered, with a fuselage sculpted to sweep a large part of the fuselage boundary layer into engine inlets for reduced fuel consumption. With an engine array fuselage-centered, rather than splayed out on wings, reduced rudder control is needed in the event of a single engine outage. This reduces the size of a BLI tail assembly, saving weight and reducing drag. A near-future goal of the BLI studies is to determine if modern engine front-mounted fans can be designed to operate efficiently and stably under BLI inlet conditions. The D8 design is aimed at the huge single-aisle, narrow-body market, now dominated by the Boeing 737 and Airbus 320 families. Airframe and engine designers strive to achieve 'clean' inlet flow conditions for jet engines.
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Reddy, P. Nithish. "Hypersonic Scram-Jet Engine Inlet Design." International Journal for Research in Applied Science and Engineering Technology 7, no. 6 (June 30, 2019): 1619–35. http://dx.doi.org/10.22214/ijraset.2019.6273.
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Smith, Jerome P., Ricardo A. Burdisso, and Chris R. Fuller. "Active control of jet engine inlet noise." Journal of the Acoustical Society of America 101, no. 5 (May 1997): 3122. http://dx.doi.org/10.1121/1.418918.
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Biglarian, M., A. Najafi, and S. M. Negharchi. "Numerical Analysis of inlet vortex in the scaled engine." IOP Conference Series: Materials Science and Engineering 1196, no. 1 (October 1, 2021): 012033. http://dx.doi.org/10.1088/1757-899x/1196/1/012033.
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Abstract A jet engine that works near the ground and generates high thrust at low speed can experience the flow separation from the ground surface up to its inlet and, as a result, the formation of a famous vortex. This vortex extended from the ground surface to the fan inlet is known as the inlet vortex. In the present study, a jet engine model scaled down by 1/30 relative to the real jet engine with 3 million hexahedral elements is simulated using Computational Fluid Dynamics (CFD). The obtained results agree with empirical relationships, and the inlet vortex can be analyzed in scales much lower than the original prototype. Also, the inlet vortex gets weakened by increasing free stream velocity and completely degraded at higher velocities. By understanding how this phenomenon occurs and can be dealt with, the Foreign Object Damages (FOD) such as compressor surge, fan vibration, and particle ingestion into the engine core can be prevented.
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Tam, Christopher K. W., Sarah A. Parrish, Edmane Envia, and Eugene W. Chien. "Physical processes influencing acoustic radiation from jet engine inlets." Journal of Fluid Mechanics 725 (May 14, 2013): 152–94. http://dx.doi.org/10.1017/jfm.2013.181.
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AbstractNumerical simulations of acoustic radiation from a jet engine inlet are performed using advanced computational aeroacoustics algorithms and high-quality numerical boundary treatments. As a model of modern commercial jet engine inlets, the inlet geometry of the NASA Source Diagnostic Test is used. Fan noise consists of tones and broadband sound. This investigation considers the radiation of tones associated with upstream-propagating duct modes. The primary objective is to identify the dominant physical processes that determine the directivity of the radiated sound. Two such processes have been identified. They are acoustic diffraction and refraction. Diffraction is the natural tendency for an acoustic duct mode to follow a curved solid surface as it propagates. Refraction is the turning of the direction of propagation of a duct mode by mean flow gradients. Parametric studies on the changes in the directivity of radiated sound due to variations in forward flight Mach number, duct mode frequency, azimuthal mode number and radial mode number are carried out. It is found there is a significant difference in directivity for the radiation of the same duct mode from an engine inlet when operating in static condition versus one in forward flight. It will be shown that the large change in directivity is the result of the combined effects of diffraction and refraction.
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Pečinka, Jiří, Gabriel Thomas Bugajski, Petr Kmoch, and Adolf Jílek. "JET ENGINE INLET DISTORTION SCREEN AND DESCRIPTOR EVALUATION." Acta Polytechnica 57, no. 1 (February 28, 2017): 22–31. http://dx.doi.org/10.14311/ap.2017.57.0022.
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Total pressure distortion is one of the three basic flow distortions (total pressure, total temperature and swirl distortion) that might appear at the inlet of a gas turbine engine (GTE) during operation. Different numerical parameters are used for assessing the total pressure distortion intensity and extent. These summary descriptors are based on the distribution of total pressure in the aerodynamic interface plane. There are two descriptors largely spread around the world, however, three or four others are still in use and can be found in current references. The staff at the University of Defence decided to compare the most common descriptors using basic flow distortion patterns in order to select the most appropriate descriptor for future department research. The most common descriptors were identified based on their prevalence in widely accessible publications. The construction and use of these descriptors are reviewed in the paper. Subsequently, they are applied to radial, angular, and combined distortion patterns of different intensities and with varied mass flow rates. The tests were performed on a specially designed test bench using an electrically driven standalone industrial centrifugal compressor, sucking air through the inlet of a TJ100 small turbojet engine. Distortion screens were placed into the inlet channel to create the desired total pressure distortions. Of the three basic distortions, only the total pressure distortion descriptors were evaluated. However, both total and static pressures were collected using a multi probe rotational measurement system.
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Zhao, Xue Jun, Xiao Guo Guo, and Chang Zhao. "A New Support Structure in Waverider Force Measurement." Applied Mechanics and Materials 318 (May 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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Bazazzadeh, Mehrdad, and Ali Shahriari. "Enhancing the Performance of Jet Engine Fuel Controller Using Neural Networks." Applied Mechanics and Materials 390 (August 2013): 393–97. http://dx.doi.org/10.4028/www.scientific.net/amm.390.393.
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This paper proposes a fuzzy logic controller for a specific turbojet engine. The turbine engines require control systems to achieve the appropriate performance. The control systems typically featured loops to prevent engine flame out, over speeds, compressor surge, and check turbine inlet temperature limit, either by scheduling the fuel flow during accelerations and decelerations or by controlling the acceleration and deceleration rates of engine spool. This paper presents a successful approach in designing a Fuzzy Logic Controller for a specific Jet Engine. At first a suitable mathematical model for the jet engine is presented by the aid of SIMULINK simulation software. Then by applying different reasonable fuel flow functions via the engine model, some important engine continuous time operation parameters (such as: thrust, compressor surge margin, turbine inlet temperature and engine spool speed...) are obtained. These parameters provide a precious database which can be used by a neural network. At the second step, by designing and training a feedforward multilayer perceptron neural network according to this available database; a number of different reasonable fuel flow functions for various engine acceleration operations are determined. These functions are used to define the desired fuzzy fuel functions. Indeed, the neural networks are used as an effective method to define the optimum fuzzy fuel functions. At the next step we design a fuzzy logic controller by using the engine simulation model and the neural network results. The proposed control scheme is proved by computer simulation using the designed engine model. The simulation results of engine model with fuzzy controller in comparison with the engine testing operation illustrate that the proposed controller achieves the desired performance.
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Catana, Razvan Marius, and Grigore Cican. "Study of Air Excess in Relation with Engine Parameters for a Generalized Reaction Based on JET-A Fuel." Applied Mechanics and Materials 772 (July 2015): 395–400. http://dx.doi.org/10.4028/www.scientific.net/amm.772.395.
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In this paperwork we are studying the performance of a combustion process into a jet engine combustion chamber, more specifically the relations between excess of air, overall pressure ratio and inlet turbine temperature for a combustion reaction based on a jet A fuel. The study present a method of calculating the excess of air for a generalized combustion reaction based on Jet A fuel indicated by the general formula , for different temperatures of air, different temperatures of fuel and different inlet turbine temperatures. The result of this study is to achieve diagrams in which are presented the variation of air excess with engine parameters who participate in combustion process and to performed a computing program in which it is calculated the exactly value of excess of air for any outlet compressor temperatures, any inlet turbine temperatures and different fuel temperatures.
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Fukuda, Masafumi, Hiroshi Harada, Tadaharu Yokokawa, and Tomonori Kitashima. "Virtual Jet Engine System." Materials Science Forum 638-642 (January 2010): 2239–44. http://dx.doi.org/10.4028/www.scientific.net/msf.638-642.2239.
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In 1999, we proposed the concept of a virtual gas turbine system which is a combination of turbine design and material design programs. Using this system, it has become possible to design a gas turbine engine and a combined cycle automatically, by inputting some basic information such as power output, turbine inlet temperature and material specifications. The derived outputs are turbine gas path dimensions, gas and cooling air flow rates, thermal efficiency, CO2 emissions, etc. We use the system to evaluate the potential improvement if a newly developed material is to be used in building the engine. Based on the virtual gas turbine system we have begun developing the virtual jet engine system, which can simulate the operation of a jet engine or a gas turbine engine to predict the degradation of materials used in the high temperature parts of the engine. The system consists of a thermal and aerodynamic analysis of the engine, a thermal and stress analysis of hot parts, and a material degradation analysis. Actual engine dimensions, operation data and material specifications are used to perform the analyses. In this paper, we will show some of the results of the use of the virtual gas turbine system, and then describe the development plan and the preliminary output of the virtual jet engine system.
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SKRZEK, Tomasz. "Duel fuel compression ignition engine fuelled with homogeneous mixtures of propane and kerosene-based fuel." Combustion Engines 178, no. 3 (July 1, 2019): 191–97. http://dx.doi.org/10.19206/ce-2019-333.
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The paper presents some results of examination of DF CI engine fuelled with kerosene-based fuel (Jet A-1) and propane. The aim was to obtain the maximum engine thermal and overall efficiency and checking the engine emissions for the application of significant share of propane as a main source of energy. The fuel which initiates the ignition was Jet A-1 provided by common rail system during the beginning of compression stroke. Propane was provided to inlet manifold in a gas phase. The method of providing of both fuels to the engine cylinder allowed to create nearly homogeneous mixture and realized HCCI process for dual fueling with Jet A-1 and propane. It was possible to compare two combustion strategies PCCI and HCCI for fuelling of CI engine with single fuel (Jet A-1) and dual fuelling with Jet A-1 and propane. The results of experiment show that the NOx and soot emissions are much lower than for standard CI or SI engines. The results also show very interesting potential role of propane in control of HCCI dual fuel combustion process which gives the new perspective of dual fuel engine development. The low levels of toxic components in exhaust gases encourage to test and develop this type of fuelling which could radically confine the negative influence on the environment as well as enable to apply an alternative fuels.
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Al-Khalil, Kamel M., Theo G. Keith, and Kenneth J. De Witt. "Icing Calculations on a Typical Commercial Jet Engine Inlet Nacelle." Journal of Aircraft 34, no. 1 (January 1997): 87–93. http://dx.doi.org/10.2514/2.2139.
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Ross, D. C., J. L. Volakis, and H. T. Anastassiu. "Hybrid finite element-modal analysis of jet engine inlet scattering." IEEE Transactions on Antennas and Propagation 43, no. 3 (March 1995): 277–85. http://dx.doi.org/10.1109/8.371997.
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Knyshenko, Yu V., and V. M. Durachenko. "Mathematical model of the operation of a different-scale two-component low-thrust jet engine system." Technical mechanics 2022, no. 3 (October 3, 2022): 47–62. http://dx.doi.org/10.15407/itm2022.03.047.
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The aim of this work is to modify a comprehensive mathematical model of a system of two-component low-thrust jet engines using the numerical method of characteristics in the propellant pipeline system with account for different sound speeds in the oxidizer and the fuel employing a unified method of pipeline discretization. This paper presents a unified approach to a numerical implementation of the method of characteristics for both fuel components and for regular computational cross-sections (internal for structural sections with constant geometrical and elastic parameters) and terminal cross-sections at the pipeline system inlets, the section joints, and the engine inlets for each propellant components. The approach accounts for the hydraulic resistances of the propellant injectors and electric propellant valves and the actual pressures in the engine combustion chambers. The performance of the mathematical model is illustrated by the example of the predesigning of a system of different-scale low-thrust engines to control the motion of a spacecraft relative to its center of mass in pitch, yaw, and roll and transfer the spacecraft to a new orbit (higher of lower) for maneuvering and docking with another spacecraft. The computed results show the possibility of determining the key hydraulic and gas-dynamic parameters of the system in transient conditions: the pressure and propellant component flow rate distribution at the inlet of any of the engines, the combustion chamber pressure and thrust characteristics of each engine, and the mutual effect of the engines on their thrust characteristics by the example of varying the flow areas of the propellant manifolds in the steady (continuous) and unsteady pulsed operation of all engines or some of them. The proposed mathematical model may be used in the computational justification of design parameters and operating conditions in the preparation of a draft proposal or in the predesign determination of an engine system configuration. Detailed information on the hydraulic and gas-dynamic performance parameters of an engine system is an important complement to the results of a ground tryout of both single engines and an engine system in conditions that simulate the flight environment.
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Tabakoff, W. "Compressor Erosion and Performance Deterioration." Journal of Fluids Engineering 109, no. 3 (September 1, 1987): 297–306. http://dx.doi.org/10.1115/1.3242664.
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Aircraft engines operating in areas where the atmosphere is polluted by small solid particles are typical examples of jet engines operating under hostile atmospheric environment. The particles may be different kinds of sand, volcanic ashes or others. Under these conditions, the gas and particles experience different degrees of turning as they flow through the engine. This is mainly due to the difference in their inertia. This paper presents the results of an investigation of the solid particle dynamics through a helicopter engine with inlet particle separator. The particle trajectories are computed in the inlet separator which is characterized by considerable hub and tip contouring and radial variation in the swirling vane shape. The nonseparated particle trajectories are determined through the deswirling vanes and the five stage axial flow compressor. The results from this study include the frequency of particle impacts and the erosion distribution on the blade surfaces.
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Pazur, W., and L. Fottner. "The Influence of Inlet Swirl Distortions on the Performance of a Jet Propulsion Two-Stage Axial Compressor." Journal of Turbomachinery 113, no. 2 (April 1, 1991): 233–40. http://dx.doi.org/10.1115/1.2929091.
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Aeroengine intakes containing S-shaped diffusers produce different types of inlet swirl distortions and essentially a combination of a twin swirl and a bulk swirl. The main object of this investigation was to assess the influence of inlet swirl distortions on the performance of a transonic two-stage axial compressor installed in a turbo jet bypass engine Larzac 04. A typical inlet swirl distortion was simulated by a delta-wing in front of the engine. An experimental method was investigated to measure the performance map of the installed low-pressure compressor for different engine operating lines. The influence of an inlet swirl distortion with different strengths on the performance map of the compressor was investigated experimentally. It is shown that the performance parameters decrease and a temperature distortion is generated behind the compressor. As the basis of the theoretical investigations of the performance map, including inlet swirl distortions, a computing model considering four compressors working in parallel was established. The model is based on the idea that an inlet swirl distortion can be substituted by two fundamental types of swirl components, i.e., a bulk swirl corotating, and a bulk swirl counterrotating to the revolution of the compressor. Computed performance maps of the compressor will be discussed and compared with the experimental data.
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Langston, Lee S. "Gems of Turbine Efficiency." Mechanical Engineering 136, no. 09 (September 1, 2014): 76–77. http://dx.doi.org/10.1115/9.2014-sep-9.
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This article discusses the use of turbine single-crystal blades in gas turbines. Single-crystal turbine blades were first used in military engines on Pratt’s F100 engine, which powered the F16 and F15 fighter aircrafts. Their first commercial use was on P&WA’s JT9D-7R4 engine, which received FAA certification in 1982, powering Boeing’s 767 and the Airbus A310. In jet engines, single-crystal turbine airfoils have proven to have as much as nine times more relative life in terms of creep strength and thermal fatigue resistance and over three times more relative life for corrosion resistance, when compared to equiaxed crystal counterparts. Modern high turbine inlet temperature jet engines with long life would not be possible without the use of single-crystal turbine airfoils. By eliminating grain boundaries, single-crystal airfoils have longer thermal and fatigue life, are more corrosion resistant, can be cast with thinner walls, and have a higher melting temperature. These improvements all contribute to higher gas turbine thermal efficiencies.
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Skachkov, S. V., and D. D. Shpakovskiy. "Numerical simulation of gas flow in jet nozzle." Journal of «Almaz – Antey» Air and Space Defence Corporation, no. 3 (September 30, 2016): 41–46. http://dx.doi.org/10.38013/2542-0542-2016-3-41-46.
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We determined traction and hydraulic characteristics of the jet nozzle of a gas turbine engine, taking into account the geometry of the internal structural elements and flow swirl in the inlet section according to the results of numerical simulation.
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Pajkovic, Vladimir, and Stojan Petrovic. "Spatial flow velocity distribution around an inlet port/valve annulus." Thermal Science 12, no. 1 (2008): 73–83. http://dx.doi.org/10.2298/tsci0801073p.
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An experimental investigation of the airflow through inlet port of a standard production direct injection diesel engine is presented. The investigation comprises mass flow rate and pressure drop measurements at fixed valve lifts, and spatial distributions of mean and r.m.s. velocity components around the port/valve annulus measured under steady flow conditions by special designed miniature hot-wire anemometer X probe. The results show that the velocity field is distributed non-uniformly across the valve gap and around valve periphery. Nonuniformity is more expressed at higher valve lifts. Flow instability in a jet leaving the port (jet flapping) is also evident since the skewness and kurtosis of the velocity probability distribution function depart from the Gaussian form. The presented experimental method, based on the application of miniature multiple hot-wire probes, makes possible investigation of flow performances of an inlet port and poppet valve assembly of a production engine head without any modification for ensuring an optical access within the port/cylinder.
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Ross, D. C., J. L. Volakis, and H. T. Anastassiu. "Overlapping modal and geometric symmetries for computing jet-engine inlet scattering." IEEE Transactions on Antennas and Propagation 43, no. 10 (1995): 1159–63. http://dx.doi.org/10.1109/8.467656.
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Shen, Bin Xian, and Wei Qiang Liu. "Analysis of the Fluid Diffusion Characteristics in Platelet Pre-Mixer." Defect and Diffusion Forum 370 (January 2017): 98–102. http://dx.doi.org/10.4028/www.scientific.net/ddf.370.98.
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Platelet mixer is a type of high-efficient equipment which can mix fluids through platelet micro-channels by cross-bedded injection. It overcomes disadvantages that the fluid is centralized around the inlet and it improves the diffusion. In this work, the platelet mixer is used for pre-mixer in a rocket engine, and the diffusion of oxygen and air in pre-mixer is analyzed. The high speed jet leads to a strong shear force near the inlet which produces counter-rotating stream-wise vortices around the jet. The angle between the direction of jet and radial direction influences both the stream-wise vortices and diffusion. The vortices intensity increases as the angle increase from 0o to 20o.
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Gao, Yuhang, and Jian Zheng. "Noise simulation of wake field of solid rocket motor." Journal of Physics: Conference Series 2364, no. 1 (November 1, 2022): 012004. http://dx.doi.org/10.1088/1742-6596/2364/1/012004.
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Abstract When the rocket engine works, it will produce high-temperature and high-speed gas, which will be rapidly mixed with the surrounding medium, and will produce huge jet noise. This paper studies jet flow field and sound field of rocket engine using Fluent. The broadband noise simulation shows that the noise distribution is related to the nozzle jet. The sound pressure data of transient FW-H observation points show that the noise frequency distribution is wide. At the same time, the size of the noise will increase with the increase of the inlet pressure, and the influence range will become larger with the increase of area expansion ratio.
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Liu, Zhan Xin, Si Wei Wang, and Ping Gao. "Simulation of Sound Wave Propagation at the Inlet of a Jet Engine." Applied Mechanics and Materials 52-54 (March 2011): 500–503. http://dx.doi.org/10.4028/www.scientific.net/amm.52-54.500.
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Simulation of sound wave propagation at the inlet of a jet engine is difficult due to the complex geometries of the propagation channel, so many simplifications are needed. A more realistic model is introduced in this paper to do the simulation. Dispersion-relation-preserving finite schemes are used in this paper where structured grids are designed by conformal mapping; the advanced perfectly matched layer absorbing boundary conditions are used to prescribe the input sound wave at the fan face of inlet. The advantages of the methods used in this paper are shown by two different cases.
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Timoshenko, V. I., V. P. Halynskyi, and Yu V. Knyshenko. "Theoretical studies on rocket/space hardware aerogas dynamics." Technical mechanics 2021, no. 2 (June 29, 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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Ezrokhi, Yu A., and E. A. Khoreva. "Assessing the Impact of the Inlet Total Pressure Distortion on the Turbofan Thrust." Mechanical Engineering and Computer Science, no. 1 (March 3, 2018): 19–30. http://dx.doi.org/10.24108/0118.0001360.
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The paper considers techniques to develop a mathematical model using a method of «parallel compressors». The model is intended to estimate the impact of the air inlet distortion on the primary parameters of the aero-engine. The paper presents rated estimation results in the context of twin spool turbofan design for two typical cruiser modes of flight of the supersonic passenger jet. In estimation the base values σbase and the average values of the inlet ram recovery σave remained invariable. Thus, parametrical calculations were performed for each chosen relative value of the area of low-pressure region.The paper shows that an impact degree of the inlet distortion on the engine thrust for two modes under consideration is essentially different. In other words, if in the subsonic mode the impact assessment can be confined only to taking into account the influence of decreasing average values of the inlet total pressure, the use of such an assumption in the supersonic cruiser mode may result in considerable errors.With invariable values of the pressure recovery factor at the engine intake, which correspond to the speed of flight for a typical air inlet of external compression σbase, and average value σave, a parameter Δσuneven has the main effect on the engine thrust, and degree of this effect essentially depends on a difference between σave and σbase values.
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Laube, Tomasz, and Janusz Piechna. "Analytical and Numerical Feasibility Analysis of a Contra-Rotary Ramjet Engine." Energies 13, no. 1 (December 30, 2019): 163. http://dx.doi.org/10.3390/en13010163.
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A new idea for a contra-rotary ramjet engine is presented. To define the theoretical limits of the non-typical, contra-rotary ramjet engine configuration, its analytical model was developed. The results obtained from that model and the analytical results were compared with those received from numerical simulations. The main weakness of existing rotary ramjet engine projects is the very high rotational speed of the rotor required for achieving supersonic inlet flow. In this paper, a new idea for a contra-rotary ramjet engine (CORRE) is presented and analyzed. This paper presents the results of analytical analysis and numerical simulations of a jet engine system with two rotors rotating in opposite directions. Contra-rotating rotors generate a supersonic air velocity at the inlet to the compressor at two times slower rotor’s speed. To determine the flow characteristics, combustion process, and engine efficiency of the double-rotor engine, a numerical solution of the average Navier-Stokes equations was used with the k-eps turbulence model and the non-premixed combustion model. The results of numerical simulations of flow and the combustion process inside the contra-rotary jet engine achieving a shockwave compression are shown and compared with similar data for a single-rotor engine design and analytical data. This paper presents only the calculation results of the flow processes and the combustion process, indicating the advantages of the proposed double-rotor design. The results of the numerical analysis were presented on the contours and diagrams of the pressure and flow velocity, temperature distribution, and mass fraction of the fuel.
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Doubrava, Radek, Martin Oberthor, Petr Bělský, and Jan Raška. "Bird and hail stone impact resistance analysis on a jet engine composite air inlet." MATEC Web of Conferences 188 (2018): 04006. http://dx.doi.org/10.1051/matecconf/201818804006.
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Bird or hail stone impacts are an important phenomenon that must be taken into consideration when designing aircraft. As engines are the sole thrust-providing mechanisms of an aircraft, it is critical that the effects of bird or hail stone strikes on engine inlets and systems be investigated and mitigated to the greatest extent possible. A combination of experiments and numerical simulations is necessary to properly understand the behaviour of a bird or hail stone during impact and the reaction of the impacted material with the structure. A simulation methodology is developed and validated to certify the bird or hail stone strike resistance of composite air ducts designed for a new generation of jet training aircraft. Physical impact tests were performed on real composite parts. Numerical simulation results were compared with test results. Numerical simulation was also used for test preparation and optimization of the test rig design from the point of view of the influence of the stiffness of the surrounding aircraft structure. The validated modelling procedure allows the analysis of numerous impact scenarios, improving the optimization procedures for aircraft component design and reducing the cost of development by reducing the need to manufacture test prototypes.
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Klein, A. "The relation between losses and entry-flow conditions in short dump diffusers for combustors." Aeronautical Journal 92, no. 920 (December 1988): 390–96. http://dx.doi.org/10.1017/s0001924000016523.
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SummaryAn experimental correlation is presented between the losses and the inlet flow conditions in short dump diffusers for turbojet combustors. Cascades of compressor blades upstream of the diffuser were used to make the flow field at inlet similar to that in a real jet engine. The flow field was altered in two ways — by varying the distance between the cascades and the diffuser inlet plane and by changing the blade aspect ratio. The measurements show clearly that distortions in the radial direction affect the losses to a much larger extent than non-uniformities in the circumferential direction. In consequence, the performance can be correlated to a satisfactory degree of accuracy simply by using the radial blockage factor at inlet.
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Steele, R. C., A. C. Jarrett, P. C. Malte, J. H. Tonouchi, and D. G. Nicol. "Variables Affecting NOx Formation in Lean-Premixed Combustion." Journal of Engineering for Gas Turbines and Power 119, no. 1 (January 1, 1997): 102–7. http://dx.doi.org/10.1115/1.2815532.
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The formation of NOx in lean-premixed, high-intensity combustion is examined as a function of several of the relevant variables. The variables are the combustion temperature and pressure, fuel type, combustion zone residence time, mixture inlet temperature, reactor surface-to-volume ratio, and inlet jet size. The effects of these variables are examined by using jet-stirred reactors and chemical reactor modeling. The atmospheric pressure experiments have been completed and are fully reported. The results cover the combustion temperature range (measured) of 1500 to 1850 K, and include the following four fuels: methane, ethylene, propane, and carbon monoxide/hydrogen mixtures. The reactor residence time is varied from 1.7 to 7.4 ms, with most of the work done at 3.5 ms. The mixture inlet temperature is taken as 300 and 600 K, and two inlet jet sizes are used. Elevated pressure experiments are reported for pressures up to 7.1 atm for methane combustion at 4.0 ms with a mixture inlet temperature of 300 K. Experimental results are compared to chemical reactor modeling. This is accomplished by using a detailed chemical kinetic mechanism in a chemical reactor model, consisting of a perfectly stirred reactor (PSR) followed by a plug flow reactor (PFR). The methane results are also compared to several laboratory-scale and industrial-scale burners operated at simulated gas turbine engine conditions.
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Doubrava, Radek, Martin Oberthor, Petr Bělský, and Jan Raška. "High-speed impact assessment for composite air inlet." International Journal of Structural Integrity 11, no. 5 (October 31, 2019): 723–36. http://dx.doi.org/10.1108/ijsi-10-2018-0059.
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Purpose The purpose of this paper is to describe the approach for the design of a jet engine composite air inlet for a new generation of jet trainer aircraft from the perspective of airworthiness requirements regarding high-speed impact resistance. Design/methodology/approach Validated numerical simulation was applied to flat test panels. The final design was optimised and verified by validated numerical simulation and verified by testing on a full-scale demonstrator. High-speed camera measurement and non-destructive testing (NDT) results were used for the verification of the numerical models. Findings The test results of flat test panels confirmed the high durability of the composite structure during inclined high-speed impact with a near-real jet inlet load boundary condition. Research limitations/implications Owing to the sensitivity of the composite material on technology production, the results are limited by the material used and the production technology. Practical implications The application of flat test panels for the verification and tuning of numerical models allows optimised final design of the air inlet and reduces the risk of structural non-compliance during verification tests. Originality/value Numerical models were verified for simulation of the real composite structure based on high-speed camera results and NDT inspection after impact. The proposed numerical model was simplified for application in a real complex design and reduced calculation time.
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Colban, W., A. Gratton, K. A. Thole, and M. Haendler. "Heat Transfer and Film-Cooling Measurements on a Stator Vane With Fan-Shaped Cooling Holes." Journal of Turbomachinery 128, no. 1 (February 1, 2005): 53–61. http://dx.doi.org/10.1115/1.2098789.
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In a typical gas turbine engine, the gas exiting the combustor is significantly hotter than the melting temperature of the turbine components. The highest temperatures in an engine are typically seen by the turbine inlet guide vanes. One method used to cool the inlet guide vanes is film cooling, which involves bleeding comparatively low-temperature, high-pressure air from the compressor and injecting it through an array of discrete holes on the vane surface. To predict the vane surface temperatures in the engine, it is necessary to measure the heat transfer coefficient and adiabatic film-cooling effectiveness on the vane surface. This study presents heat transfer coefficients and adiabatic effectiveness levels measured in a scaled-up, two-passage cascade with a contoured endwall. Heat transfer measurements indicated that the behavior of the boundary layer transition along the suction side of the vane showed sensitivity to the location of film-cooling injection, which was simulated through the use of a trip wire placed on the vane surface. Single-row adiabatic effectiveness measurements without any upstream blowing showed jet lift-off was prevalent along the suction side of the airfoil. Single-row adiabatic effectiveness measurements on the pressure side, also without upstream showerhead blowing, indicated jet lifted-off and then reattached to the surface in the concave region of the vane. In the presence of upstream showerhead blowing, the jet lift-off for the first pressure side row was reduced, increasing adiabatic effectiveness levels.
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Shaw, C. T., D. J. Lee, S. H. Richardson, and S. Pierson. "Measuring the flow through a model engine inlet system containing a plenum and runners." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 215, no. 8 (August 1, 2001): 955–64. http://dx.doi.org/10.1177/095440620121500808.
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This paper describes an experiment carried out in a model of an inlet system containing a plenum chamber and runners. Such inlet systems are commonly found on petrol internal combustion engines where the cylinders are arranged in a V-configuration. Measurements of velocity, turbulence intensity and pressure drop across the system have been made and a detailed error analysis carried out. These measurements are suitable for the validation of results obtained from computational fluid dynamics (CFD) software. Particular attention has been paid to reducing turbulence intensity levels at the inlet of the system, with additional entry lengths and smooth bell-mouth profiles being used. At each measurement point the laser Doppler anemometry (LDA) system has been tuned by hand to improve measurement sensitivity. Seeding of the flow has been an important factor and water droplets produced by a medical nebulizer have been used. Errors in velocity measurement vary throughout the flowfield, with a strong dependency on turbulence levels. From the results a relatively simple three-dimensional flow structure is found with the inlet flow separating on entry to the plenum, forming a ring vortex with a central jet within it. This jet turns from the horizontal to the vertical to enter the open runner, forming a separation bubble on the upstream side of the runner. A large slow-moving recirculation region forms in the plenum downstream of the open runner. From measurements of turbulence intensities, large values of around 40 per cent are found at the plenum-runner interface and in the recirculation region. This means that the flow is essentially time dependent even for notionally steady state conditions.
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Bazazzadeh, M., H. Badihi, and A. Shahriari. "Gas Turbine Engine Control Design Using Fuzzy Logic and Neural Networks." International Journal of Aerospace Engineering 2011 (2011): 1–12. http://dx.doi.org/10.1155/2011/156796.
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This paper presents a successful approach in designing a Fuzzy Logic Controller (FLC) for a specific Jet Engine. At first, a suitable mathematical model for the jet engine is presented by the aid of SIMULINK. Then by applying different reasonable fuel flow functions via the engine model, some important engine-transient operation parameters (such as thrust, compressor surge margin, turbine inlet temperature, etc.) are obtained. These parameters provide a precious database, which train a neural network. At the second step, by designing and training a feedforward multilayer perceptron neural network according to this available database; a number of different reasonable fuel flow functions for various engine acceleration operations are determined. These functions are used to define the desired fuzzy fuel functions. Indeed, the neural networks are used as an effective method to define the optimum fuzzy fuel functions. At the next step, we propose a FLC by using the engine simulation model and the neural network results. The proposed control scheme is proved by computer simulation using the designed engine model. The simulation results of engine model with FLC illustrate that the proposed controller achieves the desired performance and stability.
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Parrish, Sarah, and Christopher Tam. "Investigation of noise radiation from a jet engine inlet by direct numerical simulation." Journal of the Acoustical Society of America 131, no. 4 (April 2012): 3429. http://dx.doi.org/10.1121/1.4708861.
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Langston, Lee S. "Fahrenheit 3,600." Mechanical Engineering 129, no. 04 (April 1, 2007): 34–37. http://dx.doi.org/10.1115/1.2007-apr-3.
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This article illustrates capabilities of gas turbines to be able to work in extremely elevated temperatures. The turbine airfoils in the new F135 jet engine that powers the Joint Strike Fighter (JSF) Lightning II are capable of operating at these extreme temperatures. The F135 gas turbine is the first production jet engine in this new 3,600°F class, designed to withstand these highest, record-breaking turbine inlet temperatures. The JSF engine is just one product in the $3.7 billion military gas turbine market, which includes jet engine production for the world’s fighter aircraft military cargo, transport, refuelling, and special-purpose aircraft. The article also discusses the features of H Class, which is the largest electric power gas turbine that has been interpreted as an abbreviation for humongous. Non-aviation gas turbines consist of electrical power generation, mechanical drive, and marine. The largest segment of that market by far is electrical power generation, in simple cycle, combined cycle, and cogeneration. Forecast International predicts significant growth in coming years in demand for gas turbine electrical power generation, rising from $8.6 billion in 2006 to a projected $13.5 billion in 2008, a 60 percent increase.
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Lee, Hsing-Juin, and Hsing-Wei Lee. "Deriving the Generalized Total Kinetic Power Equation for Jet Engine." Journal of Mechanics 14, no. 3 (September 1998): 145–52. http://dx.doi.org/10.1017/s1727719100000174.
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ABSTRACTIn light of incessant quest of better propulsion performance, it would be opportune to probe some propulsion insights for jet engine (JE) from a power point of view. In this study, we endeavor to prescribe logic reasoning process for obtaining the JE total kinetic power and prove its degenerated counterpart. With the Lagrangian Reynolds transport approach, we also rigorously derive the highly generalized equation for this power. Moreover, the validity, significance, and importance of this novel generalized power equation are delicately demonstrated by an interesting spring/mass model with known total kinetic power. Notably, the JE total kinetic power equations are quite reasonable physically speaking, since all the velocity quantities involved are of relative nature; otherwise, the JE total kinetic power may violate the energy conservation law under certain conditions. This total kinetic power produced by jet engine involves a few more physical effects including vehicle acceleration, relative flow velocity/steadiness, inlet/exit pressures, and gravity, thus open an original route for more efficient propulsion design.
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Yu, Jialei, Tiejun Liu, Tuliang Ma, and Chen Zhai. "Numerical Simulation Method with Engine Power and Analysis of Jet Interaction." Journal of Physics: Conference Series 2292, no. 1 (June 1, 2022): 012014. http://dx.doi.org/10.1088/1742-6596/2292/1/012014.
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Abstract To explore the effects of engine jet on overall aircraft aerodynamic performance, an aerodynamic numerical simulation method and the interference effects of aircraft with wing-mounted nacelle were studied. In aspect of numerical simulation, based on isentropic flow relationship and automatic mass-flow matching method, a high-precision / high-efficiency numerical simulation of inlet and exhaust boundary conditions is achieved. The calculation result is in good agreement with the experimental values, which validates the calculation method and boundary condition treatment. Through numerical simulation, it is found that the ejection of engine jet can accelerate the air flow, reduce the lower wing pressure, enhance the upper wing shock wave and increase the pitch down moment. At the same time, the effect of jet brings blowing drag and loses the cruise efficiency. The airflow acceleration caused by the narrow channel composed of engine, wing and pylon may cause strong aerodynamic interference. It can be effectively weakened by adjusting the pylon contraction shape based on the near-field pressure distribution. In this way, the shock in the inner side of the pylon can also be eliminated.
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Sing Mei, Sim, Aslina Anjang Ab Rahman, Mohd Shukur Zainol Abidin, and Nurul Musfirah Mazlan. "d2 Law and Penetration Length of Jatropha and Camelina Bio-Synthetic Paraffinic Kerosene Spray Characteristics at Take-Off, Top of Climb and Cruise." Aerospace 8, no. 9 (September 4, 2021): 249. http://dx.doi.org/10.3390/aerospace8090249.
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A comparison of d2 law and penetration length of biofuels with Jet–A through the incorporation of fuel properties and actual combustor inlet data at various flight trajectories is presented. This study aims to identify fuel properties and flight operating conditions that most influence droplet characteristics accurately. The study comprises two phases involving a simulation using GSP to predict combustor inlet data for the respective flight operating conditions and a simulation using ANSYS Fluent V18.1 to obtain combustion characteristics of biofuels and Jet–A. The biofuels chosen in this study are Jatropha Bio-synthetic Paraffinic Kerosene (JSPK) and Camelina Bio-synthetic Paraffinic Kerosene (CSPK), evaluated as pure (100%) and blend (50%) with Jet–A. Thrust specific fuel consumption (TSFC) of biofuels is improved due to lower fuel consumed by the engine. The d2 law curve shows a heat-up period that takes place at the early stage of the combustion process. The penetration length of the fuels is shorter at take-off. Combusting biofuels reduce combustion temperature and the penetration length of the droplet.
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Syverud, Elisabet, and Lars E. Bakken. "Online Water Wash Tests of GE J85-13." Journal of Turbomachinery 129, no. 1 (January 1, 2007): 136–42. http://dx.doi.org/10.1115/1.2372768.
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This paper reports the results of a series of online water wash tests of a GE J85-13 jet engine at the test facilities of the Royal Norwegian Air Force. The engine performance was deteriorated by injecting atomized saltwater at the engine inlet. The engine was then online washed with water injected at three different droplet sizes (25, 75, and 200μm) and at water-to-air ratios ranging from 0.4% to 3% by mass. Engine performance was measured using standard on-engine instrumentation. Extra temperature and pressure sensors in the compressor section provided additional information of the propagation of deposits in the aft stages. The measurements were supported by visual observations. The overall engine performance improved rapidly with online wash. The buildup of deposits in the aft stages was influenced both by the droplet size and the water-to-air ratio. The water-to-air ratio was the most important parameter to achieve effective online washing.
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Yadav, Krishnakumar Rajnath, Akshoy Ranjan Paul, Nithin Hegde, and Anuj Jain. "A Comparison of Circular and Slotted Synthetic Jets for Flow Control in a Twin Air Intake." Defence Science Journal 70, no. 2 (March 9, 2020): 113–21. http://dx.doi.org/10.14429/dsj.70.13053.
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The performance of an aircraft engine depends on air flow quality at the engine face / the exit of the air-intake also known as aerodynamic inlet plane (AIP). A single-engine aircraft has complex Y-shaped twin air-intake which causes severe flow separation, distortion and flow non-uniformity at the AIP. The present study compares the efficacy of slotted synthetic jet and a row of four circular synthetic jets attached to inner faces of a twin air-intake to improve aerodynamic performance at the AIP. The results are obtained using computational fluid dynamics. The velocity and vorticity plots show that lateral spread of the circular jets is limited as compared to the slotted jet. The circular jets are found to be weak as compared to slotted jet to prevent separation of main flow occurring in the twin air-intake. The various aerodynamic performance parameters, such as static pressure recovery coefficient, total pressure loss coefficient, distortion coefficient and secondary flow uniformity are compared for both the cases, exhibiting marked improvement in all these parameters. The study demonstrates that the slotted synthetic jets is a better option for controlling flow in twin air-intake as compared to a row of circular synthetic jets.
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Reksowardojo, Iman K., Long H. Duong, Rais Zain, Firman Hartono, Septhian Marno, Wawan Rustyawan, Nelliza Putri, Wisasurya Jatiwiramurti, and Bayu Prabowo. "Performance and Exhaust Emissions of a Gas-Turbine Engine Fueled with Biojet/Jet A-1 Blends for the Development of Aviation Biofuel in Tropical Regions." Energies 13, no. 24 (December 13, 2020): 6570. http://dx.doi.org/10.3390/en13246570.
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Biofuels as alternative fuels in today’s world are becoming increasingly important for the reduction of greenhouse gases. Here, we present and evaluate the potential of a new alternative fuel based on the conversion of medium-chain fatty acids to biojet (MBJ), which was produced from coconut oil using hydrotreated processes. MBJ is produced by using both deoxygenation and isomerization processes. Several blends of this type of biojet fuel with Jet A-1 were run in a gas-turbine engine (Rover 1S/60, ROTAX LTD., London, England) for the purpose of investigating engine performance and emissions. Performance results showed almost the same results as those of Jet A-1 fuel for these fuels in terms of thermal efficiency, brake-specific fuel consumption, turbine-inlet temperature, and exhaust-gas temperature. The results of exhaust-gas emissions also showed no significant effects on carbon monoxide, unburned hydrocarbon, and nitrogen oxides, while a decrease in smoke opacity was found when blending MBJ with Jet A-1. MBJ performed well in both performance and emissions tests when run in this engine. Thus, MBJ brings hope for the development of aviation biofuels in tropical regions that have an abundance of bioresources, but are limited in technology and investment capital.
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Kovalchuk, O., O. Skorohvatov, A. Galkin, L. Gordishevski, and V. Liskovchuk. "ARMORED SHELLS WITH STRAIGHT AIR JET ENGINE." Collection of scientific works of Odesa Military Academy 1, no. 13 (December 30, 2020): 34–43. http://dx.doi.org/10.37129/2313-7509.2020.13.1.34-43.
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The article analyzes the problems of sub-caliber feathered projectile, offers a variant of equipping such a projectile with an air-jet engine, graphs of air resistance, calculations of the required thrust of the air-jet engine. Features of armor-piercing projectiles with a direct-flow air-jet engine are considered, the main calculations are performed using high-level Python programming language. Currently, as armor-piercing ammunition are widely used armor-piercing sub-caliber feathered shells (BPOS) with high penetrating ability This is achieved due to the high initial velocity of ammunition (1650-1840 m / s) and small cross section (d = 20-30 mm). To compensate for the force of air resistance, the provision of jet propulsion ammunition is used. But the main disadvantage of such shells is the dependence of the ability to pierce armor from a distance to the target. That is, due to the resistance of the air, the speed of the projectile is lost, namely its energy. What they are inferior to cumulative projectiles, for which the ability to pierce armor does not depend on the distance to the target. Modern armored vehicles have significant armor and BPOS lose their importance in the range of cumulative projectiles and anti-RPG. This situation can be corrected if the BPOS is equipped with direct-flow jet engines (PPD). Direct-flow air jet engine (PPD), simple in design, has a high efficiency at large Mach numbers, compact, because it does not require the presence of an oxidant in the fuel, as it uses oxygen from the environment. Compressed air entering the combustion chamber from the inlet device is heated by oxidation of the fuel supplied to it. Created from a mixture of air with combustion products gas mixture – the working fluid in the nozzle reaches the speed of sound, and at its output expanding to supersonic. The working fluid flows at a speed greater than the speed of the oncoming air flow, which creates a jet thrust. When the flight speed is much less than the speed of the jet, the thrust increases. As the speed of flight approaches the speed of the jet, the thrust decreases, passing some maximum corresponding to the optimal speed of flight. With the development of mixed solid fuel technology, it began to be used in PPRD. A fuel checker with a longitudinal Central channel is placed in the combustion chamber. The working fluid passing through the combustion chamber oxidizes the fuel from its surface and heats up. The use of solid fuel further simplifies the design of the PPRD as it does not require a combustion chamber. The main part of the filler of mixed fuel PPRD is a fine powder of aluminum, magnesium or beryllium, the heat of combustion, which is much higher than the heat of combustion of hydrocarbon fuels. With the development of mixed solid fuel technology, it began to be used in PPRD. A fuel checker with a longitudinal Central channel is placed in the combustion chamber. The working fluid passing through the combustion chamber oxidizes the fuel from its surface and heats up. The use of solid fuel further simplifies the design of the PPRD as it does not require a combustion chamber. The main part of the filler of mixed fuel PPRD is a fine powder of aluminum, magnesium or beryllium, the heat of combustion, which is much higher than the heat of combustion of hydrocarbon fuels. An example of a solid propellant PPRD can be the propulsion engine of the anti-ship missile P-270 Mosquito. Depending on the speed of flight PPRD are divided into subsonic, supersonic and hypersonic. This division is due to the design features of each of these groups. In the supersonic range PPRD is much more effective than in the subsonic. For example, at a speed of M = 3, the degree of pressure increase in the PPRD is 37, which can be compared with the most high-pressure compressors of turbojet engines. Keywords: armor-piercing sub-caliber feathered projectile, air-jet engine, external ballistics.
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Hamstra, J. W., D. N. Miller, P. P. Truax, B. A. Anderson, and B. J. Wendt. "Active inlet flow control technology demonstration." Aeronautical Journal 104, no. 1040 (October 2000): 473–79. http://dx.doi.org/10.1017/s0001924000091971.
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Abstract This paper presents results from a joint Lockheed Martin/NASA Glenn effort to design and verify an ultra-compact, highly-survivable engine inlet subsonic duct based on the emerging technology of active inlet flow control (AIFC). In the AIFC concept, micro-scale actuation (∼mm in size) is used in an approach denoted ‘secondary flow control’ to intelligently alter a serpentine duct's inherent secondary flow characteristics with the goal of simultaneously improving the critical system-level performance metrics of total pressure recovery, spatial distortion, and RMS turbulence. In this approach, separation control is a secondary benefit, not a design requirement. The baseline concept for this study was a 4:1 aspect ratio ultra-compact (LID = 2·5) serpentine duct that fully obscured line-of-sight view of the engine face. At relevant flow conditions, this type of duct exhibits excessive pressure loss and distortion because of extreme wall curvature. Two sets of flow control effectors were designed with the intent of establishing high performance levels to the baseline duct. The first set used two arrays of 36 co-rotating microvane vortex generators (VGs); the second set used two arrays of 36 micro air-jet (microjet) VGs, which were designed to produce the same ‘vorticity signature’ as the microvanes. Optimisation of the microvane array was accomplished using a design of experiments (DOE) methodology to guide selection of parameters used in multiple Computational Fluid Dynamics (CFD) flow solutions. A verification test conducted in the NASA Glenn W1B test facility indicated low pressure recovery and high distortion for the baseline duct without flow control. With microvane flow control, at a throat Mach number of 0·60, pressure recovery was increased 5%, and both spatial distortion and turbulence were decreased approximately 50%. Microjet effectors also provided significantly improved performance over the baseline configuration.
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Heywood, John B. "Fluid Motion Within the Cylinder of Internal Combustion Engines—The 1986 Freeman Scholar Lecture." Journal of Fluids Engineering 109, no. 1 (March 1, 1987): 3–35. http://dx.doi.org/10.1115/1.3242612.
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The flow field within the cylinder of internal combustion engines is the most important factor controlling the combustion process. Thus it has a major impact on engine operation. This paper reviews those aspects of gas motion into, within, and out of the engine cylinder that govern the combustion characteristics and breathing capabilities of spark-ignition engines and compression-ignition or diesel engines. Necessary background information on reciprocating engine operating cycles, the primary effect of piston motion and the spark-ignition and diesel engine combustion processes is first summarized. Then the characteristics of flow through inlet and exhaust valves in four-stroke cycle engines, and through ports in the cylinder liner in two-stroke cycle engines are reviewed. These flows govern the airflow through the engine, and set up the in-cylinder flow that controls the subsequent combustion process. The essential features of common in-cylinder flows—the large scale rotating flows set up by the conical intake jet, the creation and development of swirl about the cylinder axis, the flows produced during compression due to combustion chamber shape called squish, flow during the combustion process, and two-stroke scavenging flows—are then described. The turbulence characteristics of these flows are then defined and discussed. Finally, flow phenomena which occur near the walls, which are important to heat transfer and hydrocarbon emissions phenomena, are reviewed. The primary emphasis is on developing insight regarding these important flow phemomena which occur within the cylinder. To this end, results from many different research techniques—experimental and computational, established and new—have been used as resources. It is the rapidly increasing convergence of engine flow information from these many sources that make this an exciting topic with promise of significant practical contributions.
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Du, Jun-min, Guang-hua Li, Ben-Shuai Fu, and Chuang You. "Numerical Simulation on Field Characteristics of the Horizontal Gas Jet Flow of Underwater Vehicle." Journal of Physics: Conference Series 2381, no. 1 (December 1, 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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Nur Shamimi Amirah Md Sunhazim, Fazila Mohd Zawawi, Ummikalsom Abidin, Syahrullail Samion, Kamarulafizam Ismail, and Ainaa Maya Munira Ismail. "CFD Investigation on The Jet-Engine Inspired Wind Turbine." CFD Letters 14, no. 2 (March 2, 2022): 72–80. http://dx.doi.org/10.37934/cfdl.4.2.7280.
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The Malaysian Government has set a more ambitious target to achieve higher penetration of Renewable Energy (RE) in the Malaysian energy mix which was 31% by 2025. Compared to the penetration of solar and wind power specifically in the European region, whose sharing was more than 50% of total generation, Malaysia currently only has 2% of its energy coming from RE generation sources, which mostly was provided by solar photovoltaic. In Malaysia’s energy sources point of view, wind RE-based power generation system was foreseen a promising potential provided the technology was suitably designed for low wind conditions. Therefore, the potentiality of the Jet-Engine inspired Wind Turbine operating under low-speed wind environment by mean of Computational Fluid Dynamics (CFD) numerical approach were explored in This study. The main objectives were to develop a reliable numerical model for accessing the capability of the Jet-Engine inspired Wind Turbine and to regulate its performance with influence of curly shroud on the induced flow. The conventional shrouded Wind Turbine has been modified which consist of a stator and a rotor blade covered by curly-shaped shroud adapting the concept of Jet-Engine. A constant wind speed of 5 m/s which was the average wind speed in Malaysia, and tip speed ratio (TSR) varies from 2 to 6 were specified in the simulation. The investigation discovered that the curly-shaped shroud gave an impact to the performance of the Wind Turbine as it can be reviewed from the comparison of the power coefficient on the Jet-Engine inspired Wind Turbine with shroud and without shroud. It was found that the shrouded Wind Turbine improved the power coefficient by 8.6% which was from 0.35 to 0.38. The effect of the curly shroud was also analysed by obtained the velocity and pressure contour from the ANSYS Fluent, where there was a swirl formation at the shroud as the air mixed at different angle, which causes the pressure drop and inlet velocity increased.
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Crunteanu, Daniel Eugeniu, Valentin Ionut Misirliu, Oana Dumitrescu, and Bogdan Gherman. "Influence of Exhaust Nozzle Geometry on the Jet Potential Core Development." Applied Mechanics and Materials 811 (November 2015): 145–51. http://dx.doi.org/10.4028/www.scientific.net/amm.811.145.
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In this paper, a numerical simulation was performed on a scale turbofan engine nozzle to asses the influence of two nozzle configurations over the flow performance while the nozzle is situated at a certain distance from the ground. The turbulence model chosen for this numerical simulation was SST k-ω to capture boundary layer detachment and jet attachment to the ground. For this analysis two different computational domains where considered, while for the third case, boundary conditions for secondary inlet where modified. To assess the impact of these geometry changes a comparison between cases is made at different location in the domain.
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Glover, Jennifer, and Dan O'Boy. "Acoustic space filling curve metamaterials for grazing flow in Jet engine inlets." INTER-NOISE and NOISE-CON Congress and Conference Proceedings 263, no. 6 (August 1, 2021): 394–406. http://dx.doi.org/10.3397/in-2021-1458.
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Acoustic metamaterials research has grown exponentially in the past 10 years driven by the advances in manufacturing and an increased understanding of damaging environment noise. 2020 was the first noise reduction target as set by Advisory Council for Aircraft Research and Innovation in Europe with a relative 50% decrease. This was missed by current Jet engine noise control technology; however, metamaterials offer an encouraging alternative. Space Filling Curves (SFC) have the potential to provide a lightweight, thin, high performance acoustic liner. SFC have a history in mathematical geometry dating back to the 1890's but are a comparatively new addition to acoustics. They are designed with a sub-wavelength curled cross-section creating a maze-like pattern which slows acoustic wave propagation through the liner enabling characteristics such as negative refraction and low frequency attenuation. This paper contains a comparison of some of the most promising SFC metamaterial acoustic liner designs, in terms of the fundamental theory of the design category and a discussion of the reflection, absorption and transmission characteristics in terms of a grazing flow conditions. Computer simulation and impedance tube based experimental testing compares the designs. The paper concludes with future application for aeroacoustics with particular focus on the engine inlet.
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Rajnath, Yadav K. K., Akshoy R. Paul, and Anuj Jain. "Flow Management in a Double-Offset, Transitional Twin Air-Intake at Different Inflow Conditions." Recent Patents on Mechanical Engineering 12, no. 2 (July 29, 2019): 168–79. http://dx.doi.org/10.2174/2212797612666190422145940.
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Background: Transitional twin air-intake is a vital component of the air-induction system of single-engine combat aircraft. Combat aircraft do not always fly at steady, uniform flow conditions. But in some cases, it operates at different asymmetric flow conditions, which cause a change in aerodynamic performance of aircraft components like compressor and combustor. Objective: In order to improve the air quality at the outlet of air-intake- called Aerodynamic Inlet Plane (AIP) of this twin air-intake and to improve its aerodynamic performance for wide ranges of inflow conditions, slotted synthetic jets are used. Methods: Computational studies are carried out using Computational Fluid Dynamics (CFD) software for various types of skewed turbulent velocity profiles at inlet-2 with skewness number (ξ = 0, 0.3, 0.5, 0.7), while an average uniform velocity of 20m/s at inlet-1. Based on this analysis, worst case is selected and a pair of slotted synthetic jets is used just before the inflexion plane of the twin air-intake using transition SST turbulence model. Results: The flow behaviour of transitional twin air-intake becomes more complex with the increase in skewness number, thereby decreasing the aerodynamic performance of the air-intakes. With the use of slotted synthetic jets, an improvement in static pressure recovery and decrement in total pressure loss coefficient, distortion in coeffient swirl coefficient and secondary flow non-uniformity are observed which is a great sign of improved aerodynamic performance for the twin air-intakes. Conclusion: It is proved in this study that synthetic jet can be used effectively in twin air-intake to control the flow features leading to better flow uniformity and increased overall performance at the AIP without increasing the net-mass flow rate, thereby reducing the chance of stall/surge in the aeroengines. Hybrid flow control technique (synthetic jet coupled with vortex generator array) or newer flow control technique (plasma jet) are being explored for its possible use in engine air-intakes as revealed from recent patents filed/published in this area.
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Kroeger, Jim. "Large and Small Turbofans." Mechanical Engineering 138, no. 09 (September 1, 2016): 80–82. http://dx.doi.org/10.1115/1.2016-sep-7.
Full textAbstract:
This article presents a study on common design challenges of large and small turbofans. Turbofan engines powering large transport aircraft have demonstrated much different design objectives than business-jet turbofans including thrust, range, mission type, development cost, unit price, maintainability standards, and production quantities. Prolific use of ‘thermal barrier coating’ has helped turbine designers compensate for the inability to distribute a large quantity of small diameter film holes over the turbine blade surface. The historical trends in overall pressure ratio observed for both large and small turbofans have parallel slopes. Small turbofans lag behind the larger engines due to the miniaturization required for low flowrates characteristic of the smaller engines. These trends are qualitatively demonstrated, showing the growth in both the overall engine pressure ratio and turbine inlet temperature for several decades. It has been noted in this paper that the importance of high-performance impeller designs and intricate turbine blade cooling concepts for very low compressor exit corrected flows has not yet been fully appreciated.