Download or read book Performance of a Hydrogen Burner to Simulate Air Entering Scramjet Combustors written by William Roger Russin and published by . This book was released on 1974 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt: Tests were conducted to determine the performance of a hydrogen burner used to produce a test gas that simulates air entering a scramjet combustor at various flight conditions. The test gas simulates air in that it duplicates the total temperature, total pressure, and the volume fraction of oxygen of air at flight conditions. The main objective of the tests was to determine the performance of the burner as a function of the effective exhaust port area. The conclusions were: (1) pressure oscillations of the chugging type were reduced in amplitude to plus or minus 2 percent of the mean pressure level by proper sizing of hydrogen, oxygen, and air injector flow areas; (2) combustion efficiency remained essentially constant as the exhaust port area was increased by a factor of 3.4; (3) the mean total temperature determined from integrating the exit radial gas property profiles was within plus or minus 5 percent of the theoretical bulk total temperature; (4) the measured exit total temperature profile had a local peak temperature more than 30 percent greater than the theoretical bulk total temperature; and (5) measured heat transfer to the burner liner was 75 percent of that predicted by theory based on a flat radial temperature profile.
Download or read book Survey of Hydrogen Combustion Properties written by Isadore L. Drell and published by . This book was released on 1957 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt: This literature survey digest of hydrogen-air combustion fundamentals presents data on flame temperature, burning velocity, quenching distance, flammability limits, ignition energy, flame stability, detonation, spontaneous ignition, and explosion limits. The data are assessed, recommended values are given, and relations among various combustion properties are discussed. New material presented includes: theoretical treatment of variation in spontaneous ignition lag with temperature, pressure, and composition, based on reaction kinetics of hydrogen-air composition range for 0.01 to 100 atmospheres and initial temperatures of 0 degrees to 1400 degrees k.
Download or read book An Analytical Study of the Hydrogen air Reaction Mechanism with Application to Scramjet Combustion written by Casimir J. Jachimowski and published by . This book was released on 1988 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Exploratory Investigation of Performance of Experimental Fuel rich Hydrogen Combustion System written by Arthur L. Smith and published by . This book was released on 1958 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Emissions of oxides of nitrogen from an experimental premixed hydrogen burner written by David Nöel Anderson and published by . This book was released on 1976 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Analytical Study of the Hydrogen Air Reaction Mechanism with Application to Scramjet Combustion written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-08-10 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: A chemical kinetic mechanism for the combustion of hydrogen has been assembled and optimized by comparing the observed behavior as determined in shock tube and flame studies with that predicted by the mechanism. The reactions contained in the mechanism reflect the current state of knowledge of the chemistry of the hydrogen/air system, and the assigned rate coefficients are consistent with accepted values. It was determined that the mechanism is capable of satisfactorily reproducing the experimental results for a range of conditions relevant to scramjet combustion. Calculations made with the reaction mechanism for representative scramjet combustor conditions at Mach 8, 16, and 25 showed that chemical kinetic effects can be important and that combustor models which use nonequilibrium chemistry should be used in preference to models that assume equilibrium chemistry. For the conditions examined the results also showed the importance of including the HO2 chemistry in the mechanism. For Mach numbers less than 16, the studies suggest that an ignition source will most likely be required to overcome slow ignition chemistry. At Mach 25, the initial temperature and pressure was high enough that ignition was rapid and the presence of an ignition source did not significantly affect reaction rates. Jachimowski, Casimir J. Langley Research Center NASA-TP-2791, L-16372, NAS 1.60:2791 RTOP 505-62-31-01...
Download or read book Conversion of Gas Turbine Combustors to Operate with a Hydrogen Air Mixture written by Francisco Br√≥jo and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this work, an overview of the use of hydrogen in aviation, the modifications needed to adapt an existent gas turbine to use hydrogen, and a CFD simulation of an existent gas turbine burning hydrogen are performed. The CFD simulation was done in a CFM56-3 combustor burning hydrogen and Jet A. It was intended to evaluate the viability of conversion of existent gas turbines to hydrogen, in a combustion point of view, by analyzing the emissions while burning it through ICAO,Äôs LTO cycle. The pollutant emissions (only NOx, since hydrogen combustion produce only water vapor and NOx) were evaluated through a detailed mechanism and the Ansys Fluent NOx model to get a better agreement with the ICAO,Äôs values. For this assessment, several sensibility studies were made for hydrogen burn, for example, the analysis of the air flow with/without swirl in the primary zone and different inlet temperature and pressure for fuel. In the end, it was concluded that theoretically the CFM56-3 combustor can be converted to operate with hydrogen fuel with minor changes (related to injection system). The quantity of NOx produced for each power setting when burning hydrogen is expected to be almost twice the values for Jet A.
Download or read book Numerical Simulation of Scramjet Combustion in a Shock Tunnel written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Three-dimensional computational simulations of reactive flowfields within a hydrogen-fueled scramjet-like geometry experimentally tested in a free piston shock tunnel are presented. The experimental configuration (Odam and Paull, AIAA Paper 2003-5244) involves injection of hydrogen fuel into the scramjet inlet, followed by mixing, shock-induced ignition, and combustion. The predictions for both fuel-off and fuel-on conditions were observed to be sensitive to the choice of the wall temperature boundary conditions. The best comparison with experimental data were achieved through the implementation of an approach that involves a simplified conjugate heat transfer model that couples the heat conduction through the wall with the heat conduction of the fluid within the boundary layer. This approach is able to predict thermal loads on the walls of the scramjet model due to shock wave interactions and due to heat release. As such, it is able to more accurately represent the physical temperature response of the engine model. Also shown to produce very good agreement with the statistically-steady experimental data was the isothermal ghost-cell boundary condition, which is based on a simplification of the time-dependent conjugate heat transfer boundary condition. This simplified boundary condition assumes a linear temperature distribution within the wall based on the effective depth that an applied heat load would penetrate, thus, it also allows the actual wall temperature to vary in response to the applied heat load. Results for fuel-off simulations showed that the solution generated by a steady-state simulation implementing the isothermal ghost-cell wall boundary condition was very comparable with the statistically-steady solution obtained from a fully transient simulation with coupled heat conduction within the walls. When integrated in a fully time-accurate manner, the fuel-on simulations showed a striking sensitivity to the modeled rate of air ingestion into the engine. F.
Download or read book Effect of Burner Design Variables on Performance of 16 inch diameter Ram jet Combustor Using Gaseous hydrogen Fuel written by H. George Krull and published by . This book was released on 1957 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Theoretical Combustion Performance of Ramjet Fuels Hydrogen written by Waldo T. Renich and published by . This book was released on 1956 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: The report is the first of a series prepared as a compilation of available data on theoretical combustion performance of various fuels. The performance parameters to be given primary consideration are flame temperature and air specific impulse; others, including fuel specific impulse, mole change and expansion ratio are also included.
Download or read book Hydrogen Program Combustion Research written by and published by . This book was released on 1995 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: We have significantly increased our computational modeling capability by the addition of a vertical valve model in KIVA-3, code used internationally for engine design. In this report the implementation and application of the valve model is described. The model is shown to reproduce the experimentally verified intake flow problem examined by Hessel. Furthermore, the sensitivity and performance of the model is examined for the geometry and conditions of the hydrogen-fueled Onan engine in development at Sandia National Laboratory. Overall the valve model is shown to have comparable accuracy as the general flow simulation capability in KIVA-3, which has been well validated by past comparisons to experiments. In the exploratory simulations of the Onan engine, the standard use of the single kinetic reaction for hydrogen oxidation was found to be inadequate for modeling the hydrogen combustion because of its inability to describe both the observed laminar flame speed and the absence of autoignition in the Onan engine. We propose a temporary solution that inhibits the autoignition without sacrificing the ability to model spark ignition. In the absence of experimental data on the Onan engine, a computational investigation was undertaken to evaluate the importance of modeling the intake flow on the combustion and NO(subscript x) emissions. A simulation that began with the compression of a quiescent hydrogen-air mixture was compared to a simulation of the full induction process with resolved opening and closing of the intake valve. Although minor differences were observed in the cylinder-averaged pressure, temperature, bulk-flow kinetic energy and turbulent kinetic energy, large differences where observed in the hydrogen combustion rate and NO(subscript x) emissions. The flow state at combustion is highly heterogeneous and sensitive to the details of the bulk and turbulent flow and that an accurate simulation of the Onan engine must include the modeling of the air-fuel induction.
Download or read book Catalyzed Hydrogen air Combustion in the Supersonic Combustion Ramjet Engine written by Mace Leon Golden and published by . This book was released on 1992 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Characteristics of Hydrogen Combustion in a Direct Injected Constant Volume Combustion Chamber Using Rainbow Schlieren Deflectometry written by Tanisha Latrina Booker and published by . This book was released on 2011 with total page 229 pages. Available in PDF, EPUB and Kindle. Book excerpt: The nation's need for alternative fuels for Internal Combustion Engines (ICEs) has been a major concern for automotive researchers. The need for a sustainable energy system has lead researchers to consider alternative fuels such as hydrogen and thus, several studies have been conducted on this fuel since the 1930s. In particular, understanding the combustion performance of hydrogen at varying equivalence ratios, ignition timings, and volumetric percentages with other fuels is necessary to optimize engine operations. This study investigates the combustion performance of hydrogen injected into a constant volume combustion chamber (CVCC). The properties studied include flame structure, combustion duration, flame front speed, chamber pressure, and net heat transfer rate. The fuel was injected directly into the chamber containing quiescent air at atmospheric pressure. An ignition system consisting of a coil and a spark plug was used to ignite fuel/air mixtures. This study implemented an optical technique, Rainbow Schlieren Deflectometry, to visualize fuel jet penetration, turbulent fuel-air mixing, flame structure, and flame propagation. Schlieren images were analyzed by a cross-correlation technique to compute flame front speed. A dynamic pressure sensor was used to acquire instantaneous chamber pressures which were used to estimate transient chamber net heat transfer rates. First, experiments were conducted by varying the fuel supply pressure to the chamber and the overall equivalence ratio. An investigation of the fuel jet penetration showed that it takes the fuel jet 2.25 ms to reach the igniter. This result was helpful in establishing ignition times for later experiments. Results showed that fuel supply pressure does not affect fuel jet penetration. The fuel jet, however, creates turbulence in the chamber that affects combustion processes. The equivalence ratios tested were [phi] = 1.0, 0.804, and 0.318. Results showed that equivalence ratio has a significant impact on flame front speed which decreased as the equivalence ratio decreased. Next, experiments were conducted to study the effects of ignition time on combustion processes. A programmable logic controller was added to the experimental setup to control ignition time and aid in sequencing events. The ignition times tested were t = 3, 5, and 10 ms in the early ignition group, t = 20, 30, and 40 ms in the mid-ignition group, and t = 60, 80, 240, and 540 ms in the late ignition group, where t = 0 refers to the start of fuel injection. Ignition time affects the flame structure and flame propagation. Results showed that at ignition times prior to the close of the fuel injector, the initial flame front speed is high because of fuel-jet generated turbulence. After the fuel injector closes, increasing the ignition time increases the combustion duration because of dissipating fuel-jet generated turbulence. Ignition time also has significant effects on chamber pressure variations and net heat transfer rates. Next, the effect of ignition time for varying equivalence ratios was studied. Experiments were conducted at three equivalence ratios, [phi] = 0.6, 0.8, and 1.0 and four ignition times, t = 3 ms, 10 ms, tend, and tend + 50 ms. An ultra-high speed camera was incorporated into the experimental setup to acquire schlieren images at a frame rate of 50,000 Hz and exposure time of 19.8μs. Results show that equivalence ratio has minor effects on chamber pressure variations and net heat transfer rate at early ignition times and on flame structure and flame propagation at any ignition times. Ignition time has a significant effect on all combustion processes. Finally, experiments were conducted to determine the effect of hydrogen percentages by volume on methane combustion at varying ignition times. A second high pressure injector was incorporated into the experimental setup to inject the methane into the combustion chamber. Experiments were conducted at the following methane/hydrogen percentages: 23% CH4 - 77% H2, 33% CH4 - 67% H2, 43% CH4 - 57% H2, 53% CH4 - 47% H2, and 63% CH4 - 37% H2. The two ignition times were t = tend and t = tend + 50 ms. Results show that combustion duration decreases as hydrogen percentage increases for identical ignition times, and as ignition time decreases at identical hydrogen percentages. Flame front speed increases as hydrogen percentage increases. Peak chamber pressure and peak net heat transfer rate decreases for the late ignition time at fixed hydrogen percentages.
Download or read book NASA Technical Note written by and published by . This book was released on 1977 with total page 938 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Parallel Modeling of Three Dimensional Scramjet Combustor and Comparisons with Experiment s Results written by and published by . This book was released on 2002 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this paper a parallel simulation of an experimental dual-mode scramjet combustor configuration is presented. Turbulence is modeled with the kappa-epsilon two-equation turbulence model and a 7-species 8-equation kinetics model is used to model hydrogen/air combustion. The conservation from of the Navier-Stokes equations with finite-rate chemistry reactions is solved using a diagonal implicit finite-volume method. Using about 3,12O,000 grid points the three-dimension flow-fields with equivalence ratio phi=0.0 and 0.35 have been respectively simulated on the parallel computer system obtaining more detailed flow properties than the experiment's results. Wall pressure comparisons between CFD and experiment show fair agreement. For phi=0.35 the fuel-penetrating height of the seven injectors are different because of the effects of the boundary layer and the shock wave in the combustor. According to numerical results, if adjusting the locations of the injectors the combustion efficiency could be improved.
Download or read book NASA Technical Paper written by and published by . This book was released on 1988 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 702 pages. Available in PDF, EPUB and Kindle. Book excerpt:
