X summary of the injector design specifications are provided in table 1. Pdf impinging fuel injector atomization and combustion. In some injector design applications, such as a zoned combustor. The injector face has 1428 oxidizer orifices and 1404 fuel orifices for a total of 2832 total orifices. Breakup characteristics of powerlaw liquid sheets formed.
A good agreement between the theory and the experiment was seen for both the critical wave lengths and the breakup lengths in the case of a high viscous. Rheological characterization and surface tension measurements of gel fuel mixtures were obtained to demonstrate their nonnewtonian. The orifices are arranged in pairs such that the propellant being expelled through the holes intersect or impinge in a doublet, likeonlike. Individual injector test is usually taken under atmosphere conditions to get the mass flux distribution of the injector, which is then used to design the injector distribution patterns. The resultant momentum after impingement should be purely axial and the angle between the oxidizer and fuel jets is 60 degrees. The most common of these, a doublet type, has two likefluid streams angles together to an impact point, producing a fan shaped spray of droplets similar to that of an unlike doublet. Doublet injectors have been studied parametrically in past work focusing on, for example, orifice length to diameter ratio, impingement angle, and injection velocity. The experiment uses planar laser induced fluorescence technique to investigate the mixing efficiencies of impinging liquid streams. Plain and gelled water were used as working fluids. The characteristics of sprays produced by liquid rocket injectors are important in understanding rocket engine ignition and performance. Comparison of like on like doublet and triplet impinging. The addition of this material, sodium borohydride, renders the reactants hypergolic.
Solved determine the hole sizes and the angle setting. Several aspects of the atomization behavior of various. First, a transient impingement spray during engine startup. Coupled lagrangian impingement spray model for doublet impinging injectors under liquid rocket engine operating conditions. Numerical simulation of the atomization process of a like doublet impinging rocket injector. Spray characterization of likeonlike doublet impinging. Numerical simulation of the atomization process of a like. Fuel and oxidizer feed systems amazon web services. However, studies on breakup characteristics of nonnewtonian liquid sheets are fewer. A comparison of three types of likeonlike impinging jet injectors under ambient conditions is conducted. It is here, in the injector, where the mixing occurs.
Liquid mixing in doublet impinging jet injectors using x. The spray formation of gelled propellant from impinging jet injectors with a helmholtz resonatorlike. Effects of ambient gas pressure on the breakup of sprays. The atomization and mixing of like doublet water impinging jets at different ambient pressures 1. It is concluded that the flames driving unsteady acoustics are those located at the. Goddards first liquidfuel engine used a single impinging injector. Coupled levelsetvolumeoffluid method for simulation of.
The atomization characteristics of skewed likeonlike impinging injectors were studied using water as a simulant. Reliability study on skewness of doublet impinging injectors. A simplified linear model and breakup characteristics of powerlaw sheet formed by a doublet impinging injector hanyu deng, changfei zhuo, and feng feng proceedings of the institution of mechanical engineers, part g. The results of an investigation to characterize sprays generated by likeonlike doublet impinging injectors are described. Design and analysis of fuel injector nozzle for rocket engines. While studies have shown that higher theoretical specific impulse isp values can be obtains with ofo injector systems, lol systems are traditionally more reliable and exhibit greater combustion. By impinging the jet streams of fuel and oxidizer, the spray spreads while the two liquids mix.
The orifice diameter and length of the nozzle used in this work were of 0. To design the injectors, several correlations related to injection conditions have been proposed e. An injection system based on prefixing the mass flow rate of the atomized fluid was designed and built. The two primary injection styles that were considered were unlike triplet impinging jets ofo and like on like doublet impinging jets lol.
Mixing characteristics of nonnewtonian impinging jets at. Impinging fuel injector atomization and combustion. The main type of injectors are shower head type self impinging doublet type cross impinging triplet type centrifugal or swirling type pintle injector type the pintle injector permits good mixture. Experimental comparative study of doublet and triplet. The coaxial and impinging jets injectors are two of the wellestablished designs in. Towards highfidelity multiscale simulation of spray atomization. The pintle injector permits good mixture control of fuel and oxidizer over a wide range of flow rates. Injector driver modules, also known as idms, work with the central computer system and the fuel injection system in a vehicle.
Doublet impinging injectors are frequently used in bipropellant hypergolic liquid rocket engines for rapid atomization and mixing in a short distance. Hoehn and coworkers studied orifice shape alignment and cavitation and their effects on mixing and discovered noncircular orifices may be better for mixing but are more sensitive to alignment 18. Comparison of like on like doublet and triplet impinging jet injectors. The includes, but is not limited to, drop size distribution, spray density, drop velocity, oscillations in the spray, uniformity of mixing between propellants, and the spatial distribution of drops. The effect of chamber pressure on the mixing characteristics of like doublet impinging liquid jets is experimentally and numerically investigated for nongelled and gelled hypergolic propellant simulants. Combustion instability phenomena of importance to liquid. In other words, strouhal number of impinging injectors is smaller than 0. The fourth injector configuration was a likeonlike doublet of. The oxidizer and fuel react as soon as the two jets collide and break up into droplets. The most common of these, a doublet type, has two likefluid streams angles together to an impact point, producing a fan shaped spray of. Hypergolic combustion chamber interfaced with ij apparatus to allow combustion studies at elevated pressures click for details.
The results indicate a tendency of the droplet size to decrease with the mass. Design and analysis of a fuel injector of a liquid rocket. Injector desxgss like doublet subscale ini ector a total of i1 injector configurations were designed. Three types of impinging jet atomizers doublet, triplet, and quadruplet at two impinging angles were utilized. Impinging jet experiments were conducted using doublet, triplet, and quintuplet injector configurations to measure ignition delay of hydrogen peroxide h 2 o 2 with gelled hydrocarbon fuel containing reactive particles. Impinging fuel injector atomization and combustion modeling. The three atomizers are a doublet, a linear triplet and a 3d or circular triplet injector. The injector is located just above the main combustion chamber. The mass distributions of the impinging jets from the cold flow observations are used to arrange the paired orifices of the impinging unit on.
However, they focused on the detailed atomization process of liquid sheets and dealt with monoliquid. The resultant momentum should be axial, and the angle between the oxygen and fuel jets. The observation of the atomization and mixing of doublet. Rahimi and natan 2 used an airblast triplet injector to. Choosing injector type assuming bipropellant lre, major considerations are hypergolic or not must prevent any premixing of propellants historically impingementtype, pintle on lmde. Freesurface flow simulation of unlikedoublet impinging. Periodic atomization characteristics of an impinging jet injector. Determine the hole sizes and angle settings for a fourelement unlike fuel on oxidizer impinging injector two fuel holes and two oxidizer holes. Recent experimental efforts on highpressure supercritical injection.
Like impinging or selfimpinging elements impinge the injected streams directly on other streams of the same propellant. The shadowgraph technique and laser deflection analyzer were used to understand the variances in spray mode, breakup length, and spray angles with the fraction of skewness under different angles of impingement, pressure. However, the amount of experiments using actual liquid propellants such as mmh or nto does not suf. This injector configuration is being considered for use in a liquidliquidgas tripropellant rocket combustor. A liquidpropellant rocket or liquid rocket utilizes a rocket engine that uses liquid propellants. An unlike doublet impinging jet apparatus is used to characterize the ignition and combustion of both neat and gelled hypergols. Schematic of a like doublet impinging jet injector. Hypergolic ignition and the associated ignition delay times. For the present work the impingement angle 2t of 50 deg and 80 deg and a preimpingement length l of 5mm have been chosen. Haynes 230 6 design selection recap huzel, dieter, and david huang. The effect of doublet injector orifice geometry on spray. However, limited studies describe the mixing characteristics of like doublet injectors at elevated ambient pressures for both nongelled and gelled fluid injection. Goddards first liquid fuel engine used a single impinging injector.
Like impinging or self impinging elements impinge the injected streams directly on other streams of the same propellant. Coupled lagrangian impingement spray model for doublet. Angular relation of doublet impingingstream injection pattern. The outermost ring consists of fuel elements pairs of 0.
Influence of the viscosity ratio on drop dynamics and breakup for a drop rising in an immiscible lowviscosity liquid. Like doublet injector the self impinging doublet injector, designed specifically for ablative applications, incorporates 80 elements arranged in a radial pattern of alternating fuel and oxidizer rings fig. Oleg prokopov motion control, algorithms and autonomous. Engines that need high pressure fuel injection rely on injector driver modules to control the fuel injection system. Impinging jet experiments were conducted using doublet, triplet, and quintuplet injector configurations to measure ignition delay of hydrogen peroxide with gel hydrocarbon fuel containing sodium borohydride nabh4 particles. The effect of orifice geometry has been comparatively understudied although it has a significant impact on the impinging jet stream dynamics. Modern engineering for design of liquidpropellant rocket engines. Injectors thrust chambers questions and answers sanfoundry. Only vehicles with fuelinjection systems will use an injector driver module. Spray characteristics of gelled propellants in novel impinging jet. The distance from the exit of the orifice to the impingement point was fixed at 9. Performed 1d flow analysis on like doublet, self impinging injector, then machined it waterflow tested injector with 100 psia upstream tank pressure and imaged atomization. Linux debugging, linux device drivers, linux networking, linux storage, advanced c programming, san storage technologies, scsi internals.
Determine the hole sizes and the angle setting for a multiplehole, doublet impinging stream injector that uses alcohol and liquid oxygen as propellants. The spray characterization is carried out with a malvern spraytech, an instrument based on laser diffraction, for measuring the spray droplets size and with the shadowgraph technique which allows the visualization of the spray shape and patterns. A simplified linear model and breakup characteristics of. The pintle injector was used in the apollo lunar module engines descent propulsion system and the kestrel engine, it is currently used in the merlin engine on. A study on impinging flow characterization of unlike doublet injector for liquid rocket engine korea aerospace conference sep 2002 check the penetration length between oxidant and.
So far, designing the injector of a thruster tends to rely on the designers experiences and numerous experiments conducted in the past. Associate professsor, department of mechanical engineering, college of engineering, trivandrum, kerala, 695016, india abstract impinging jet injectors has often been a preferred configuration in liquid propellant rockets, the most common form of which is the liquidonliquid doublet. The spray formation of gelled propellant from impinging jet injectors with a. The impingingtype injector design of mmhnto liquid.
Rheological characterization and surface tension measurements of gel fuel mixtures were obtained to demonstrate their. The function of the injector is similar to those of a carburetor of an internal combustion engine. Rocket propulsion questions and answers thrust chambers injectors. It could be observed that with increasing jet velocity the breakup behavior of the investigated fluids. However, since a wide range of liquid properties, liquid flow rates, and chamber densities were used in this investigation, the results are not limited to a. The atomization characteristics of various newtonian fluids with a doublet likeonlike impinging jet injector under ambient pressure and temperature conditions and jet velocities up to 80 ms was investigated and compared. Liquid and gelled sprays for mixing hypergolic propellants. This helps to break the flow up into small droplets that burn more easily. An acoustic driver with its highest efficiency in the thousand hertz range was attached. The experimental setup consisted of an acoustic driver and a highpressure. Liquidpropellant rocket injectors types of injectors. The most common of these, a doublet type, has two likefluid streams angles together to an impact point, producing a fan shaped spray of droplets similar to that.
The design of the multipair impinging injector plate is based on the cold flow and hot fire observations of unlike doublet impinging jets of monomethylhydrazinenitrogen tetroxide and their simulants. Therefore, the objective of this study is to quantify mixing between. Impinging jet ignition studies of hydrogen peroxide with. The diameter d j of the two jets is takes the common value of 1mm.