Particulate multi-phase flowfield with chemical reaction for a 2D advanced solid rocket motor (AS... more Particulate multi-phase flowfield with chemical reaction for a 2D advanced solid rocket motor (ASRM) is analyzed using the finite difference Navier-Stokes (FDNS) code. The flowfield in the aft dome cavity of the ASRM is examined and its significant impact on the motor operation and performance is demonstrated. Chemical reaction analysis is performed for H2O, O2, H2, O, H, OH, CO, CO2, Cl, Cl2, HCl, and N2. The turbulent dispersion effect is calculated with the Monte Carlo method. Result show that a recirculation zone exists at the entry of the aft-dome cavity. The particle impingement could cause the erosion and damage nozzle wall. Accumulating in the impingement area the particles change the wall shape and affect the motor performance.
Using a pulsed CO2 laser test-bed the properties of a laser lightcraft are investigated with resp... more Using a pulsed CO2 laser test-bed the properties of a laser lightcraft are investigated with respect to the thrust generating mechanisms. New optical diagnostics allow to measure the mechanical impulse imparted to the lightcraft by the laser pulse with high accuracy. Density variations are measured with a HeNe probe laser and identified as shock waves originating from the laser-induced air breakdown. Wire guided indoor vertical flights are demonstrated with accelerations of about 1 g. Satisfactory agreement between theory and experiment in the time-space domain is found using a strong explosion model. Prediction of mission requirements suggests that lightcrafts of 1 - 10 kg can be placed into orbit with current technology.
The component part is provided here to allow users access to individually authored sections f pro... more The component part is provided here to allow users access to individually authored sections f proceedings, annals, symposia, etc. However, the component should be considered within [he context of the overall compilation report and not as a stand-alone technical report. The following component part numbers comprise the compilation report: ADP012355 thru ADP012373
The objective of this effort is to develop an efficient and accurate thermo-fluid computational m... more The objective of this effort is to develop an efficient and accurate thermo-fluid computational methodology to predict environments for a solid-core, nuclear thermal engine thrust chamber. The computational methodology is based on an unstructured-grid, pressure-based computational fluid dynamics formulation. A two-pronged approach is employed in this effort: A detailed thermo-fluid analysis on a multi-channel flow element for mid-section corrosion investigation; and a global modeling of the thrust chamber to understand the effect of heat transfer on thrust performance. Preliminary results on both aspects are presented.
Lateral nozzle forces are known to cause severe structural damage to any new rocket engine in dev... more Lateral nozzle forces are known to cause severe structural damage to any new rocket engine in development during test. While three-dimensional, transient, turbulent, chemically reacting computational fluid dynamics methodology has been demonstrated to capture major side load physics with rigid nozzles, hot-fire tests often show nozzle structure deformation during major side load events, leading to structural damages if structural strengthening measures were not taken. The modeling picture is incomplete without the capability to address the two-way responses between the structure and fluid. The objective of this study is to develop a tightly coupled aeroelastic modeling algorithm by implementing the necessary structural dynamics component into an anchored computational fluid dynamics methodology. The computational fluid dynamics component is based on an unstructured-grid, pressure-based computational fluid dynamics formulation, while the computational structural dynamics component is...
INTRODUCTIONCurrently, NASA's aim of operating low cost launch and space vehiclesrequires the... more INTRODUCTIONCurrently, NASA's aim of operating low cost launch and space vehiclesrequires the research and development of advanced propulsion technologies andconcepts. One plausible advanced concept is the utilization of off-board pulsedlaser power source to propel small payload (e.g. 100kg) into earth orbit. Themerit of the laser-propelled vehicles is in its high efficiency (do not need to carryfuel) and high specific impulse. Previous SDIO research led to the invention ofthe one of the laser powered launch vehicle concept - the Laser Lightcraftconcept, currently being tested at the High Energy Laser Test System Facility,White Sands Missile Range, New Mexico. Although the spin-stabilized smallscale Lightcraft model (invented by Myrabo) has been flown successfully up to analtitude of 30 meters using a 10 kW pulsed-laser at 10 Hz, many technical issuesneed to be addressed before an optimized design of the vehicle and its operationcan be achieved.The purpose of this study is to establish the technical ground for modelingthe physics of laser powered pulse detonation phenomenon. The principle of thelaser power propulsion is that when high-powered laser is focused at a smallarea near the surface of a thruster, the intense energy causes the electricalbreakdown of the working fluid (e.g. air) and forming high speed plasma (knownas the inverse Bremsstrahlung, IB, effect). The intense heat and high pressurecreated in the plasma consequently causes the surrounding to heat up andexpand until the thrust producing shock waves are formed. This complexprocess of gas ionization, increase in radiation absorption and the forming ofplasma and shock waves will be investigated in the development of the presentnumerical model. In the first phase of this study, laser light focusing, radiativeabsorption and shock wave propagation over the entire pulsed cycle aremodeled. The model geometry and test conditions of known benchmarkexperiments such as those in Myrabo's experiment will be employed in thenumerical model validation simulations. The calculated performance data (e.g.coupling coefficients) will be compared to the test data. Plans for the numerical
Stage separation process is an important phenomenon in multi-stage launch vehicle operation. The ... more Stage separation process is an important phenomenon in multi-stage launch vehicle operation. The transient flowfield coupled with the multi-body systems is a challenging problem in design analysis. The thermodynamics environment with burning propellants during the upper-stage engine start in the separation processes adds to the complexity of the-entire system. Understanding the underlying flow physics and vehicle dynamics during stage separation is required in designing a multi-stage launch vehicle with good flight performance. A computational fluid dynamics model with the capability to coupling transient multi-body dynamics systems will be a useful tool for simulating the effects of transient flowfield, plume/jet heating and vehicle dynamics. A computational model using generalize mesh system will be used as the basis of this development. The multi-body dynamics system will be solved, by integrating a system of six-degree-of-freedom equations of motion with high accuracy. Multi-body mesh system and their interactions will be modeled using parallel computing algorithms. Adaptive mesh refinement method will also be employed to enhance solution accuracy in the transient process.
Computational Transport Phenomena Overview Transport Phenomena Analyzing Transport Phenomena A Co... more Computational Transport Phenomena Overview Transport Phenomena Analyzing Transport Phenomena A Computational Tool: The CTP Code Verification, Validation, and Generalization Summary Nomenclature References The Equations of Change Introduction Derivation of The Continuity Equation Derivation of The Species Continuity Equation Derivation of The Equation Of Motion Derivation of The General Energy Equation Non-Newtonian Fluids General Property Balance Analytical and Approximate Solutions for the Equations of Change Summary Nomenclature References Physical Properties Overview Real-Fluid Thermodynamics Chemical Equilibrium and Reaction Kinetics Molecular Transport Properties Thermal Radiation Properties Nomenclature References Turbulence Modeling Concepts Reynolds Averaging and Eddy Viscosity Models Turbulence Characteristics Reynolds and Favre Averaging Eddy Viscosity Models Nomenclature Appendix 4.A: Basic Probability Parameters References Other Turbulence Models More Comprehensive Turbulence Models Differential Second-Moment Closure Methods Probability Density Function Models Direct Numerical Simulation Large Eddy Simulation Laminar-To-Turbulent Transition Models Nomenclature References Computational Coordinates and Conservation Laws Overview Coordinates Conservation Laws in Computational Coordinates Transformed CTP Equations Nomenclature Appendix 6.A Transformed Terms Which Complete the System of Conservation Laws References Numerical Methods for Solving Governing Equations Overview Density-Based and Pressure-Based Methods Numerical Methods Grid Topologies Space-Time Conservation-Element/Solution-Element Methods Nomenclature References The CTP Code Grids Discretized Conservation Equations Upwind and Dissipation Schemes Solution Strategy Time-Marching Scheme Boundary Conditions Initial Conditions CTP Code Features User's Guide Nomenclature Multiphase Phenomena Scope Dilute Suspensions Interphase Mass Transfer Multiphase Effects Included in the CTP Code Population Balance Models Dense Particulate Flows Nomenclature References Closure References APPENDIX A: Grid Stencils and Example Problems APPENDIX B: Rudiments of Vector and Tensor Analysis APPENDIX C: Fortran Primer Index
23rd Fluid Dynamics, Plasmadynamics, and Lasers Conference, 1993
A third-order Total Variation Diminishing (TVD) scheme has been implemented in a pressure-based N... more A third-order Total Variation Diminishing (TVD) scheme has been implemented in a pressure-based Navier-Stokes solver for the analysis of complex viscous flow problems. The Chakravarthy-Osher third-order TVD flux limiter was employed and reformulated for the convection terms of the governing equations. Together with the capabilities of time accuracy for all-speed range, general and robust turbulence models (i.e. two-equation turbulence model with compressibility corrections), efficient finite-rate chemistry solution methods, multiple-zone general coordinates mesh system, and realistic two-phase flow models for spray combustion, embedded in the computational fluid dynamics (CFD) code, many complex flow problems can be analyzed. Results of this study show that with the third-order TVD scheme provides better resolutions for flow variables with spatial discontinuities.
This paper presents parallelized, solution adaptive, multi-grid hybrid unstructured methods to th... more This paper presents parallelized, solution adaptive, multi-grid hybrid unstructured methods to the turbulent flows past complex configurations. The numerical techniques are accomplished by parallel computing algorithm with multi options of serial, PVM or MPI to accommodate any type of machines, hanging node solution adaptation, algebraic multi-grid speeding-up convergence method. With the enhancement of higher order scheme data reconstruction, higher order upwind-biased differencing, multi-pressure-correction, and Bi-CGSTAB and GMRES matrix solvers, the proposed methods can efficiently and accurately handle flow problems in several cases including benchmark and practical. Very good convergence and accurate solutions have been demonstrated even for complex 3D configurations under high Reynolds number turbulent flow conditions.
Hybrid rocket propulsion is deemed to be advantageous to its solid and liquid counterparts for th... more Hybrid rocket propulsion is deemed to be advantageous to its solid and liquid counterparts for the safety nature of the designs. With the proposed innovation in this research using dual-vortical-flow (DVF) chambers, hybrid rocket engines can also deliver thrust performance close to that of kerosene liquid engines but with much reduced production cost. Based on this new approach and cost saving strategy, a multifunction sounding rocket system is designed with the features of high performance hybrid combustion, trajectory following flight controls, enhanced science experiments, and an advanced payload recovery method. High fidelity numerical modeling design approach and hot-fire experiments are employed to assess the overall performance of the DVF hybrid rocket engines that has roll control capability embedded in the design. Three basic flight trajectory designs are proposed in this study, namely the traditional standard parabolic trajectory, a TASE (Trajectory Augmented Science Experiments) maneuver and a HOOK (Homing Oriented Operation Kernel) maneuver. The TASE maneuver is designed for maximizing the measurement capabilities of the instruments for atmospheric and ionosphere data profiles. The HOOK maneuver is aiming at improving the success in science payload recovery and in reducing the search and recovery efforts. To achieve these goals, a high performance and reliable flight control system is critical, that incorporates the throttling capability of the DVF hybrid rocket engine, which is one of the key development aspects of this study.
Particulate multi-phase flowfield with chemical reaction for a 2D advanced solid rocket motor (AS... more Particulate multi-phase flowfield with chemical reaction for a 2D advanced solid rocket motor (ASRM) is analyzed using the finite difference Navier-Stokes (FDNS) code. The flowfield in the aft dome cavity of the ASRM is examined and its significant impact on the motor operation and performance is demonstrated. Chemical reaction analysis is performed for H2O, O2, H2, O, H, OH, CO, CO2, Cl, Cl2, HCl, and N2. The turbulent dispersion effect is calculated with the Monte Carlo method. Result show that a recirculation zone exists at the entry of the aft-dome cavity. The particle impingement could cause the erosion and damage nozzle wall. Accumulating in the impingement area the particles change the wall shape and affect the motor performance.
Using a pulsed CO2 laser test-bed the properties of a laser lightcraft are investigated with resp... more Using a pulsed CO2 laser test-bed the properties of a laser lightcraft are investigated with respect to the thrust generating mechanisms. New optical diagnostics allow to measure the mechanical impulse imparted to the lightcraft by the laser pulse with high accuracy. Density variations are measured with a HeNe probe laser and identified as shock waves originating from the laser-induced air breakdown. Wire guided indoor vertical flights are demonstrated with accelerations of about 1 g. Satisfactory agreement between theory and experiment in the time-space domain is found using a strong explosion model. Prediction of mission requirements suggests that lightcrafts of 1 - 10 kg can be placed into orbit with current technology.
The component part is provided here to allow users access to individually authored sections f pro... more The component part is provided here to allow users access to individually authored sections f proceedings, annals, symposia, etc. However, the component should be considered within [he context of the overall compilation report and not as a stand-alone technical report. The following component part numbers comprise the compilation report: ADP012355 thru ADP012373
The objective of this effort is to develop an efficient and accurate thermo-fluid computational m... more The objective of this effort is to develop an efficient and accurate thermo-fluid computational methodology to predict environments for a solid-core, nuclear thermal engine thrust chamber. The computational methodology is based on an unstructured-grid, pressure-based computational fluid dynamics formulation. A two-pronged approach is employed in this effort: A detailed thermo-fluid analysis on a multi-channel flow element for mid-section corrosion investigation; and a global modeling of the thrust chamber to understand the effect of heat transfer on thrust performance. Preliminary results on both aspects are presented.
Lateral nozzle forces are known to cause severe structural damage to any new rocket engine in dev... more Lateral nozzle forces are known to cause severe structural damage to any new rocket engine in development during test. While three-dimensional, transient, turbulent, chemically reacting computational fluid dynamics methodology has been demonstrated to capture major side load physics with rigid nozzles, hot-fire tests often show nozzle structure deformation during major side load events, leading to structural damages if structural strengthening measures were not taken. The modeling picture is incomplete without the capability to address the two-way responses between the structure and fluid. The objective of this study is to develop a tightly coupled aeroelastic modeling algorithm by implementing the necessary structural dynamics component into an anchored computational fluid dynamics methodology. The computational fluid dynamics component is based on an unstructured-grid, pressure-based computational fluid dynamics formulation, while the computational structural dynamics component is...
INTRODUCTIONCurrently, NASA's aim of operating low cost launch and space vehiclesrequires the... more INTRODUCTIONCurrently, NASA's aim of operating low cost launch and space vehiclesrequires the research and development of advanced propulsion technologies andconcepts. One plausible advanced concept is the utilization of off-board pulsedlaser power source to propel small payload (e.g. 100kg) into earth orbit. Themerit of the laser-propelled vehicles is in its high efficiency (do not need to carryfuel) and high specific impulse. Previous SDIO research led to the invention ofthe one of the laser powered launch vehicle concept - the Laser Lightcraftconcept, currently being tested at the High Energy Laser Test System Facility,White Sands Missile Range, New Mexico. Although the spin-stabilized smallscale Lightcraft model (invented by Myrabo) has been flown successfully up to analtitude of 30 meters using a 10 kW pulsed-laser at 10 Hz, many technical issuesneed to be addressed before an optimized design of the vehicle and its operationcan be achieved.The purpose of this study is to establish the technical ground for modelingthe physics of laser powered pulse detonation phenomenon. The principle of thelaser power propulsion is that when high-powered laser is focused at a smallarea near the surface of a thruster, the intense energy causes the electricalbreakdown of the working fluid (e.g. air) and forming high speed plasma (knownas the inverse Bremsstrahlung, IB, effect). The intense heat and high pressurecreated in the plasma consequently causes the surrounding to heat up andexpand until the thrust producing shock waves are formed. This complexprocess of gas ionization, increase in radiation absorption and the forming ofplasma and shock waves will be investigated in the development of the presentnumerical model. In the first phase of this study, laser light focusing, radiativeabsorption and shock wave propagation over the entire pulsed cycle aremodeled. The model geometry and test conditions of known benchmarkexperiments such as those in Myrabo's experiment will be employed in thenumerical model validation simulations. The calculated performance data (e.g.coupling coefficients) will be compared to the test data. Plans for the numerical
Stage separation process is an important phenomenon in multi-stage launch vehicle operation. The ... more Stage separation process is an important phenomenon in multi-stage launch vehicle operation. The transient flowfield coupled with the multi-body systems is a challenging problem in design analysis. The thermodynamics environment with burning propellants during the upper-stage engine start in the separation processes adds to the complexity of the-entire system. Understanding the underlying flow physics and vehicle dynamics during stage separation is required in designing a multi-stage launch vehicle with good flight performance. A computational fluid dynamics model with the capability to coupling transient multi-body dynamics systems will be a useful tool for simulating the effects of transient flowfield, plume/jet heating and vehicle dynamics. A computational model using generalize mesh system will be used as the basis of this development. The multi-body dynamics system will be solved, by integrating a system of six-degree-of-freedom equations of motion with high accuracy. Multi-body mesh system and their interactions will be modeled using parallel computing algorithms. Adaptive mesh refinement method will also be employed to enhance solution accuracy in the transient process.
Computational Transport Phenomena Overview Transport Phenomena Analyzing Transport Phenomena A Co... more Computational Transport Phenomena Overview Transport Phenomena Analyzing Transport Phenomena A Computational Tool: The CTP Code Verification, Validation, and Generalization Summary Nomenclature References The Equations of Change Introduction Derivation of The Continuity Equation Derivation of The Species Continuity Equation Derivation of The Equation Of Motion Derivation of The General Energy Equation Non-Newtonian Fluids General Property Balance Analytical and Approximate Solutions for the Equations of Change Summary Nomenclature References Physical Properties Overview Real-Fluid Thermodynamics Chemical Equilibrium and Reaction Kinetics Molecular Transport Properties Thermal Radiation Properties Nomenclature References Turbulence Modeling Concepts Reynolds Averaging and Eddy Viscosity Models Turbulence Characteristics Reynolds and Favre Averaging Eddy Viscosity Models Nomenclature Appendix 4.A: Basic Probability Parameters References Other Turbulence Models More Comprehensive Turbulence Models Differential Second-Moment Closure Methods Probability Density Function Models Direct Numerical Simulation Large Eddy Simulation Laminar-To-Turbulent Transition Models Nomenclature References Computational Coordinates and Conservation Laws Overview Coordinates Conservation Laws in Computational Coordinates Transformed CTP Equations Nomenclature Appendix 6.A Transformed Terms Which Complete the System of Conservation Laws References Numerical Methods for Solving Governing Equations Overview Density-Based and Pressure-Based Methods Numerical Methods Grid Topologies Space-Time Conservation-Element/Solution-Element Methods Nomenclature References The CTP Code Grids Discretized Conservation Equations Upwind and Dissipation Schemes Solution Strategy Time-Marching Scheme Boundary Conditions Initial Conditions CTP Code Features User's Guide Nomenclature Multiphase Phenomena Scope Dilute Suspensions Interphase Mass Transfer Multiphase Effects Included in the CTP Code Population Balance Models Dense Particulate Flows Nomenclature References Closure References APPENDIX A: Grid Stencils and Example Problems APPENDIX B: Rudiments of Vector and Tensor Analysis APPENDIX C: Fortran Primer Index
23rd Fluid Dynamics, Plasmadynamics, and Lasers Conference, 1993
A third-order Total Variation Diminishing (TVD) scheme has been implemented in a pressure-based N... more A third-order Total Variation Diminishing (TVD) scheme has been implemented in a pressure-based Navier-Stokes solver for the analysis of complex viscous flow problems. The Chakravarthy-Osher third-order TVD flux limiter was employed and reformulated for the convection terms of the governing equations. Together with the capabilities of time accuracy for all-speed range, general and robust turbulence models (i.e. two-equation turbulence model with compressibility corrections), efficient finite-rate chemistry solution methods, multiple-zone general coordinates mesh system, and realistic two-phase flow models for spray combustion, embedded in the computational fluid dynamics (CFD) code, many complex flow problems can be analyzed. Results of this study show that with the third-order TVD scheme provides better resolutions for flow variables with spatial discontinuities.
This paper presents parallelized, solution adaptive, multi-grid hybrid unstructured methods to th... more This paper presents parallelized, solution adaptive, multi-grid hybrid unstructured methods to the turbulent flows past complex configurations. The numerical techniques are accomplished by parallel computing algorithm with multi options of serial, PVM or MPI to accommodate any type of machines, hanging node solution adaptation, algebraic multi-grid speeding-up convergence method. With the enhancement of higher order scheme data reconstruction, higher order upwind-biased differencing, multi-pressure-correction, and Bi-CGSTAB and GMRES matrix solvers, the proposed methods can efficiently and accurately handle flow problems in several cases including benchmark and practical. Very good convergence and accurate solutions have been demonstrated even for complex 3D configurations under high Reynolds number turbulent flow conditions.
Hybrid rocket propulsion is deemed to be advantageous to its solid and liquid counterparts for th... more Hybrid rocket propulsion is deemed to be advantageous to its solid and liquid counterparts for the safety nature of the designs. With the proposed innovation in this research using dual-vortical-flow (DVF) chambers, hybrid rocket engines can also deliver thrust performance close to that of kerosene liquid engines but with much reduced production cost. Based on this new approach and cost saving strategy, a multifunction sounding rocket system is designed with the features of high performance hybrid combustion, trajectory following flight controls, enhanced science experiments, and an advanced payload recovery method. High fidelity numerical modeling design approach and hot-fire experiments are employed to assess the overall performance of the DVF hybrid rocket engines that has roll control capability embedded in the design. Three basic flight trajectory designs are proposed in this study, namely the traditional standard parabolic trajectory, a TASE (Trajectory Augmented Science Experiments) maneuver and a HOOK (Homing Oriented Operation Kernel) maneuver. The TASE maneuver is designed for maximizing the measurement capabilities of the instruments for atmospheric and ionosphere data profiles. The HOOK maneuver is aiming at improving the success in science payload recovery and in reducing the search and recovery efforts. To achieve these goals, a high performance and reliable flight control system is critical, that incorporates the throttling capability of the DVF hybrid rocket engine, which is one of the key development aspects of this study.
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