Innovative methods for improving combustion properties of solid propellants for hybrid rocket propulsion. Aerospace 2019, 6, 47. Modeling the regression rate of high density polyethylene in the simulation of hybrid rocket flow fields. Aerospace 2019, 6, 88.
Postscript for Special Issue “Advances in Hybrid Rocket Technology and Related
Analysis Methodologies”
Hybrid Rocket Underwater Propulsion: A Preliminary Assessment
- Introduction
- Underwater Setup
- Results and Discussion
- Conclusions
Figure 2 shows the schematic of the experimental setup for the laboratory-scale 500 N class hybrid rocket engine used for the static tests. On the contrary, the chamber pressure can interact with the gas bag (filled with hot gas) downstream of the nozzle in case of.
Viability of an Electrically Driven Pump-Fed Hybrid Rocket for Small Launcher Upper Stages
Numerical Models
- GPFS
- EPFS
A unit variable is associated with each equation; optimal control theory provides the Euler-Lagrange equations, algebraic equations that define the control variables (i.e., the direction of thrust) and the boundary conditions for optimality (which also implicitly define the motor shift timing). The solutions, here called particles, fly through the problem space following the optimal particle (i.e., the alpha member of the swarm or school).
Numerical Results
In Proceedings of the 51st AIAA/SAE/ASEE Joint Propulsion Conference, AIAA Propulsion and Energy Forum, Orlando, FL, VS, 27–29 juli 2015. In Proceedings of the 53rd AIAA/SAE/ASEE Joint Propulsion Conference, AIAA Propulsion and Energy Forum, Atlanta, GA, VS, 10–12 juli 2017.
Comprehensive Data Reduction for N 2 O/HDPE Hybrid Rocket Motor Performance Evaluation
Materials and Methods
The operational flow of the comprehensive data reduction procedure used in this research is shown in Figure 3. Here, Tn1 is the temperature at the position of the thermocouple located closest to the nozzle orifice in K.
Results
The main discrepancy is the large difference in the solution of the fuel regression rate exponent, n. The results of the TTRT for time-averaged values of the nozzle throat wall temperature are listed in Table 2asTwin K.
Innovative Methods to Enhance the Combustion
Properties of Solid Fuels for Hybrid Rocket Propulsion
Literature Survey and Objective
Methods to increase the fuel regression rate mainly consist of improving the heat feedback (nanometallized fuels), promoting condensed phase reactions (using high energy binder such as Guanidinium Azo-Tetrazolate (GAT) [8] and Glycidyl Azide Polymer (GAP) to decrease the decomposition heat or adding (AP) [9] low ammonium perchloroporate to fuel. ization fuels such as paraffin liquid fuels [10–14] to promote a mass transfer mechanism , increasing oxidation turbulence (swirling injector [9,15,16] or helical spikes port injector [17]), designing multi-port grains (star and cartwheel type to increase the hybrid 2 oxidizing area or porous] hybrid 2) [19] and LO2-N2O [20,21]). Carmicino and Russo-Sorge [25] tested a laboratory-scale hybrid rocket burning gaseous oxygen in a center-perforated cylindrical solid grain and, with respect to pure HTPB, verified for several high-energy fuel additives limited effects in terms of increase in regression rate (e.g. characteristic oxygen rate based on 20%-15) and impulse efficiency (around 95% and 92%). In this paper, each of the above new concepts is discussed separately and representative results are given for all.
In addition, new experimental results are reported on the combustion performance of HTPB loaded with low-energy polymer particles (item 1) and paraffine-based SDFS fuels (item 2).
Experimental
In a log plot, the slope of the regression rate straight line was evaluated according to Equation (1). The 2D radial burner is a laboratory-scale instrument and one of its advantages is the possibility of visual and direct observation of the hybrid combustion process. Other appropriate expressions of the solid fuel regression rate, for example, based on total mass flow as recommended in Reference [25], can also be implemented.
Since a large number of results were obtained as described above at SPLab and NUST, data processing in this work is performed using equation (1) based on the oxidant mass flux, as done in the vast majority of the literature.
Low-Energy Polymer Particles/HTPB
The morphological characteristics and diameter distribution of raw polymer particles were detailed by Confocal Laser Scanning Microscopy (CLSM, LEXT OLS3100, Olympus, Tokyo, Japan) on glass substrates; see Figure 3. In terms of cross-sectional diameters which were plotted as ˙r(t) vs.t, the 5% PE particle formulation shows a slightly improved regression rate compared to HTPB. This shows that the optimal addition of polymers is 5% PE particles (up to ≈21% increase) and 10% oleamide particles (up to ≈17% increase), despite the fact that the added polymer particles decrease the combustion performance in terms of energy released.
Excess PEG particles are more susceptible to melting, pyrolysis, and vaporization, resulting in reduced heat feedback to the HTPB surface, which slightly blocks the regression rate of HTPB and exposes the poor combustion properties of polymer particles.
Self-Disintegration Fuel Structure (SDFS)/Paraffin
Figure 11 illustrates the regression process for magnesium particles/paraffin composite fuels, and the arrows point to the burning Mg particles disintegrating from the paraffin matrix. Combustion surface regression process of small (top) and large (bottom) magnesium particles/paraffin composite fuels. The relationship between the regression rate and oxidizer mass flux of magnesium particles/paraffine composite fuels is illustrated in Figure 12.
The fitting results of rfvs.Gox for the two types of magnesium particles/paraffin composite fuels tested are shown in Table9.
Porous Layer Combustion Fuels
High Thermal Conductivity Fuels
The reason is the effect of the additives that increase the viscosity of the liquid molten paraffian, while stearic acid lowered the mixture melting point from 58.3◦C (pure paraffian) to 55.8◦C. To obtain a suitable paraffian-based fuel with both good mechanical properties and combustion performance, additives must be selected that do not increase the melt viscosity of the compound. Thus, the regression rate data of the tested paraffian-based fuels could be directly related to the viscosity of the corresponding liquid fuel samples and an increase in the liquid layer viscosity resulted in a decreased regression rate [32].
Comparison of two production techniques, simple ingredient blends or SDFS composites, for paraffin.
Concluding Remarks
The effect of high concentration of guanidinium azo-tetrazolate on thrust and specific impulse of a hybrid rocket. Effect of induced eddy current on regression rate of hybrid rocket fuel by helical grain configuration.Aerosp. Flame Visualization and Combustion Performance of Composite Energetic Particle Paraffin Based Fuels for Hybrid Rocket Propulsion.Int.
Effect of azodicarbonamide particles on the regression rate of hydroxyl-based polybutadiene-based (HTPB) propellants for hybrid rocket propulsion.
The Application of Computational
Thermo-Fluid-Dynamics to the Simulation of Hybrid Rocket Internal Ballistics with Classical or Liquefying
State of the Art of CFD Techniques for Rocket Internal-Ballistics Simulation
On the other hand, the fuel regression rate is a simulation result and proper fuel surface boundary conditions are required to allow its calculation. These are modeling, first, the formation, separation and introduction of the liquid layer on the surface of the fuel melt; and, secondly, the transformation of the molten fuel into a gaseous species that participates in the combustion process. In the following sections, the physical and numerical models developed by the authors for the calculation of the regression rate of classical and liquid fuels are presented, and a summary of the main results obtained in several test cases with the addition of experimental data is discussed.
First, the basic numerical framework is shown, and then the details of the different wall boundary management are reported.
Physical and Numerical Models 1. Governing Equations
The densities are then scaled with the values of the current pressure field in the system. A dedicated treatment of the mean mixture-fraction boundary condition at the fuel wall is also necessary. A parametric analysis of the effect of the entrainment parameter on the regression rate components is reported in reference [56].
Once equations (30)–(32) are combined, given the heat flow to the wall and the total mass flow, the three components of the fuel regression rate can be calculated.
Classical Polymeric Fuels: Numerical Results
The overall mix ratio, O/F, is the ratio of the average oxygen mass flow rate to the average fuel mass flow rate in the combustion; the latter was calculated as the fuel mass loss divided by the burn time. In addition, due to the decrease in mass flux, a decrease in the mean regression rate can be observed. The numerically predicted mean combustion efficiency is calculated by equation (44), taking into account the mean values of the chamber pressure and mass flow rates.
This feature can be explained by considering that the regression rate first decreases due to the reduction of the mass flow, then, due to the displacement of.
Paraffin-Based Fuels: Numerical Results
The details of the test campaign from which the experimental data were collected can be found in Reference [31]. In the second case, the entrainment parameter was assumed to be equal to 2.1×10−13m8.5s0.5/kg3; the latter is the one that provides the best fit of the experimental data obtained in test P4 as discussed in Reference [56]. This allows for the consideration of the dependence of the entrainment parameter on the average gas density as prescribed by Equation (33).
A detailed analysis of the deviation factors between calculated and measured pressure is addressed in Reference [56].
Conclusions
Basics of Hybrid Rocket Combustion and Propulsion; Kuo, K., Chiaverini, M., Eds.; AIAA of Progress in Astronautics and Aeronautics: Reston, VA, USA, 2007; Volume 218, pp. Effect of Grain Port Length-Diameter Ratio on Combustion Performance in Hybrid Rocket Engines. Acta Astronaut. Basics of Hybrid Rocket Combustion and Propulsion; Kuo, K., Chiaverini, M., Eds.; AIAA Advances in Astronautics and Aeronautics: Reston, VA, USA, 2007; Volume 218, p.
Switch between paraffin-based and aluminum-loaded HTPB fuels to improve performance of hybrid rocket fed with N2O.Aerosp.
Theoretical Investigation on Feedback Control of Hybrid Rocket Engines
Discussion
Error propagation analysis is performed to study the impact and significance of measurement errors on thrust and mixture ratio control. Depending on the RBS parameters and the type of governing law, 5 to 7.5 s were needed to reach the thrust target in the simulations. Simulations were performed to analyze the influence of the radial distance of the sensors between the resistors.
Knowledge of combustion efficiency could be considered in the regulation law.
Conclusions
In Proceedings of the 9th International Symposium on Combustion, New York, NY, VS, 27 augustus - 1 september 1962;. In Proceedings of the 7th European Conference for Aeronautics and Space Sciences (EUCASS), Milaan, Italië, 3–6 juli 2017. In Proceedings of the 5th European Conference for Aeronautics and Space Sciences (EUCASS), München, Duitsland, 1–5 juli 2013.
I Proceedings of the 5th European Conference for Aeronautics and Space Sciences (EUCASS); München, Tyskland, 1.-5. juli 2013.
Review of Classical Diffusion-Limited Regression Rate Models in Hybrid Rockets
- Physical Processes in Hybrid Rockets
- Marxman’s Diffusion-Limited Model
- Radiation
- Other Non-Ideal Considerations
- Kinetics-Limited Models
- Summary
This location is about 10-20% of the boundary layer thickness (δ) of the wall and can be about 0.1δ thick [5]. Increasing the flow rate of the oxidizer improves the convective heat transfer to the wall and thus the vaporization rate of the fuel. For the equi-diffusive case, the bubble parameter also turns out to be a similarity parameter of the boundary layer.
Finally, combining equation (A20) with equation (A11) leads to an expression for the blowing correction in terms of the blowing parameter, esp.
Small-Scale Static Fire Tests of 3D Printing Hybrid Rocket Fuel Grains Produced from Different Materials
Methodology 1. Material Selection
A series of ABS pellets were printed using a Prusa i3 MK2 FDM 3D printer (Prusa Research s.r.o., Prague, Czech Republic) which was used to verify the operation of the test stand and small-scale motor case. These initial tests also allowed the data logger code to be tested and modified as required, and to verify the correct operation of the sensors. The fuel pellets of the seven different materials were then subjected to a single burn of three seconds each.
These measurements made it possible to determine the fuel and oxidant and total mass flow rates, the O/F ratio and the fuel regression rate.
Results 1. Testing
It was observed that the fuel port radius of the ASA bead increased by the greatest amount. The regression rate of ABS fuel grain was one of the lowest of the materials tested. Inspection of Figure 5 also shows that combustion in the AL fuel grain did not occur at the beginning of the combustion port.
It was speculated that the poor performance of the AL fuel grain was largely due to the size, shape and surface area of aluminum particles.
