Effect of ITE and nozzle exit cone erosion on specific impulse of solid rocket motors
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Solid-fuel rocket
Specific impulse
Cone (formal languages)
Rocket (weapon)
Based on telemetry visual acceleration,the calculation models of thrust and specific impulse were established,and the effect of the additional mass on the thrust was taken into account.The thrust and specific impulse of solid rocket motor during flight process were calculated by using the model.The calculated results were compared with re-predicted results by standard internal ballistic program.Two kinds of calculation results are consistent.The calculation examples show that the model is available and practicable,and the method can be used for correctly reconstructing real-time thrust and specific impulse,which is applicable for rapid analysis and assessment of solid rocket motor flight test results.
Specific impulse
Solid-fuel rocket
Rocket (weapon)
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Hybrid rocket engines (HREs) are a chemical propulsion system that nominally combine the advantages of liquid-propellant rocket engines (LREs) and solid-propellant rocket motors (SRMs). HREs in some cases can have a higher specific impulse and better controllability than SRMs, and lower cost and engineering complexity than LREs. For HREs and SRMs, both kinds of rocket engine employ a solid fuel grain, and the chosen grain configuration is a crucial point of their design. Different grain configurations have different internal ballistic behavior, which in turn can deliver different engine performance. A cylindrical grain design is a very common design for SRMs and HREs. A non-cylindrical-grain is a more complex grain configuration (than cylindrical) that has been used in many SRMs, and is also a choice for some HREs. However, while an HRE and an SRM can employ the same fuel grain configuration, the resulting internal ballistic behavior would not be expected to be the same. Pressure-dependent burning tends to dominate in SRMs, while axial flow-dependent burning tends to dominate in HREs. To help demonstrate in a more direct manner the influence of the differing combustion processes on the same fuel grain configuration used by an HRE and SRM, a number of internal ballistic simulations are undertaken for the present study. For the reference SRM cases looked at, an internal ballistic simulation program that has the capability of predicting head-end pressure and thrust as a function of time into a simulated firing is utilized for the present investigation; for the corresponding HRE cases, a simulation program is used to simulate the burning and flow process of these engines. For the present investigation, the two simulation programs are used to simulate the internal ballistic performance of various HREs and SRMs employing comparable cylindrical and non-cylindrical fuel grain configurations. The predicted performance results, in terms of pressure and thrust, are consistent with expectations that one would have for both propulsion system types.
Specific impulse
Solid-fuel rocket
Internal ballistics
Rocket (weapon)
Internal flow
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Specific impulse
Solid-fuel rocket
Agglomerate
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The digital simulation method of internal ballistic properties of solid rocket motor is studied, including determining its random variables, modifying the theoretical formulation for correcting pressure and thrust based on the tested data and deriving the simulation mathematic model. The method can be used for the scheme selection, performance estimation and flow field computation of solid motor. On the basis of the digital simulation of internal ballistic properties for a solid rocket motor, the mean value and variance of internal ballistic properties are given, such as, average pressure and thrust, maximum pressure, specific impulse and total impulse. The results of simulation agree well with test data, showing that the digital simulation model of internal ballistic properties of solid rocket motor is reliable.
Solid-fuel rocket
Specific impulse
Internal ballistics
Internal flow
Internal pressure
Rocket (weapon)
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According to the characteristic of electric thruster,the expressions and units of the specific impulse of electric thruster under SI units are introduced. Linked to the application of electric propulsion system in spacecraft,the effects of various factors on the optimum specific impulse and the selecting of the specific impulse of electric thruster are discussed.
Specific impulse
Impulse generator
Ion thruster
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Hybrid rocket engines (HREs) are a chemical propulsion system that nominally combine the advantages of liquid-propellant rocket engines (LREs) and solid-propellant rocket motors (SRMs). HREs in some cases can have a higher specific impulse and better controllability than SRMs, and lower cost and engineering complexity than LREs. For HREs and SRMs, both kinds of rocket engine employ a solid fuel grain, and the chosen grain configuration is a crucial point of their design. Different grain configurations have different internal ballistic behavior, which in turn can deliver different engine performance. A cylindrical grain design is a very common design for SRMs and HREs. A non-cylindrical-grain is a more complex grain configuration (than cylindrical) that has been used in many SRMs, and is also a choice for some HREs. However, while an HRE and an SRM can employ the same fuel grain configuration, the resulting internal ballistic behavior would not be expected to be the same. Pressure-dependent burning tends to dominate in SRMs, while axial flow-dependent burning tends to dominate in HREs. To help demonstrate in a more direct manner the influence of the differing combustion processes on the same fuel grain configuration used by an HRE and SRM, a number of internal ballistic simulations are undertaken for the present study. For the reference SRM cases looked at, an internal ballistic simulation program that has the capability of predicting head-end pressure and thrust as a function of time into a simulated firing is utilized for the present investigation; for the corresponding HRE cases, a simulation program is used to simulate the burning and flow process of these engines. For the present investigation, the two simulation programs are used to simulate the internal ballistic performance of various HREs and SRMs employing comparable cylindrical and non-cylindrical fuel grain configurations. The predicted performance results, in terms of pressure and thrust, are consistent with expectations that one would have for both propulsion system types.
Specific impulse
Solid-fuel rocket
Internal ballistics
Rocket (weapon)
Internal flow
Rocket engine
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Abstract : A mathematical model of a small solid propellant rocket was programmed for use with a Univac Solid State 90 digital computer by means of Fortran I and Fortran II. In addition to calculating the pressure-time and thrust-time transients, the program computes time-averaged pressure, thrust coefficient, thrust, flow rate, and burning rate, as well as total impulse and specific impulse. The report includes the derivation of equations, the method of solution, the program in Fortran I and Fortran II, an example solution compared with experiment, and a recommended procedure for use of the computer program in the design and development of a small solid propellant rocket motor.
Solid-fuel rocket
Rocket (weapon)
Rocket propellant
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The aim of this research is to examine the effects of propellant properties such as: combustion temperature, propellant density, characteristic velocity, reference burning rate and burning rate pressure exponent on internal ballistic performance of solid rocket motors. A zero dimensional internal ballistic solver is developed and internal ballistic performance analyses of solid rocket motors having slotted cross section are performed. Thus, different internal ballistic results such as maximum combustion pressure, burning time, specific impulse and total impulse are determined. Finally, variation of these response variables according to solid propellant properties are determined constructing different response surfaces. Graphical results represented in this work makes easier to select solid propellants for a certain kind of geometrical configuration.
Specific impulse
Solid-fuel rocket
Internal ballistics
Burn rate (chemistry)
Internal pressure
Rocket (weapon)
Ballistics
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Aluminum is used in the rocket industry primarily because it increases the specific impulse of the rocket motor. However, the combustion of aluminum sometime leads to various disadvantages such as slag accumulation and two-phase losses in the rocket motor. This study attempts to mechanically activate the aluminum using PTFE (polytetrafluoroethylene) and improve its ballistic performance in solid and hybrid rockets. This investigation established through various tests (such as thermogravimetric analysis [ TGA ], differential calorimeter [ DSC ], particle size analysis, scanning electron microscope [SEM] analysis, viscosity measurements, and other tests) that this mechanically activated aluminum is suitable for replacing regular aluminum in composite solid propellants. A significant improvement in the burn rate of solid propellant and reduction in the agglomeration of aluminum was observed when mechanically activated aluminum was incorporated in the composition. The solid propellant composition prepared with this mechanical activation of aluminum was also incorporated in a study where the characteristic of high burn rates of this composition can be used in an end burning grain configuration to increase the payload capacity of the Pegasus launch vehicle. This study also found that with the addition of this mechanically activated aluminum in hybrid rocket fuel grain, the ballistic performance (specific impulse, density specific impulse, combustion efficiency, regression rates, etc.) improved significantly in the hybrid rocket motor. The addition of mechanically activated aluminum in solid and hybrid rockets makes the system more compact by increasing the density-specific impulse of the rocket motor.
Solid-fuel rocket
Specific impulse
Thermogravimetric analysis
Solid fuel
Rocket (weapon)
Rocket propellant
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A modular computer program for prediction of internal ballistic performances of solid propellant rocket motors SPPMEF has been developed. The program consists of following modules: TCPSP (Calculation of thermo-chemical properties of solid propellants), NOZZLE (Dimensioning of nozzle and estimation of losses in rocket motor), GEOM (This module consists of two parts: a part for dimensioning the propellant grain and a part for regression of burning surface) and ROCKET (This module provides prediction of an average delivered performance, as well as mass flow, pressure, thrust, and impulse as functions of burning time). Program is verified with experimental results obtained from standard ballistic rocket test motors and experimental rocket motors. Analysis of results has shown that established model enables has high accuracy in prediction of solid propellant rocket motors features in cases where influence of combustion gases flow on burning rate is not significant.
Specific impulse
Solid-fuel rocket
Rocket (weapon)
Dimensioning
Characteristic velocity
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