Experimental investigation of the combustion products in an aluminised solid propellant

In order to understand the ignition and combustion characteristics of NEPE propellants under different pressure conditions and the agglomeration behavior of aluminum particles on the burning surface, the Al/NEPE propellant was tested on a sealed high-pressure laser ignition platform. Laser ignition experiments show that both ignition delay time and combustion time are inversely proportional to ambient pressure. With the increase of pressure, the reduction of ignition delay time and self-sustaining combustion time is reduced. The impact of pressure on ignition and combustion is very complex. We then analyze the effect of pressure on ignition delay time using a theoretical mechanism. High-speed microscopic images display the agglomeration of aluminum particles in propellants mainly through the following three processes: accumulation, aggregation, and agglomeration. It is also found that many aluminum particles are agglomerated on the surface, the aluminum droplet agglomerates formed on the combustion surface are separated from the combustion surface, and the agglomerates rupture and flow out of the liquid alumina during the combustion process. The phenomenon of secondary agglomeration is also observed. The microstructure and elemental composition of combustion products of aluminum particles in NEPE propellant were obtained by scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). The detection results confirmed some agglomeration phenomena. At 3.0 MPa, the combustion of the propellant sample is sufficient, and the aluminum particles are smooth spherical alumina particles. At 1.0 MPa, the combustion of the propellant sample is insufficient, and the aluminum particles are rough. The particle size under different pressure was analyzed by a laser particle size analyzer. The results show that increasing the pressure can reduce the average agglomeration size of aluminum particles and improve combustion efficiency. The number of large particle aggregates is more at 3 MPa. From the perspective of overall particle size results, within the same diameter interval, the percentage of particle number does not increase or decrease significantly with the increase of pressure.

Section: Introductionmentioning

confidence: 99%

Experimental Investigation on Combustion Characteristics and Agglomeration of Al/NEPE Propellants

Zhang

Feng³

et al. 2021

“…To ensure uniform ignition, a conventional nichrome wire was used to ignite the samples. The burning rates of samples under 3 MPa, 5 MPa, 7 MPa and 9 MPa were measured by the measuring system [23,24] at room temperature. And to obtain burning rate accurately, the burning data in first 5 mm and last 5 mm were omitted.…”

Section: Characterization Of Burning Propertiesmentioning

confidence: 99%

Study on Burning and Thermal Decomposition Properties of HTPB Propellant Containing Synthesized Micro‐nano Ferric Perfluorooctanoate

Zhen

Zhou

Wang

et al. 2019

A novel micro‐nano ferric perfluorooctanoate [Fe(PFO)3] was prepared and added in AP/Al/HTPB composite solid propellant as a catalyst to study its effects on burning and thermal decomposition properties of the propellant. To further discuss the possible thermal mechanism of the propellant containing Fe(PFO)3, the major effects of Fe(PFO)3 catalyst on Al were investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TG) and X‐ray diffraction (XRD). Results show that By adding 3 w.t.% Fe(PFO)3, the burning rate could increase by 27.8 % at 3 MPa, meanwhile, the pressure exponent decreased. The aggregation/agglomeration process of the propellant containing Fe(PFO)3 efficiently suppressed, and the particle size of condensed combustion products decreased clearly. In addition, Fe(PFO)3 could reduce the thermal decomposition temperature of the propellant and enhance the heat release. Thermite reaction between decomposition products of Fe(PFO)3 and Al was triggered at 635 °C, resulting in heat release and formation of α‐Al2O3.

“…With the increasing energy density and specific impulse in solid rocket motors, improved solid propellants are always required. Many researchers have already studied the physical, chemical, mechanical, thermal, and combustion properties of such solid propellants [1][2][3][4][5]. Nitrate ester plasticised polyether (NEPE) propellants, a new generation of high-energy solid propellants, have become a research focus: they make use of polyethers, such as polyethylene glycol (PEG) or ethylene oxideÀ tetrahydrofuran (PET) co-polyether, as a binder.…”

Section: Introductionmentioning

confidence: 99%

A Study on Consumption and Characterization of Stabilizer Content of NEPE Propellant via FTIR

Tao

Sui

et al. 2019

Self Cite

Nitrate ester plasticised polyether (NEPE) propellants, a kind of high‐energy solid propellant, were tested for their stabilizer content and Fourier transform infrared spectrum (FTIR) to study their ageing performance. On the one hand, a stabilizer consumption equation containing the ageing temperature, stabilizer content, and ageing time was established by analyzing the data of stabilizer content of NEPE aged at high temperatures (328, 333, 338, 343, 348, and 353 K). On the other hand, it was found that the second derivative spectral absorbance of 1598 cm−1 has a high linear correlation to the stabilizer content of NEPE propellant, and an equation, which can be used to calculate the stabilizer content of NEPE with FTIR data, was established. Thereafter, to prove the universality and accuracy of these two equations, FTIR testing of NEPE aged at room temperature (298 K) was carried out. Accordingly, the two other equations for stabilizer consumption at room temperature were derived by the FTIR data and the stabilizer consumption equation, respectively. They were consistent and the universality and accuracy of these equations were proven, and the feasibility of non‐destructive monitoring methods for NEPE propellants via FTIR was experimentally verified.