Baltic State Technical University

About: Baltic State Technical University is a education organization based out in Saint Petersburg, Russia. It is known for research contribution in the topics: Laser & Combustion. The organization has 581 authors who have published 539 publications receiving 1929 citations.

Burning of Nano-Aluminized Composite Rocket Propellants

Abstract: Several aluminum nanopowders were examined and compared with the final goal to evaluate their application in solid rocket propulsion. A detailed investigation of pre-burning properties by the Brunauer-Emmet-Teller method, electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy was carried out. Ballistic properties and the combustion mechanism of several aluminized propellant formulations were investigated. In particular, aggregation and agglomeration of metal particles at and near the burning surface were analyzed by high-speed high-resolution color digital video recordings. All tested nano-powders are of Russian production; their physical characterization was carried out at the Istituto Donegani (Novara, Italy); ballistic studies were performed at the Solid Propulsion Laboratory (Milano, Italy) using laboratory and, for comparison, industrial composite propellants based on ammonium perchlorate as an oxidizer. Results obtained under a fair variety of operating conditions typical of rocket propulsion indicate, for increasing nano-Al mass fraction or decreasing nano-Al size, larger steady burning rates with essentially the same pressure sensitivity. While aggregation and agglomeration phenomena still occur, their significance may be reduced by using nano-Al instead of micro-Al.

Condensed Combustion Products at the Burning Surface of Aluminized Solid Propellant

Abstract: Experimental results are presented on the formation of condensed combustion products (CCPs) at the burning surface of aluminized solid propellants. A number of experimental techniques were developed for describing the characteristics of the CCPs as a function of the oxidizer particle size and pressure. The results of this investigation provide qualitative descriptions of the CCPs formed at the propellant burning surface as functions of oxidizer particle size and pressure. Nomenclature ak = oxidizing potential of gas mixture (mole share of oxidizing components in the mixture) D = diameter of agglomerate D43 = mass-medium diameter of agglomerates D AP = mass-medium diameter of ammonium perchlorate particles d = diameter of e ne oxide particle d HDO 43 = mass-medium diameter of e ne oxide particles Fm.D/ = mass function of agglomerate size distribution fm.D/ = mass function of agglomerate size distribution density fm.d/ = mass function of e ne oxide particle size distribution density P = pressure r = propellant burn rate T = temperature Zm = share of unburned metal in the agglomerates relative to the initial aluminum in the propellant Z a = share of initial metal in the propellant used to form the agglomerates as a whole Z HDO = share of initial metal in the propellant used to form the e ne oxide particles Z ox = share of initial metal in the propellant used to form oxide in the agglomerates ° = edge angle of wetting ´ = mass share of oxide in agglomerates

Microstructure Effects in Aluminized Solid Rocket Propellants

Abstract: Experiments concerning the ballistic characterization of several nanoaluminum (nAl) powders are reported. Most studies were performed with laboratory composite solid rocket propellants based on ammonium perchlorate as oxidizer and hydroxyl-terminated polybutadiene as inert binder. The ultimate objective is to understand the flame structure of differently metallized formulations and improve their specific impulse efficiency by mitigating the two-phase losses. Ballistic results confirm, for increasing nAl mass fraction or decreasing nAl size, higher steady burning rates with essentially the same pressure sensitivity and reduced average size of condensed combustion products. However, aggregation and agglomeration phenomena near the burning surface appear noticeably different for microaluminum (μAl) and nAl powders. By contrasting the associated flame structures, a particle-laden flame zone with a sensibly reduced particle size is disclosed in the case of nAl. Propellant microstructure is considered the main controlling factor. A way to predict the incipient agglomerate size for μAl propellants is proposed and verified by testing several additional ammonium perchlorate/hydroxyl-terminated polybutadiene/aluminum formulations of industrial manufacture.

Model of aluminum agglomerate evolution in combustion products of solid rocket propellant

Abstract: A mathematical model was developed for agglomerate evolution in the combustion products of solid rocket propellant. The model is based on the principle of dividing the complex process into relatively simple phenomena with sequential synthesis of their descriptions. The model includes description of many processes observed experimentally. They are 1 ) metal combustion, 2 ) chemical interaction between metal and oxide in agglomerates, 3) change in structure of agglomerates, and 4 ) interaction of agglomerates and carrier e ow. Quite high quality of the model was proved by satisfactory agreement between calculation results and experimental data.