Experimental and theoretical study on characteristics of pulse excitation in T-burners

Abstract

Pulse excitation is the key to measure the pressure-coupling response function of composite propellant. It is also a key trigger factor for nonlinear combustion instability. This paper aims at understanding characteristics of pulse excitation in T-burners. Pulse excitation is provided by black powder (BP). D 2 law is used to calculate BP burning properties. Firstly, the experimental pressure history of a pulse excitation is analyzed. Pressure pulse and mean pressure increment are introduced to describe pulse excitation. Secondly, the modified zero-dimension model and one-dimension model of pressure pulse are established based on energy conservation and modification. The results of models indicate that the modified zero-dimensional model can accurately predict the pressure pulse. The modified zero-dimension model demonstrates that the pressure pulse is determined by pulse build-up time threshold, volume coefficient, effective weight fraction of BP, weight of BP et. al. When burning time of BP is larger than the threshold, volume coefficient is equal to 2, and effective weight fraction of BP is less than 1. The pressure pulse is approximately linear correlation with weight and effective weight fraction of BP. Otherwise, volume coefficient is larger than 2, and effective weight fraction of BP is equal to 1. The pressure pulse is approximately linear correlation with volume coefficient and BP weight. Thirdly, a zero-dimensional prediction model of mean pressure is established based on conservations of energy and mass. The prediction models of pressure pulse and mean pressure are validated by T-burner experiments. Finally, effects of BP burning properties on pressure pulse and mean pressure increment are studied. The results show that both pressure pulse and mean pressure increment increase with increasing BP weight, linearly. The pressure pulse is more sensitivity to the variations of burning time of BP. As burning time of BP decreases, the mean pressure increment gradually increases to the maximum, and the pressure pulse can become a very large value.

Multi‐Anion Intercalated Layered Double Hydroxide Nanosheet‐Assembled Hollow Nanoprisms with Improved Pseudocapacitive and Electrocatalytic Properties

“…The broad band from 3522 to 3409 cm −1 was due to the O−H stretching vibration of ‐OH and interlayer H 2 O . The band at 1614 cm −1 could be ascribed to the bending mode of O−H vibration . The bands at 645 and 471 cm −1 was related to Co−O and Ni−O stretching vibrations, respectively, further verifying the formation of NiCo‐LDH .…”

“…The SC performance of NiCo‐LDH HNP was compared with recent reported NiCo‐based electrodes in three‐electrode system (Table S1), where one can find that NiCo‐LDH HNP delivers a very high specific capacitance and excellent rate and cycling performance, rendering it a very promising electrode material for energy storage application. This outstanding electrochemical performance should come from the combined effect of unique morphology of the nanosheet‐assembled HNP and enlarged lamellar spacing of the LDH by multi‐anion intercalation.…”

“…In parallel to these strategies, nanostructured engineering has been proven to be an effective approach to further boost the electrochemical performance of materials by increasing the exposure of electroactive sites, enhancing the mass and charge transport, and alleviating the volume change and particle aggregation during redox reactions . Especially, hollow architectures with well‐defined curvature in the nanoscale range are of great interest because they are expected to expose more edge sites under imposed geometric constraints in addition to other merits of low mass density, shell permeability, and large surface area . Although remarkable progress has been made in the synthesis of LDHs for electrochemical applications, co‐engineering of the hollow nanostructures and anion intercalation of a given LDH for enhanced SC and OER performance remains largely unexplored so far …”

Amorphous Core–Shell Nanoparticles as a Highly Effective and Stable Battery‐Type Electrode for Hybrid Supercapacitors

“…The bands at 1147 and 1017 cm −1 are due to the SO 4 2− and HSO 4 − vibrations, which are came from the added Na 2 S 2 O 3 in the coordination etching . For low wavenumber region, the bands at 665 and 527 cm −1 can be caused by the stretching vibration of M–O and M–OH (M = Ni and Co) bonding . Furthermore, the formation of hydroxides can also be demonstrated by comparison with the FTIR spectra (Figure S4, Supporting Information) of as‐prepared Ni–Co hydroxides (NCLDH) with good crystallization.…”

Flexible and Mechanically Durable Asymmetric Supercapacitor Based on NiCo‐Layered Double Hydroxide and Nitrogen‐Doped Graphene Using a Simple Fabrication Method

“…It was clearly seen that with an increasing scan rate, the positions of the anodic and cathodic peaks shifted slightly to the more positive and negative directions, respectively, which is attributed to the internal resistance of electrode materials . The comparison of CV curves of the NiCo LDH@NG/CC and NiCo LDH/CC electrodes at 5 mV s −1 (Figure a,b and Figure S3a, Supporting Information) indicated that the deposition of NG as an intermediate layer between CC and NiCo LDH led to a slight increase in current and also enlargement in the area under the CV curve.…”