Analysis of acoustic pressure oscillation during vented deflagration and proposed model for the interaction with the flame front

2017 ◽  
Vol 42 (11) ◽  
pp. 7707-7715 ◽  
Author(s):  
M. Schiavetti ◽  
M. Carcassi
Keyword(s):  
Flame Front ◽  
Acoustic Pressure ◽  
Pressure Oscillation ◽  
Proposed Model

scholarly journals Investigation on Acoustic Properties of Thruster Chamber with Coaxial Injectors and Plenum Chamber

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Dekun Gao ◽  
Jianxiu Qin ◽  
Huiqiang Zhang
Keyword(s):  
Acoustic Pressure ◽  
Rocket Engine ◽  
Pressure Oscillation ◽  
Acoustic Mode ◽  
Acoustic Properties ◽  
Pressure Oscillations ◽  
Plenum Chamber ◽  
Model Chamber ◽  
Pressure Peak ◽  
Tuning Frequency

Based on the URANS equation, a numerical simulation is carried out for acoustic properties of the thruster chamber with coaxial injectors and plenum chamber in a liquid rocket engine. Pressure oscillations with multiacoustic modes are successfully excited in the chamber by using the constant volume bomb method. FFT analysis is applied to obtain the acoustic properties of eigenfrequencies, power amplitudes, and damping rates for each excited acoustic mode. Compared with the acoustic properties in the model chamber with and without an injector as well as with and without the plenum chamber, it can be found that the injector with one open end and one half-open end still can work as a quarter-wave resonator. The power amplitudes of the acoustic mode can be suppressed significantly when its eigenfrequency is close to the tuning frequency of the injector, which is achieved by Cutting down the pressure Peak and Raising up the pressure Trough (CPRT). Compared with the acoustic properties in the model chamber with and without the plenum chamber, it can be found that 1L acoustic pressure oscillation is inhibited completely by the plenum chamber and other acoustic pressure oscillations are also suppressed in a different extent. The injector and plenum chamber have a little effect on the eigenfrequencies and damping rate of each acoustic mode. For multimode pressure oscillation, it is better for tuning frequency of the injector closing to the lower eigenfrequency acoustic mode, which will be effective for suppression of these multiacoustic modes simultaneously.

Acoustic pressure oscillation effects on mean burning rates of plateau propellants

2021 ◽  
Vol 226 ◽  
pp. 69-86
Author(s):  
B. Kathiravan ◽  
C. Senthilkumar ◽  
Rajendra Rajak ◽  
K. Jayaraman
Keyword(s):  
Acoustic Pressure ◽  
Pressure Oscillation ◽  
Burning Rates

SIMULATION OF THE GAS MIXING PROCESS OF THE FUEL SUPPLY SYSTEM

2020 ◽  
Vol 13 (1) ◽  
pp. 87-93
Author(s):  
Roman Shtykov
Keyword(s):  
Flame Front ◽  
Theoretical Data ◽  
Supply System ◽  
Turbulent Jet ◽  
Mixing Process ◽  
Gas Mixing ◽  
Complete Combustion ◽  
Proposed Model ◽  
Combustible Gases ◽  
Combustion Processes

The article discusses the methods of modeling gas mixing, leading to more intense gas mixing, for the most complete combustion of the resulting turbulent jet, which is used in combustion processes. The necessity of the proposed model is proved: by summing the concentrations of the components in the zones of fuel and oxidizer; stoichiometric flow of combustible gases and oxygen (air) to the flame front, resulting from the dynamic compatibility of indicators at a weak gap; comparison of numerical results with experimental and theoretical data on the combustion of a mixture in air.

scholarly journals Effect of the inner-surface baffles on the tangential acoustic mode in the cylindrical combustor

Open Physics ◽  
2020 ◽  
Vol 18 (1) ◽  
pp. 1215-1222
Author(s):  
Runze Duan ◽  
Yifan Cao ◽  
Hongbin Duan ◽  
Liang Tian ◽  
Liting Tian ◽  
...  
Keyword(s):  
Acoustic Pressure ◽  
Combustion Instability ◽  
Pressure Oscillation ◽  
Acoustic Mode ◽  
Second Order ◽  
Propulsion System ◽  
Combustion Instabilities ◽  
First Order ◽  
Inner Surface ◽  
Eigen Frequency

Abstract The combustion instability in a propulsion system is a ubiquitous problem. The radial baffles usually installed on the injector faceplate eliminate the combustion instability (acoustic pressure oscillation) in the propulsion system. In this article, the longitudinal baffles are installed on the inner surface of the combustor wall to control the combustion instabilities. The first-order and second-order tangential modes are induced in the experiments. The effects of the parameters of the baffle on the acoustic pressure oscillation in the cylindrical combustor are investigated. The effect of the combustor nozzle on the tangential modes has been systematically investigated. It is concluded that the eigen-frequency and amplitude of the first-order tangential mode decline with the increase in the longitudinal baffle number and height. For the second-order tangential mode, the eigen-frequency and amplitude monotonically increase until a maximum value (four baffles), subsequently decrease with the increase in the baffle number and height. The combustor without the nozzle obtains a lower frequency than that with the nozzle, especially for the low baffle height in the combustor.

Structure and Interaction of Protamine by Dark Field Electron Microscopy

1976 ◽  
Vol 34 ◽  
pp. 160-161
Author(s):  
D.P. Bazett-Jones ◽  
F.P. Ottensmeyer
Keyword(s):  
Electron Microscopy ◽  
Dark Field ◽  
Amino Acid Sequences ◽  
Dimensional Structure ◽  
3 Dimensional ◽  
Field Electron ◽  
Proposed Model ◽  
Field Electron Microscopy ◽  
Dark Field Electron ◽  
Positively Charged

It has been shown for some time that it is possible to obtain images of small unstained proteins, with a resolution of approximately 5Å using dark field electron microscopy (1,2). Applying this technique, we have observed a uniformity in size and shape of the 2-dimensional images of pure specimens of fish protamines (salmon, herring (clupeine, Y-l) and rainbow trout (Salmo irideus)). On the basis of these images, a model for the 3-dimensional structure of the fish protamines has been proposed (2).The known amino acid sequences of fish protamines show stretches of positively charged arginines, separated by regions of neutral amino acids (3). The proposed model for protamine structure (2) consists of an irregular, right-handed helix with the segments of adjacent arginines forming the loops of the coil.

The Influence of Cognitive and Affective Reactions to Feedback on Subsequent Goals

2010 ◽  
Vol 15 (2) ◽  
pp. 121-131 ◽  
Author(s):  
Remus Ilies ◽  
Timothy A. Judge ◽  
David T. Wagner
Keyword(s):  
Performance Feedback ◽  
Business School ◽  
Structural Equation ◽  
Emotional Reactions ◽  
Equation Model ◽  
Proposed Model ◽  
And Performance ◽  
Dispositional Measure ◽  
The Relationship ◽  
Reactions To Feedback

This paper focuses on explaining how individuals set goals on multiple performance episodes, in the context of performance feedback comparing their performance on each episode with their respective goal. The proposed model was tested through a longitudinal study of 493 university students’ actual goals and performance on business school exams. Results of a structural equation model supported the proposed conceptual model in which self-efficacy and emotional reactions to feedback mediate the relationship between feedback and subsequent goals. In addition, as expected, participants’ standing on a dispositional measure of behavioral inhibition influenced the strength of their emotional reactions to negative feedback.

Decision making based on intuitionistic fuzzy preference relations with additive approximate consistency

2020 ◽  
Vol 39 (3) ◽  
pp. 4041-4058
Author(s):  
Fang Liu ◽  
Xu Tan ◽  
Hui Yang ◽  
Hui Zhao
Keyword(s):  
Decision Making ◽  
Decision Makers ◽  
Real Interval ◽  
Preference Relations ◽  
Intuitionistic Fuzzy ◽  
Proposed Model ◽  
Fuzzy Preference Relations ◽  
Novel Concept ◽  
Fuzzy Weights ◽  
Fuzzy Preference

Intuitionistic fuzzy preference relations (IFPRs) have the natural ability to reflect the positive, the negative and the non-determinative judgements of decision makers. A decision making model is proposed by considering the inherent property of IFPRs in this study, where the main novelty comes with the introduction of the concept of additive approximate consistency. First, the consistency definitions of IFPRs are reviewed and the underlying ideas are analyzed. Second, by considering the allocation of the non-determinacy degree of decision makers’ opinions, the novel concept of approximate consistency for IFPRs is proposed. Then the additive approximate consistency of IFPRs is defined and the properties are studied. Third, the priorities of alternatives are derived from IFPRs with additive approximate consistency by considering the effects of the permutations of alternatives and the allocation of the non-determinacy degree. The rankings of alternatives based on real, interval and intuitionistic fuzzy weights are investigated, respectively. Finally, some comparisons are reported by carrying out numerical examples to show the novelty and advantage of the proposed model. It is found that the proposed model can offer various decision schemes due to the allocation of the non-determinacy degree of IFPRs.

A study of practice based design research models from knowledge integration perspective

2019 ◽  
Vol 1 (1) ◽  
Author(s):  
Honghai LI ◽  
Jun CAI
Keyword(s):  
Knowledge Production ◽  
Theoretical Basis ◽  
Knowledge Integration ◽  
Design Research ◽  
Research Process ◽  
Two Dimensions ◽  
Design Knowledge ◽  
Research Projects ◽  
Proposed Model ◽  
Design Innovation

The transformation of China's design innovation industry has highlighted the importance of design research. The design research process in practice can be regarded as the process of knowledge production. The design 3.0 mode based on knowledge production MODE2 has been shown in the Chinese design innovation industry. On this cognition, this paper establishes a map with two dimensions of how knowledge integration occurs in practice based design research, which are the design knowledge transfer and contextual transformation of design knowledge. We use this map to carry out the analysis of design research cases. Through the analysis, we define four typical practice based design research models from the viewpoint of knowledge integration. This method and the proposed model can provide a theoretical basis and a path for better management design research projects.

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