Frequency and Pressure Characteristics of a Helmholtz-Type Valveless Self-Excited Pulse Combustor

2012 ◽  
Vol 455-456 ◽  
pp. 161-167 ◽  
Author(s):  
Yan Ying Xu ◽  
Ming Zhai ◽  
Peng Dong ◽  
Fei Wang ◽  
San Long Peng ◽  
...  
Keyword(s):  
Heat Load ◽  
Maximum Pressure ◽  
Pressure Amplitude ◽  
Operating Characteristics ◽  
Pulse Combustor ◽  
Excess Air ◽  
Supply Mode ◽  
Flame Sheet ◽  
The Mathematical Model ◽  
Pressure Characteristics

The frequency and pressure characteristics of a Helmholtz-type valveless self-excited pulse combustor with continuous supply of fuel and air are investigated in this paper. A theoretical model of combustion is established. In the model, combustion is assumed to take place in a thin flame sheet separating the two zones, and the effects of the continuous gas-supply mode and heat transfer of the tailpipe on the operating characteristics are considered. From the mathematical model, the expressions of frequency and maximum pressure amplitude for the pulse combustor are derived. The results suggest that the frequency decreases with the increase of excess air ratio and tailpipe length, and increases with the heat load. The pressure amplitude increases with the increase of the excess air ratio and heat load, and slightly declines with the increase of the tailpipe length. The experimental data show qualitative agreement with the calculated results.

Frequency Characteristics of the Valveless Self-Excited Pulse Combustor of Bend Tailpipe Helmholtz Type

2014 ◽  
Vol 525 ◽  
pp. 232-235 ◽  
Author(s):  
Yan Ying Xu ◽  
Jian Chen ◽  
Ruo Jun Wang
Keyword(s):  
Heat Load ◽  
Frequency Characteristics ◽  
Pulse Combustor ◽  
Excess Air

The frequency characteristics of the valveless self-excited pulse combustor of bend tailpipe Helmholtz type with continuous supply of gas and air were investigated by experiment in this paper. The effects of bend tailpipe structure, heat load and the excess air ratio on the frequency of operation were studied. The results show that the frequency of operation decreases with the increase of tailpipe bent angle and the frequency is relatively low with the bent position at tailpipe entrance. The frequency is increased with the increase of heat load, and decreased with the excess air ratio.

Effect of Chemical Hythane Composition on Pressure in Combustion Chamber of Engine

2019 ◽  
pp. 36-42
Author(s):  
A. P. Shaikin ◽  
I. R. Galiev
Keyword(s):  
Natural Gas ◽  
Combustion Chamber ◽  
Power Plants ◽  
Engine Speed ◽  
Combustion Engine ◽  
Fuel Mixture ◽  
Maximum Pressure ◽  
Chamber Volume ◽  
Excess Air ◽  
Scientific Papers

The article analyzes the influence of chemical composition of hythane (a mixture of natural gas with hydrogen) on pressure in an engine combustion chamber. A review of the literature has showed the relevance of using hythane in transport energy industry, and also revealed a number of scientific papers devoted to studying the effect of hythane on environmental and traction-dynamic characteristics of the engine. We have studied a single-cylinder spark-ignited internal combustion engine. In the experiments, the varying factors are: engine speed (600 and 900 min-1), excess air ratio and hydrogen concentration in natural gas which are 29, 47 and 58% (volume).The article shows that at idling engine speed maximum pressure in combustion chamber depends on excess air ratio and proportion hydrogen in the air-fuel mixture – the poorer air-fuel mixture and greater addition of hydrogen is, the more intense pressure increases. The positive effect of hydrogen on pressure is explained by the fact that addition of hydrogen contributes to increase in heat of combustion fuel and rate propagation of the flame. As a result, during combustion, more heat is released, and the fuel itself burns in a smaller volume. Thus, the addition of hydrogen can ensure stable combustion of a lean air-fuel mixture without loss of engine power. Moreover, the article shows that, despite the change in engine speed, addition of hydrogen, excess air ratio, type of fuel (natural gas and gasoline), there is a power-law dependence of the maximum pressure in engine cylinder on combustion chamber volume. Processing and analysis of the results of the foreign and domestic researchers have showed that patterns we discovered are applicable to engines of different designs, operating at different speeds and using different hydrocarbon fuels. The results research presented allow us to reduce the time and material costs when creating new power plants using hythane and meeting modern requirements for power, economy and toxicity.

scholarly journals Effect of distal esophageal irritation on the changes of cystometry parameters to esophagus and colon distentions in rats

2019 ◽  
Vol 97 (8) ◽  
pp. 766-772
Author(s):  
Ezidin G. Kaddumi
Keyword(s):  
Electrical Stimulation ◽  
Urinary Bladder ◽  
Vagus Nerve ◽  
Storage Time ◽  
Distal Colon ◽  
Bladder Function ◽  
Maximum Pressure ◽  
Pressure Amplitude ◽  
Chemical Irritation ◽  
Stimulation Of

The coexistence of different visceral pathologies in patients suffering from irritable bowel syndrome, interstitial cystitis, and other pathologies, necessitates the study of these pathologies under complicated conditions. In the present study, cystometry recordings were used to investigate the effect of distal esophageal chemical irritation on the urinary bladder interaction with distal colon distention, distal esophageal distention, and electrical stimulation of abdominal branches of vagus nerve. Distal esophageal chemical irritation significantly decreased the intercontraction time via decreasing the voiding time. Also, distal esophageal chemical irritation significantly decreased the pressure amplitude by decreasing the maximum pressure. Following distal esophageal chemical irritation, distal esophageal distention was able to significantly decrease the intercontraction time by decreasing the storage time. However, 3 mL distal colon distention significantly increased the intercontraction time by increasing the storage time. On the other hand, following distal esophageal chemical irritation, electrical stimulation of abdominal branches of vagus nerve did not have any significant effect on intercontraction time. However, electrical stimulation of abdominal branches of vagus nerve significantly increased the pressure amplitude by increasing the maximum pressure. The results of this study demonstrate that urinary bladder function and interaction of bladder with other viscera can be affected by chemical irritation of distal esophagus.

The Study on Heating Running Schemes of Solar Energy Combined with Municipal Heating

2013 ◽  
Vol 790 ◽  
pp. 160-164
Author(s):  
Yong An Ao ◽  
Gang Li ◽  
Wei Xin Kong ◽  
Qi Feng
Keyword(s):  
Mathematical Model ◽  
Solar Energy ◽  
Water Temperature ◽  
Solar Collector ◽  
Heat Load ◽  
Environmental Benefits ◽  
Combination System ◽  
Save Energy ◽  
The Mathematical Model ◽  
Heat Amount

The research, based on combination system of solar energy and municipal heating network, studied the running scheme of combination system of solar energy and municipal heating network through ways of experiments and theoretical calculation of the mathematical model. Firstly, the research established mathematical model of heat equilibrium of the combination system of solar energy and municipal heating network; secondly, keeping the indoor heat load steady, compared the dynamic heat load provided by solar collector with that needed by heated room at the same time,determined time spans of the network stopping service and the heat load added by the network within 24 h. In the research we took a heating period in a typical room in Shenyang for example, under the conditions of low temperature floor radiant with heating index standard of 50W/ m2 and 50°C of the average supplied water temperature, 40 °C of the return water temperature, calculated and verified the established mathematical model. The results include: when the heat load provided by solar collector is greater or less than the heat needed by the room, how many heat amount should be supplied by the running network and the amount of water flow within the network pipes correspondingly, and how long the network runs or stops. The final conclusions include: whether the running scheme of the combination system can save energy? the conditions of energy saving in running a combination system, and whether the system can bring environmental benefits.

Simulation and Analysis on Operating Characteristics of Central Exhaust System in High-Rise Residential

2012 ◽  
Vol 614-615 ◽  
pp. 656-664 ◽  
Author(s):  
Gang Li ◽  
Yue Ren Wang ◽  
Guo Hui Feng ◽  
Ming Zhi Jiang ◽  
Qian Liu
Keyword(s):  
Cross Section ◽  
Exhaust System ◽  
Variable Cross Section ◽  
Maximum Pressure ◽  
Variable Cross ◽  
Main Duct ◽  
Operating Characteristics ◽  
Cross Section Area ◽  
Section Area ◽  
Operation Rate

Operating characteristics of variable cross section area of main duct in the main-branch central exhaust system was simulated based on various stories, operation rate and cross section area of main duct by FLUENT. The results show that there are certain obvious induced flow in the lower part of the system when the users in the upper floor work in the central exhaust system,and the internal pressure of main duct appears low- high-low trend in the system from the bottom to the top floor. The maximum pressure position is not in the bottom, but in the middle and lower floor of the system, where is the most disadvantageous floors of the exhaust system. It indicates that 400 mm x 500 mm is the necessary cross section area of main exhaust duct for 10 layers buildings,and 400 mm x 750 mm is the necessary one for 20 layers buildings.

Simulation and Experimental Study of a Porous Electroosmotic Pump

2011 ◽  
Vol 483 ◽  
pp. 320-326 ◽  
Author(s):  
Zhou Ling ◽  
Tao Yang ◽  
Fan Chao Meng ◽  
Lin Yi ◽  
Xiang Xian Zhang
Keyword(s):  
Porous Media ◽  
Flow Rate ◽  
Pore Diameter ◽  
Maximum Flow ◽  
Joule Heat ◽  
Maximum Pressure ◽  
Electrical Field ◽  
Electroosmotic Pump ◽  
The Mathematical Model ◽  
Truncated Gaussian

Aiming at the coupling problems of electrical field and flow field in porous media microchannels, the mathematical model of electroosmotic(EO) flow is built. For a single microchannel, the influence of voltage on velocity and joule heat is analyzed by using CoventorWare. Numerical analysis shows that the velocity is proportional to the voltage and the joule heat is small and negligible. For the porous media, the flow rate is investigated by truncated Gaussian distribution of pore diameter. The electroosmotic microporous pump is fabricated, and the experimental results indicate that the maximum flow rate of porous media micropump is 16.89ml/min and the maximum pressure is 120.1kPa.

Study on Knock Characteristics of Dimethyl Ether Fueled Homogenous Charge Compression Ignition-Direct Injection Combustion Engines

2015 ◽  
Vol 137 (6) ◽  
Author(s):  
Junxing Hou ◽  
Zhenhua Wen ◽  
Jianwei Liu ◽  
Zhiqiang Jiang
Keyword(s):  
Dimethyl Ether ◽  
Direct Injection ◽  
Correlation Coefficients ◽  
Maximum Pressure ◽  
Discrete Wavelet ◽  
Pressure Amplitude ◽  
Compression Ignition ◽  
Cylinder Pressure ◽  
Wavelet Energy ◽  
Four Levels

A two-cylinder diesel engine was modified for a dimethyl ether (DME) homogeneous charge compression ignition (HCCI)-direct injection (DI) engine. Knock characteristics are investigated based on in-cylinder pressure signals. The in-cylinder pressure is decomposed into four levels using discrete wavelet transform (DWT). The maximum pressure amplitudes and wavelet energy at four levels are approximately equal in normal combustion. With knock, both the maximum pressure amplitude and wavelet energy at the third level are the greatest. The correlation analysis shows that the correlation coefficients for maximum pressure amplitude and wavelet energy are quite valid for the second and third levels. It indicates that the correlation is stronger at frequencies which belong to resonant frequencies. The wavelet energy has slightly better performance than maximum pressure amplitude for identification of knock.

Self-generation of organized waves in an impinging turbulent jet at low Mach number

1982 ◽  
Vol 117 ◽  
pp. 425-441 ◽  
Author(s):  
Donald Rockwell ◽  
Andreas Schachenmann
Keyword(s):  
Mach Number ◽  
Phase Difference ◽  
Acoustic Waves ◽  
Near Field ◽  
Turbulent Jet ◽  
Maximum Pressure ◽  
Pressure Amplitude ◽  
Axisymmetric Cavity ◽  
Low Mach Number ◽  
Oscillation Frequencies

Self-generation of highly organized waves in a nominally turbulent jet at very low Mach number can arise from its impingement upon the downstream orifice of an axisymmetric cavity, having an impingement length much shorter than the corresponding acoustic wavelength. The oscillation frequencies are compatible with the resonant modes of a long pipe located upstream of the cavity and with jet-instability frequencies based on the column mode (0·3 [siml ] SD [siml ] 0·6), as well as the near-field shear layer mode (0·016 [siml ] Sθ0 [siml ] 0·03). Moreover, the frequency of the organized wave is constant from separation to impingement; consequently vortex pairing does not occur.Within the cavity, the pressure amplitude associated with the organized wave is directly related to the phase difference between the organized velocity fluctuations at separation and impingement. Maximum pressure amplitude occurs when this phase difference, measured along the cavity (i.e. jet) centre-line, is 2nπ. Streamwise amplitude and phase distributions of the organized wave cannot be explained from purely hydrodynamic considerations; however, they can be effectively modelled by superposing contributions from hydrodynamic and acoustic waves. This aspect has important consequences for externally excited jets as well.

Start-up and operating characteristics of a refrigerator operating on nitrogen-hydrocarbon mixtures with isothermal heat load

1994 ◽  
Vol 30 (7) ◽  
pp. 330-334
Author(s):  
S. P. Gorbachev ◽  
S. D. Ladokhin ◽  
V. D. Belous ◽  
Yu. N. Subbotin ◽  
Yu. V. Titov
Keyword(s):  
Heat Load ◽  
Operating Characteristics ◽  
Hydrocarbon Mixtures ◽  
Start Up

Pressure Pulsations in a Drum Excited by a Centrifugal Compressor Connected to a Piping System

2010 ◽  
Author(s):  
Itsuro Hayashi ◽  
Shigehiko Kaneko
Keyword(s):  
Resonant Frequency ◽  
Centrifugal Compressor ◽  
Three Dimensional ◽  
Calculation Model ◽  
Maximum Pressure ◽  
Piping System ◽  
Pressure Amplitude ◽  
Pressure Pulsations ◽  
Dynamic Absorber ◽  
Two Peaks

The characteristics of the pressure pulsations in a drum connected to a piping system excited by a centrifugal compressor or a blower operated at blade-passing frequencies were investigated. In this study, the equivalent resistance of a compressor and that of a piping system were introduced and linked to the three dimensional calculation model, so that the non-linear damping proportional to velocity squared in the system is properly incorporated. The experiment was performed in order to validate the proposed simulation model. As a result, the three dimensional pressure response in the drum as well as the pipe can be well evaluated by this model. Furthermore, the effect of the acoustic dynamic absorber on the pressure pulsations in the pipe and drum is evaluated. When the resonant frequency of the pipe coincides with that of the drum, two peaks appear in the frequency response curve around the resonant frequency of the pipe, because the drum acts as an acoustic dynamic absorber. It is shown that the maximum pressure amplitude in the drum is obtained when the resonant frequency of the pipe is slightly shifted from the resonant frequency of the drum under the small damping conditions. The effect of the damping in the drum and the mode shape of the drum on the maximum pressure amplitude in the drum is discussed in detail.

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