Initial Pressure Influence on Explosion Pressures of Methane-Air Deflagrations in Linked Vessels

2014 ◽  
Vol 936 ◽  
pp. 2130-2134
Author(s):  
Yi Hu Cui ◽  
Jun Cheng Jiang ◽  
Yuan Yu ◽  
Qing Wu Zhang
Keyword(s):  
Experimental Study ◽  
Linear Relationship ◽  
Peak Pressure ◽  
Pressure Rise ◽  
Initial Pressure ◽  
Pressure Variation ◽  
Peak Pressures ◽  
Vented Explosion ◽  
Pressure Evolution

An experimental study on pressure evolution during closed explosion and venting progress of methane–air mixtures ([CH4=10%]) in linked vessels was performed, for systems at various initial pressures (P0=0-0.08MPa). The effects of initial pressure on regularity of pressure variation in vessels were discussed. For the closed explosion in isolated vessel, the higher level of the initial pressure in isolated big vessel is, the larger the peak pressure and rate of pressure rise is, and the peak pressure increases nonlinearly with initial pressure; For closed explosion in linked vessels, the higher initial pressure within the linked vessels system leads to the higher peak pressures in two vessels and there is an approximate linear relationship between them, which is similar to explosion in isolated vessel. For vented explosion in linked vessels at higher initial pressure, venting has poorer effect on protection of the linked vessels.

PRESSURE VARIATION IN REAL ARTERIOVENOUS FISTULA: EXPERIMENTAL STUDY

2020 ◽  
Author(s):  
Jonhattan Ferreira Rangel ◽  
Willyam Brito de Almeida Santos ◽  
Kleiber Bessa ◽  
Thercio Costa
Keyword(s):  
Experimental Study ◽  
Arteriovenous Fistula ◽  
Pressure Variation

Combustion Characteristics of HCCI in Motorcycle Engine

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
Yuh-Yih Wu ◽  
Ching-Tzan Jang ◽  
Bo-Liang Chen
Keyword(s):  
Cylinder Head ◽  
Internal Combustion Engines ◽  
Peak Pressure ◽  
Pressure Rise ◽  
Combustion Characteristics ◽  
Hcci Combustion ◽  
Lower Maximum ◽  
Intake Air Heating ◽  
Gas Recirculation ◽  
Motorcycle Engine

Homogeneous charge compression ignition (HCCI) is recognized as an advanced combustion system for internal combustion engines that reduces fuel consumption and exhaust emissions. This work studied a 150 cc air-cooled, four-stroke motorcycle engine employing HCCI combustion. The compression ratio was increased from 10.5 to 12.4 by modifying the cylinder head. Kerosene fuel was used without intake air heating and operated at various excess air ratios (λ), engine speeds, and exhaust gas recirculation (EGR) rates. Combustion characteristics and emissions on the target engine were measured. It was found that keeping the cylinder head temperature at around 120–130°C is important for conducting a stable experiment. Two-stage ignition was observed from the heat release rate curve, which was calculated from cylinder pressure. Higher λ or EGR causes lower peak pressure, lower maximum rate of pressure rise (MRPR), and higher emission of CO. However, EGR is better than λ for decreasing the peak pressure and MRPR without deteriorating the engine output. Advancing the timing of peak pressure causes high peak pressure, and hence increases MRPR. The timing of peak pressure around 10–15 degree of crank angle after top dead center indicates a good appearance for low MRPR.

Application of the method of dimensional analysis in laser-shock-wave processing of titanium alloys with shape memory

2021 ◽  
pp. 66-72
Author(s):  
Keyword(s):  
Shock Wave ◽  
Finite Element ◽  
Plastic Zone ◽  
Shape Memory ◽  
Dimensional Analysis ◽  
Peak Pressure ◽  
Laser Shock ◽  
Zone Depth ◽  
Peak Pressures ◽  
Laser Shock Wave

The processes of laser-shock-wave processing of NiTi alloys with shape memory effect are investigated by the methods of dimensional analysis and finite element modeling. The dependences of the depth of the plastic zone on the peak pressure in the shock wave and the duration of the laser pulse are obtained at different peak pressures. Keywords: shape memory alloys, laser-shock-wave processing, dimensional analysis, residual stresses, plastic zone depth. [email protected]

scholarly journals Three-Dimensional Boundary Layer on a Compressor Rotor Blade at Peak Pressure Rise Coefficient

1986 ◽  
Author(s):  
B. Lakshminarayana ◽  
P. Popovski
Keyword(s):  
Boundary Layer ◽  
Rotor Blade ◽  
Peak Pressure ◽  
Pressure Coefficient ◽  
Three Dimensional ◽  
Pressure Rise ◽  
Layer Growth ◽  
Leakage Flow ◽  
Suction Surface ◽  
Compressor Rotor

A comprehensive study of the three-dimensional turbulent boundary layer on a compressor rotor blade at peak pressure rise coefficient is reported in this paper. The measurements were carried out at various chordwise and radial locations on a compressor rotor blade using a rotating miniature “V” configuration hot-wire probe. The data are compared with the measurement at the design condition. Substantial changes in the blade boundary layer characteristics are observed, especially in the outer sixteen percent of the blade span. The increased chordwise pressure gradient and the leakage flow at the peak pressure coefficient have a cumulative effect in increasing the boundary layer growth on the suction surface. The leakage flow has a beneficial effect on the pressure surface. The momentum and boundary layer thicknesses increase substantially from those at the design condition, especially near the outer radii of the suction surface.

The effects of increasing heel height on forefoot peak pressure

1999 ◽  
Vol 89 (2) ◽  
pp. 75-80 ◽  
Author(s):  
MG Mandato ◽  
E Nester
Keyword(s):  
Measurement System ◽  
Pressure Measurement ◽  
Peak Pressure ◽  
First Metatarsal ◽  
Heel Height ◽  
Peak Pressures ◽  
Pressure Measurement System

The purpose of this study was to determine the effect of increasing heel height on peak forefoot pressure. Thirty-five women were examined while wearing sneakers and shoes with 2-inch and 3-inch heels. An in-shoe pressure-measurement system was used to document the magnitude and location of plantar peak pressures. Pressure under the forefoot was found to increase significantly with increasing heel height. As the heel height increased, the peak pressure shifted toward the first metatarsal and the hallux. The reproducibility of data obtained with the in-shoe pressure-measurement system was tested in five subjects; the data were found to be reproducible to within approximately 3% of measured pressures.

Is TCC-EZ a Suitable Alternative to Gold Standard Total-Contact Casting?

2021 ◽  
Vol 111 (5) ◽  
Author(s):  
Umangi K. Bhatt ◽  
Hui Ying Foo ◽  
Mahalia P. McEvoy ◽  
Sarah J. Tomlinson ◽  
Cara Westphal ◽  
...  
Keyword(s):  
Gold Standard ◽  
Peak Pressure ◽  
Pressure Reduction ◽  
Reduced Pressure ◽  
Suitable Alternative ◽  
Total Contact Cast ◽  
Plantar Pressures ◽  
Signed Rank ◽  
Significant Difference ◽  
Peak Pressures

Background The total-contact cast (TCC) is the gold standard for off-loading diabetic foot ulcers (DFUs) given its nonremovable nature. However, this modality remains underused in clinical settings due to the time and experience required for appropriate application. The TCC-EZ is an alternative off-loading modality marketed as being nonremovable and having faster and easier application. This study aims to investigate the potential of the TCC-EZ to reduce foot plantar pressures. Methods Twelve healthy participants (six males, six females) were fitted with a removable cast walker, TCC, TCC-EZ, and TCC-EZ with accompanying brace removed. These off-loading modalities were tested against a control. Pedar-X technology measured peak plantar pressures in each condition. Statistical analysis of four regions of the foot (rearfoot, midfoot, forefoot, and hallux) was conducted with Friedman and Wilcoxon signed rank tests. Significance was set at P < .05. Results All of the off-loading conditions significantly reduced pressure compared with the control, except the TCC-EZ without the brace in the hallux region. There was no statistically significant difference between TCC-EZ and TCC peak pressure in any foot region. The TCC-EZ without the brace obtained significantly higher peak pressures than with the brace. The removable cast walker produced similar peak pressure reduction in the midfoot and forefoot but significantly higher peak pressures in the rearfoot and hallux. Conclusions The TCC-EZ is a viable alternative to the TCC. However, removal of the TCC-EZ brace results in minimal plantar pressure reduction, which might limit clinical applications of the TCC-EZ.

Numerical Simulations of Onset of Volute Stall Inside a Centrifugal Compressor

2008 ◽  
Author(s):  
Hua Chen ◽  
Strong Guo ◽  
Xiao-Cheng Zhu ◽  
Zhao-Hui Du ◽  
Stone Zhao
Keyword(s):  
Centrifugal Compressor ◽  
Peak Pressure ◽  
Stokes Equations ◽  
Pressure Ratio ◽  
Pressure Rise ◽  
Navier Stokes ◽  
Cross Sectional ◽  
Navier Stokes Equations ◽  
Mass Flow Rates ◽  
Discharge Section

In a previous publication (Guo & Chen et al., 2007), the authors solved the unsteady, 3-D Navier-Stokes equations with the k-ε turbulence model using CFX software to show that there is a volute stall coincided with the stage stall of a turbocharger centrifugal compressor operated at 423m/s tip speed and the stage stall frequency is dictated by a volute standing wave. This paper presents the flow condition at the vaneless diffuser and volute from the same simulation at various mass flow rates from stage peak efficiency to deep stage stall. Time averaged flow conditions show that (1) the influence of exducer blade passing at the volute inlet rapidly diminishes at the compressor peak pressure ratio point and the influence vanishes when the stage is in stall; (2) only at the peak pressure ratio point, circumferentially averaged, spanwise distribution of radial velocity at the volute inlet has an inflection point and the distribution meets the requirement of the Fjo̸rtoft instability theorem; (3) in the volute discharge section, the flow stalls after the stage stalls and the vortex core at the cross sectional center of the section breaks down; (4) impeller total pressure rise curve has a flat region in the middle before the stage stalls and (5) diffuser stall triggers the stage stall and drives the volute into stall.

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