scholarly journals CALCULATION OF DEPARTURE FROM NUCLEATE BOILING CONDITIONS FOR THE SPERT III REACTOR IN THE HIGH PRESSURE REGION

1962 ◽  
Author(s):  
J Dugone
Keyword(s):  
High Pressure ◽  
Nucleate Boiling ◽  
Pressure Region ◽  
High Pressure Region

PVB Blast Load Enhancement due to Mach Stem

2019 ◽  
Author(s):  
Will Lowry ◽  
Jihui Geng
Keyword(s):  
High Pressure ◽  
Blast Wave ◽  
Triple Point ◽  
Petroleum Refining ◽  
Ground Level ◽  
Chemical Processing ◽  
Mach Stem ◽  
Blast Pressure ◽  
Pressure Region ◽  
High Pressure Region

Abstract A pressure vessel burst (PVB) is an explosion scenario commonly encountered at chemical processing and petroleum refining facilities. Existing methodologies are available to predict the blast loads resulting from a spherical or cylindrical PVB source, with the PVB source either at grade or at an elevation. In the case of an elevated PVB source, the resulting blast wave will reflect from the ground at an angle. This ground level reflection will result in the formation of a Mach stem at certain angles between the incident blast wave and ground, with the required angles dependent on the blast wave overpressure. The triple point associated with the Mach stem moves upwards as the Mach stem progresses forwards, which can create a region of high blast pressure. This paper focuses on the investigation of a methodology that can be used to determine the high-pressure region generated by the Mach stem, along with the associated blast pressure, as a function of the PVB source elevation and incident blast pressure.

On Three-Dimensional Flat-Top Defects Passing Through an EHL Point Contact: A Comparison of Modeling with Experiments

2005 ◽  
Vol 127 (1) ◽  
pp. 51-60 ◽  
Author(s):  
A. Fe´lix-Quin˜onez ◽  
P. Ehret ◽  
J. L. Summers
Keyword(s):  
High Pressure ◽  
Film Thickness ◽  
Three Dimensional ◽  
Point Contact ◽  
Numerical Results ◽  
Shaped Surface ◽  
Pure Rolling ◽  
Pressure Region ◽  
Inlet Zone ◽  
High Pressure Region

A direct comparison between experimental and numerical results for the passage of an array of 3D flat-top, square shaped surface features through an EHL point contact is presented. Results for pure rolling conditions show that the features’ deformation in the high-pressure region is governed by their ability to entrap lubricant both underneath and in the grooves during their passage through the inlet zone. Film perturbations associated with each defect occur as locally enhanced regions of lubricant and film thickness micro-constrictions. Under sliding conditions the features sustain further deformations as they traverse the high-pressure conjunction and meet the highly viscous lubricant entrapped in the grooves, which moves at a different velocity. Lubricant is also seen to accumulate just in front or behind the features depending on the slide-to-roll ratio. Overall, the results highlight the importance of understanding the effects of the defects structure and the lubricant rheology on the film thickness to unravel the effects of real roughness patterns.

Pyrolysis of Trifluoroacetaldehyde

1973 ◽  
Vol 51 (14) ◽  
pp. 2292-2296 ◽  
Author(s):  
Michael T. H. Liu ◽  
Leon F. Loucks ◽  
Robert C. Michaelson
Keyword(s):  
Thermal Decomposition ◽  
High Pressure ◽  
Free Radicals ◽  
Rate Equation ◽  
Pressure Dependence ◽  
Inert Gas ◽  
Order Process ◽  
First Order ◽  
Pressure Region ◽  
High Pressure Region

The thermal decomposition of trifluoroacetaldehyde has been studied over the 460–520 °C temperature range, and at pressures from 4 to 400 mm Hg. The experimental rate equation in the high-pressure region is of the form: Rate = k[CF3CHO]3/2 where[Formula: see text]The results are consistent with a mechanism initiated by a first order process and terminated by a second order recombination of two CF3 free radicals. At lower pressures (40 mm Hg), the ratio of kinit/kterm is pressure dependent and the overall order increases. The effects of added inert gas confirm this pressure dependence.

scholarly journals Sensitivity Analysis of Tunable Equation of State Material Model In Pulsed Mercury Target Simulation

2021 ◽  
Author(s):  
Lianshan Lin ◽  
Drew Winder
Keyword(s):  
High Pressure ◽  
Equation Of State ◽  
Material Model ◽  
High Energy ◽  
Model Parameters ◽  
Strain Response ◽  
Target Structure ◽  
Stationary Target ◽  
Pressure Region ◽  
High Pressure Region

Abstract A pulsed neutron spallation target is subjected to very short but intense loads from repeated proton pulses. Approximately 60% of the energy from each proton pulse is deposited into the mercury target material and the stainless-steel target structure, leading to a high-pressure region in both the stationary target structure and the flowing mercury. The high-pressure region propagates and leads to fluid-structure interaction. The resultant loading on the target structure containing liquid mercury is difficult to predict, although various simulation approaches and material models for the mercury have been tried. To date, the best match of simulation to experimental data is obtained by using an equation of state (EOS) material model with a specified tensile cutoff pressure, which simulates the cavitation threshold. The inclusion of a threshold to represent cavitation is key to the successful predictions of stress waves triggered by the high-energy pulse striking the mercury and vessel. However, recent measurements of target structure strain show that significant discrepancies remain between the measured and simulated strain values in the EOS mercury model. These differences grow when noncondensable helium gas is intentionally injected into the flowing mercury to reduce the loading on the structure. An EOS-based proportional–integral–derivative (PID) mercury model has been proposed to reduce the gap between the measured and simulated vessel strain responses for targets with gas injection. The conceptual and numerical description and initial investigation of the PID model are presented in previous work. Further studies of this PID model — including the sensitivity of the structure’s strain response to model parameters (the tensile cutoff, PID parameters Kp, Ki, and Kd) — are reported in this article. Results show the strain response is more sensitive to changes in the tensile cutoff value than to changes in the model parameters Kp, Ki, and Kd. These results will aid in future work where the model parameters will be optimized to match simulation data to strain measurements.

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