scholarly journals Investigation of internal flow of Cryogenic injection

2020 ◽  
Vol 3 (2) ◽  
pp. 2
Author(s):  
Claus Franz Wehmann ◽  
Marcello Reis ◽  
Meng Lou ◽  
Oskar Josef Haidn
Keyword(s):  
Flow Rate ◽  
Strong Dependence ◽  
Internal Flow ◽  
Fluid Temperature ◽  
Two Phase ◽  
Long Time ◽  
Cryogenic Flow ◽  
Jet Injectors ◽  
Cryogenic Propellants

As part of an effort to understand the conditions for the ignition of cryogenic propellants in the low pressure environment, we conducted a research of internal flow of cryogenic jet. In this paper, the experimental investigation was exerted focusing on the qualitative morphology study of the cryogenic flow inside the jet injectors. The test facilities were carefully designed and allow for visualization and characterization of the flow. The results show a strong dependence of mass flow rate on the fluid temperature. The two-phase flow was observed even for a long time chilling down of the injector. The Jacob number is proved to be a good indicator for the flow regimes, and the bubbles are present in the flow every time. The injector geometry has an influence on the flow rate, with the tapered injector demonstrating a higher flow rate than the sharp one.

Damping of Tubes With Internal Two-Phase Flow

2006 ◽  
Author(s):  
Alexandre Gravelle ◽  
Annie Ross ◽  
Michel J. Pettigrew ◽  
Njuki W. Mureithi
Keyword(s):  
Flow Regime ◽  
Void Fraction ◽  
Two Phase Flow ◽  
Damping Ratio ◽  
Strong Dependence ◽  
Internal Flow ◽  
Piping System ◽  
Phase Flow ◽  
Two Phase ◽  
Phase Damping

Two-phase internal flow is present in many piping system components. Although two-phase damping is known to be a significant constituent of the total damping, the energy dissipation mechanisms that govern two-phase damping are not well understood. In this paper, damping of vertical clamped-clamped tubes subjected to two-phase air-water internal flow is investigated. Experimental data is reported, showing no dependence of two-phase damping on tube natural frequency, and a strong dependence on void fraction, flow velocity and flow regime. Two-phase damping increases with void fraction, reaches a maximum, and decreases beyond that point. The maximum damping ratio is roughly 3% for all flow velocities. It is reached at around 50% void fraction for high velocities, and 25% void fraction for low velocities. Data points plotted on two-phase flow pattern maps indicate that damping is greater in a bubbly flow regime than it is in a slug or churn regime. The maximum two-phase damping is reached at the highest void fraction before the transition to a slug or churn flow regime. It appears that two-phase damping may depend on the interface surface area between phases.

scholarly journals RELAP5 Analysis of OECD/NEA ROSA Project Experiment Simulating a PWR Loss-of-Feedwater Transient with High-Power Natural Circulation

2012 ◽  
Vol 2012 ◽  
pp. 1-15 ◽  
Author(s):  
Takeshi Takeda ◽  
Hideaki Asaka ◽  
Hideo Nakamura
Keyword(s):  
Flow Rate ◽  
High Power ◽  
Natural Circulation ◽  
Liquid Level ◽  
Injection System ◽  
Relief Valve ◽  
Two Phase ◽  
Fine Mesh ◽  
Post Test ◽  
Long Time

A ROSA/LSTF experiment was conducted for OECD/NEA ROSA Project simulating a PWR loss-of-feedwater (LOFW) transient with specific assumptions of failure of scram that may cause natural circulation with high core power and total failure of high pressure injection system. Auxiliary feedwater (AFW) was provided to well observe the long-term high-power natural circulation. The core power curve was obtained from a RELAP5 code analysis of PWR LOFW transient without scram. The primary and steam generator (SG) secondary-side pressures were maintained, respectively, at around 16 and 8 MPa by cycle opening of pressurizer (PZR) power-operated relief valve and SG relief valves for a long time. Large-amplitude level oscillation occurred in SG U-tubes for a long time in a form of slow fill and dump while the two-phase natural circulation flow rate gradually decreased with some oscillation. RELAP5 post-test analyses were performed to well understand the observed phenomena by employing a fine-mesh multiple parallel flow channel representation of SG U-tubes with a Wallis counter-current flow limiting correlation at the inlet of U-tubes. The code, however, has remaining problems in proper predictions of the oscillative primary loop flow rate and SG U-tube liquid level as well as PZR liquid level.

Two-Phase Flow Characterization of an Expandable Polystyrene Injector for Use in the Lost Foam Casting Process

2002 ◽  
Author(s):  
K. F. Wall ◽  
S. H. Bhavnani ◽  
R. A. Overfelt ◽  
D. S. Sheldon ◽  
K. Williams
Keyword(s):  
Flow Rate ◽  
Air Flow ◽  
Casting Process ◽  
Phase Flow ◽  
Air Flow Rate ◽  
Two Phase ◽  
Expandable Polystyrene ◽  
Foam Pattern ◽  
Lost Foam

A significant portion of casting defects in the Lost Foam Casting process can be traced back to a lack of consistency in the Expandable Polystyrene (EPS) foam pattern. The present study focuses on determining the cause of EPS foam pattern irregularities through the characterization of the two-phase flow of an EPS bead injector. The process variables studied during this experiment include fill time, fill pressure, EPS bead canister pressure, and fill hose diameter. It was found that the air flow rate under vented EPS bead canister condition using a 1.9 cm (3/4 inch) diameter fill hose increases 33% from a 276 kPa (40 psig) fill pressure to a 552 kPa (80 psig) fill pressure, and the EPS bead mass per cycle for a three second fill time increased 28% from a 276 kPa fill pressure to a 552 kPa fill pressure. The average EPS bead mass per cycle for a pressurized canister and a 1.9 cm diameter fill hose increased 71% from 55.22 grams for a 28 kPa EPS bead canister pressure to 80.21 grams for a 83 kPa EPS bead canister pressure at a fill pressure of 276 kPa. It was also discovered that the air flow rate under pressurized EPS bead canister condition is not a strong function of fill pressure but instead strongly depends on EPS bead canister pressure. The EPS bead mass per cycle for a 1.27 cm diameter fill hose exhibited a lower EPS bead mass per cycle than that for a 1.9 cm diameter fill hose for both the vented and pressurized canister conditions; however, the air flow rates and tip pressures observed for a 1.27 cm (1/2 inch) diameter fill hose showed similar behavior to those for a 1.9 cm diameter fill hose.

scholarly journals A Prediction Method of Wear for Volute Casing of a Centrifugal Slurry Pump

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Baocheng Shi ◽  
Jianpeng Pan ◽  
Lijuan Wu ◽  
Xingkai Zhang ◽  
Yijie Qiu ◽  
...  
Keyword(s):  
Centrifugal Pump ◽  
Prediction Method ◽  
Internal Flow ◽  
Two Phase ◽  
Systematic Analysis ◽  
Inlet Flow Rate ◽  
Long Time ◽  
Erosion Area ◽  
Solid Liquid ◽  
Erosion Intensity

Volute wall wear situations directly affect a long time safe operation for the centrifugal slurry pump unit and the whole system. In the present study, internal flow field is numerically investigated in a solid-liquid centrifugal pump, and the volute wall wear caused by the solid-liquid two-phase flow is predicted with wear equation. A systematic analysis on the wear mechanism of the centrifugal pump volute wall is carried out deeply, including the volute wall wear region, wear rate, and the relationship among inlet flow rate, particle concentration, and particle size. The predicted high erosion intensity area shows good agreement with the experimental erosion area, and the predicted and experimental areas are both located at the volute angle of 180° and near tongue. Therefore, the wear equation put forward in the present study is effective for estimating the erosion intensity and predicting the erosion area around the volute casing of a centrifugal pump.

scholarly journals Characterization of a Dual Chambered Two Phase Separator

2011 ◽  
Author(s):  
Casey Klein ◽  
Cable Kurwitz ◽  
Frederick Best
Keyword(s):  
Flow Rate ◽  
Gas Flow ◽  
Space Shuttle ◽  
Scaling Analysis ◽  
Gas Flow Rate ◽  
Two Phase ◽  
Space Applications ◽  
Higher Power ◽  
Phase Separator

Fuel cells have been used as a power source in the space shuttle for decades and are expected to be used in future higher power, larger systems. A new, passive gas/liquid phase separator for use in such large fuel cell space applications has been invented. It is a vortex separator designed to accommodate gas driven two phase flows. The work presented here is a first of a kind study of this newly invented separator examining the minimum inlet gas flow rate necessary for a stable vortex inside the separator as a function of separator size. A dimensional scaling analysis was done to predict this minimum inlet gas flow rate. Experiments were performed on the ground and in conjunction with the NASA microgravity simulating aircraft to validate modeling. The results of the experiments and scaling analysis are compared.

Research on Flow Instability in Vertical Narrow Annuli

2008 ◽  
Author(s):  
G. P. Wu
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Flow Instability ◽  
Heating Power ◽  
Fluid Temperature ◽  
Two Phase ◽  
System Pressure ◽  
Special Value ◽  
Narrow Annuli

A narrow annular test section of 1.5mm gap and 1800mm length was designed and manufactured, with good tightness and insulation. Experiments were carried out to investigate characteristics of flow instability of forced-convection in vertical narrow annuli. Using distilled water as work fluid, the experiments were conducted at pressures of 1.0∼3.0MPa, mass flow rates of 3.0∼25kg/h, heating power of 3.0∼ 6.5kW and inlet fluid temperature of 20 °C, 40 °C or 60°C. It was found that flow instability occured with fixed inlet condition and heating power when mass flow rate was below a special value. Effects of inlet subcooling, system pressure and mass flow rate on the system behavior were studied. The instability region is given, which has satisfactory agreement with results of the calculation based on the assumption of homogenous two-phase flow and thermodynamic equilibrium of the phases.

CBED analysis of impurity distributions in AlN

1990 ◽  
Vol 48 (4) ◽  
pp. 214-215
Author(s):  
Daniel Callahan ◽  
G. Thomas
Keyword(s):  
Aluminum Nitride ◽  
Bulk Material ◽  
Strong Dependence ◽  
Lattice Parameter ◽  
Promising Technique ◽  
Nitride Ceramics ◽  
Surface Phases ◽  
Convergent Beam ◽  
Oxygen Impurities

Oxygen impurities may significantly influence the properties of nitride ceramics with a strong dependence on the microstructural distribution of the impurity. For example, amorphous oxygen-rich grain boundary phases are well-known to cause high-temperature mechanical strength degradation in silicon nitride whereas solutionized oxygen is known to decrease the thermal conductivity of aluminum nitride. Microanalytical characterization of these impurities by spectral methods in the AEM is complicated by reactions which form oxygen-rich surface phases not representative of the bulk material. Furthermore, the impurity concentrations found in higher quality ceramics may be too low to measure by EDS or PEELS. Consequently an alternate method for the characterization of impurities in these ceramics has been investigated.Convergent beam electron diffraction (CBED) is a promising technique for the study of impurity distributions in aluminum nitride ceramics. Oxygen is known to enter into stoichiometric solutions with AIN with a consequent decrease in lattice parameter.

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