UNSTEADY CAVITATION SIMULATION IN TRANSIENT PROCESS OF TURBINE FLOW METER

2010 ◽  
Vol 24 (13) ◽  
pp. 1503-1506 ◽  
Author(s):  
GANG CHEN ◽  
SHUHONG LIU ◽  
GUANGJUN CAO
Keyword(s):  
Source Terms ◽  
Governing Equations ◽  
Local Pressure ◽  
Flow Meter ◽  
Two Phase ◽  
Rotating Speed ◽  
Evaporation And Condensation ◽  
Liquid Products ◽  
The Given ◽  
Turbine Flow Meter

In a turbine flow meter, cavitation will take place when local pressure falls below the vapor pressure of liquid products and it usually speeds up the rotor at the given high flow rate. In order to study its effects on meter factor, numerical simulation on transient unsteady turbulent flow is carried out based on the mixture homogeneous two phase cavitation model which is deduced from the theory of evaporation and condensation on a plane. The momentum source terms from the variation rotating speed of transient processes and the cavitation mass transport source terms are introduced into the transient unsteady governing equations. The results show that the meter factor grows with the increase of the cavitation number and meter factor will be affected by cavitation.

A New Cavitation Model Based on Evaporation and Condensation Theory

2009 ◽  
Author(s):  
Gang Chen ◽  
Shuhong Liu ◽  
Guangjun Cao ◽  
Yulin Wu ◽  
Suhong Fu ◽  
...  
Keyword(s):  
Surface Tension ◽  
Aerodynamic Drag ◽  
Water Pressure ◽  
Bubble Diameter ◽  
Simulation Models ◽  
Cavitation Model ◽  
Local Pressure ◽  
Two Phase ◽  
Evaporation And Condensation ◽  
Model Based

Cavitation is a phenomenon which occurs where the local pressure falls off under the vapor pressure. Over the past few years, numerical simulation models for cavitation have been developed significantly in order to investigate the mechanism of cavitation. In the paper, A local homogeneous cavitation model based on the theory of evaporation and condensation has been deduced, which is used to describe the phase change between water and vapor. The RNG k–ε turbulence model is used to simulate the turbulent flow and the finite volume method is employed to discrete the governing equations. The effects of surface tension of water, pressure fluctuations and non-condensable gases are included in the mass transfer cavitation model. Also in order to neglect the effects of the quantities such as the bubble number and bubble diameter, which is difficult to measure, the relations between the aerodynamic drag and surface tension forces is used to describe the bubble diameter. In order to evaluate the new cavitation model, the two phase cavitation flows around a NACA0015 hydrofoil at different attack angle and different cavitation number are simulated by the new cavitation model, and compared with references, which showed good agreement with the experiments.

Heat Power Determination of Dv-290 Refrigerator’s Evaporator on the Basis of Thermodynamic Parameters of Inlet Air / Określenie Mocy Cieplnej Parownika Chłodziarki Dv-290 Na Podstawie Parametrów Termodynamicznych Powietrza Wlotowego

2012 ◽  
Vol 57 (4) ◽  
pp. 911-920
Author(s):  
Bernard Nowak ◽  
Zbigniew Kuczera
Keyword(s):  
Thermodynamic Parameters ◽  
Thermal Power ◽  
Correlation Coefficients ◽  
Specific Humidity ◽  
Physical Parameters ◽  
Air Cooling ◽  
Regression Equations ◽  
Evaporation And Condensation ◽  
Before And After ◽  
The Given

Abstract The present paper introduces a method for calculating the thermal power of DV-290 mining air cooler’s evaporator. The power usually differs from the nominal power given by the manufacturer. The thermodynamic parameters of cooled air are not obtained as a result of in situ measurements, but in indirect manner that is by determining the evaporation and condensation’s pressure values of R407C refrigerant. The pressure dependencies formulated as a function of air enthalpy at the evaporator’s inlet were obtained using calculations of a computer program which solves the system of equations describing heat and mass transfer in the refrigerator’s compressor on the basis of previous measurements of air performed before and after its cooling. The obtained dependencies are demonstrated in a graphical (fig. 2 and fig. 3) and analytical (the regression equations (19) and (20)) manner, the values of correlation coefficients are also presented. For the known evaporation and condensation pressure values of the refrigerant, and thus for its basic physical parameters the complete thermal power of the evaporator was determined, that is its: air cooling overt power, dehumidification occult power, temperature, relative humidity and specific humidity of air after its cooling. In addition, using the mentioned method, the capacity of DV-290 refrigerator’s evaporator is provided for the given thermodynamic parameters of air before cooling, along with air thermodynamic parameters after cooling.

Heat Transfer Analysis of Room-Temperature Finned-Tube Evaporator for Cryogenic Nitrogen

2011 ◽  
Vol 133 (9) ◽  
Author(s):  
Shun Ching Lee ◽  
Tzu-Min Chen
Keyword(s):  
Heat Flux ◽  
Room Temperature ◽  
Integrated Model ◽  
Finned Tube ◽  
Heat Transfer Analysis ◽  
Outlet Temperature ◽  
Ambient Conditions ◽  
Governing Equations ◽  
Initial Value ◽  
Two Phase

Abstract The behavior of cryogenic nitrogen in a room-temperature evaporator six meters long is analyzed. Trapezoid fins are employed to enhance the heat flux supplied by the environment. The steady-state governing equations specified by the mixed parameters are derived from the conservations of momentum and energy. The initial value problem is solved by space integration. The fixed ambient conditions are confirmed by way of the meltback effect. An integrated model is utilized to analyze the convective effect of two-phase flow, which dominates the evaporation behavior. Another integrated model is employed to determine the total heat flux from the environment to the wet surface of the evaporator. The foundation of the formation of an ice layer surrounding the evaporator is presented. If the fin height is shorter than 0.5 m, the whole evaporator is surrounded by ice layer. If the fin height is longer than 0.5 m, the total pressure drop of nitrogen in the tube is negligible. The outlet temperature is always within the range between −12 °C and 16 °C for the evaporator with the fin height of 1.0 m. For the evaporator with dry surface, the nitrogen has the outlet temperature less than the ambient temperature at least by 5 °C.

Analysis of a Turbine Flow Meter Calibration Curve using CFD

2015 ◽  
Author(s):  
Carl Tegtmeier ◽  
Phuriwat Anusonti-Inthra ◽  
James Winchester
Keyword(s):  
Calibration Curve ◽  
Flow Meter ◽  
Turbine Flow Meter

A New Cavitation-Induced-Momentum-Defect (CIMD) Correction Approach to Track Cavitation Events

2007 ◽  
Author(s):  
Vedanth Srinivasan ◽  
Abraham J. Salazar ◽  
Kozo Saito
Keyword(s):  
Liquid Phase ◽  
Transport Equation ◽  
Vapor Phase ◽  
Incompressible Flows ◽  
Vapor Transport ◽  
Source Terms ◽  
Local Pressure ◽  
Cloud Cavitation ◽  
Tracking Model ◽  
The Impact

A new unsteady cavitation event tracking model is developed for predicting vapor dynamics occurring in multi-dimensional incompressible flows. The procedure solves incompressible Navier-Stokes equations for the liquid phase with an additional vapor transport equation for the vapor phase. The model tracks regions of liquid vaporization and applies compressibility effects to compute the local variation in speed of sound using the Homogeneous Equilibrium Model (HEM) assumptions. The variation of local cell density as a function of local pressure is used to construct the source term in the vapor fraction transport equation. The novel Cavitation-Induced-Momentum-Defect (CIMD) correction methodology developed in this study serves to account for cavitation inception and collapse events as relevant momentum source terms in the liquid phase momentum equations. Effects of vapor phase accumulation and diffusion are incorporated by detailed relaxation models. A modified RNG K-ε model, including the effects of compressibility in the vapor regions, is employed for modeling turbulence effects. Turbulent kinetic energy and dissipation contributions from the vapor regions are integrated with the liquid phase turbulence using relevant source terms. Numerical simulations are carried out using a Finite Volume methodology available within the framework of commercial CFD software code Fluent v.6.2. Simulation results are in qualitative agreement with experiments for unsteady cloud cavitation behavior in planar nozzle flows. Multitude of mechanisms such as formation of vortex cavities, vapor cluster shedding and coalescence, cavity pinch off are sharply captured by the supplemented vapor transport equation. Our results concur with previously established theories concerning sheet and cloud cavitation such as the re-entrant jet motion, cavity closure and the impact of adverse pressure gradients on cavitation dynamics.

scholarly journals Polymerization of Isobutylene in a Rotating Packed Bed Reactor: Experimental and Modeling Studies

2021 ◽  
Vol 11 (21) ◽  
pp. 10194
Author(s):  
Wenhui Hou ◽  
Wei Wang ◽  
Yang Xiang ◽  
Yingjiao Li ◽  
Guangwen Chu ◽  
...  
Keyword(s):  
Strong Dependence ◽  
Average Molecular Weight ◽  
Packed Bed ◽  
Packed Bed Reactor ◽  
Mixing Efficiency ◽  
Polymerization Temperature ◽  
Analysis Method ◽  
Rotating Speed ◽  
Rotating Packed Bed ◽  
The Given

Polymerization of isobutylene (IB) for synthesizing highly reactive polyisobutylene (HRPIB) is characterized by a complicated fast intrinsic reaction rate; therefore, the features of its products exhibit a strong dependence on mixing efficiency. To provide uniform and efficient mixing, a rotating packed bed was employed as a reactor for polymerization of IB. The effects of operating parameters including polymerization temperature (T), rotating speed (N) and relative dosage of monomers and initiating systems ([M]0/[I]0) on number-average molecular weight (Mn) of HRPIB were studied. HRPIB with Mn of 2550 g·mol−1 and exo-olefin terminal content of 85 mol% were efficiently obtained at suitable conditions as T of 283 K, N of 1600 rpm and [M]0/[I]0 of 49. Moreover, the Mn can be regulated by changing T, N and [M]0/[I]0. Based on the presumptive-steady-state analysis method and the coalescence–redispersion model, a model for prediction of the Mn was developed and validated, and the calculated Mn values agreed well with experimental results, with a deviation of ±10%. The results demonstrate that RPB is a promising reactor for synthesizing HRPIB, and the given model for Mn can be applied for the design of RPB and process optimization.

scholarly journals Design, simulation and practical experimentation of miniaturized turbine flow sensor for flow meter assessment

2019 ◽  
Vol 8 (3) ◽  
pp. 777-788
Author(s):  
Salami Ifedapo Abdullahi ◽  
Mohamed Hadi Habaebi ◽  
Noreha Abd Malik
Keyword(s):  
Flow Simulation ◽  
Input Voltage ◽  
Flow Sensor ◽  
Data Logging ◽  
Sensors And Actuators ◽  
Flow Meter ◽  
Daily Lives ◽  
Automatic Data ◽  
3D Cad ◽  
Turbine Flow Meter

Flow sensors are very essential in many aspects of our daily lives. Many of the industrial processes need a very consistent flow sensor to monitor and check for irregularities in their system. Therefore, flow sensor is an important tool for advanced operation in industrial environment. In this paper, the design and development of a 3D fabricated flow sensor was carried out using SolidWork 3D CAD. SolidWork Flow Simulation was used to model the effect the turbine flow sensor would have on a constant flowing water while MATLAB Simulink flow graph was created to visualize the effect of turbine flow sensor response with voltage input. Afterwards, the design was 3D printed using UP Plus 2 3D printer. The experimentation involved selection of sensors, coding to control the turbine flow sensor and automatic data logging and storage. During the design phase, the sensors and actuators were assembled using locally sourced material. Subsequently, under controlled laboratory environment, the turbine flow sensor was tested using a DC motor which was programmed to control the revolution per minute(rpm) of the turbine flow sensor. The rpm and velocity of the turbine flow meter was measured and stored in a database via Microsoft Excel using Cool Term Software. A total number of 517 readings were analysed to evaluate the performance of the turbine flow sensor. The result shows that the turbine flow meter is responsive to the motor input voltage and yielded accurate measurement of rpm and velocity of turbine flow meter.

Determination of Pressure Profile During Closed-Vessel Test Through Computational Fluid Dynamics Simulation

2015 ◽  
Vol 8 (2) ◽  
Author(s):  
Ahmed Bougamra ◽  
Huilin Lu
Keyword(s):  
Solid Propellant ◽  
Time History ◽  
Initial Pressure ◽  
Pressure Profile ◽  
Dynamics Simulation ◽  
Solid Propellants ◽  
Closed Vessel ◽  
Governing Equations ◽  
Two Phase ◽  
Closed Chamber

Two-phase flow modeling of solid propellants has great potential for simulating and predicting the ballistic parameters in closed-vessel tests as well as in guns. This paper presents a numerical model describing the combustion of a solid propellant in a closed chamber and takes into account what happens in such two-phase, unsteady, reactive-flow systems. The governing equations were derived in the form of coupled, nonlinear axisymmetric partial differential equations. The governing equations with customized parameters were implemented into ansys fluent 14.5. The presented solutions predict the pressure profile inside the closed chamber. The results show that the present code adequately predicts the pressure–time history. The numerical results are in agreement with the experiment. Some discussions are given regarding the effect of the grain shape and the sensitivity of these predictions to the initial pressure of the solid propellant bed. The study demonstrated the capability of using the present model implemented into Fluent, to simulate the combustion of solid propellants in a closed vessel and, eventually, the interior ballistic process in guns.

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