Computational Analysis of Cryogenic Flow Through a Control Valve

2003 ◽  
Author(s):  
Russell L. Daines ◽  
Jody L. Woods ◽  
Peter R. Sulyma
Keyword(s):  
Rocket Engine ◽  
Control Valve ◽  
Flow Coefficient ◽  
Computational Time ◽  
Working Fluid ◽  
Double Precision ◽  
Cryogenic Flow ◽  
Flow Through ◽  
Valve Modeling ◽  
Verification Process

The initial efforts to develop the capability to model valves used in rocket engine component testing at Stennis Space Center are documented. An axisymmetric model of a control valve with LN2 as the working fluid was developed. The goal was to predict the effect of change in the plug/seat region of the valve prior to testing. The valve flow coefficient was predicted for a range of plug positions. Verification of the calculations was carried out to quantify the uncertainty in the numerical answer. The modeled results compared well qualitatively to experimental trends. Additionally, insights into the flow processes in the valve were obtained. Benefits from the verification process included the ability to use coarser grids and insight into ways to reduce computational time by using double precision accuracy and non-integer grid ratios. Future valve modeling activities will include shape optimization of the valve/seat region and dynamic grid modeling.

Pressure Surge During Cryogenic Feedline Chilldown Process

2015 ◽  
Vol 8 (1) ◽  
Author(s):  
Gagan Agrawal ◽  
S. Sunil Kumar ◽  
Deepak Kumar Agarwal
Keyword(s):  
Numerical Study ◽  
Rocket Engine ◽  
Inlet Pressure ◽  
Working Fluid ◽  
Flash Evaporation ◽  
Two Phase ◽  
Numerical Studies ◽  
Start Up ◽  
Flow Through ◽  
Pressure Surge

Cryogenic fluid entering a warm feedline absorbs heat and undergoes rapid flash evaporation leading to pressure surges, which can retard the flow inside the feedline. It may have serious repercussion in operation of the rocket engine during start up. Experimental and numerical studies are carried out to examine the effect of inlet pressure and initial feedline temperature on pressure surges. An analytical model using sinda/fluint software is developed to investigate this complex two-phase flow phenomenon including the various boiling regimes that exist during line chilling. The numerical study is carried out considering 1D flow through a cryogenic feedline of 2.47 m long and 0.01 m inner diameter with liquid nitrogen at 77.3 K as working fluid. Predictions are made for the inlet pressure in the range of 0.28–0.76 MPa and initial wall temperature of 200 K and 300 K. Subsequently, an experimental test rig is setup and the model is validated with the experimental data. The studies show that within the range of parameter considered, the magnitude of pressure surge increases exponentially with increase in inlet pressure and decreases with the prechilling of feedline.

scholarly journals Periodic flow structures in a turbofan fan stage in windmilling

2020 ◽  
pp. 095441002094829
Author(s):  
Nicolás García Rosa ◽  
Adrien Thacker ◽  
Guillaume Dufour
Keyword(s):  
Mass Flow ◽  
Turbulence Intensity ◽  
Flow Separation ◽  
Variable Mass ◽  
Flow Coefficient ◽  
Test Bed ◽  
Ambient Conditions ◽  
Low Velocity ◽  
Blade Passing Frequency ◽  
Flow Through

In a fan stage under windmilling conditions, the stator operates under negative incidence, leading to flow separation, which may present an unsteady behaviour due to rotor/stator interactions. An experimental study of the unsteady flow through the fan stage of a bypass turbofan in windmilling is proposed, using hot-wire anemometry. Windmilling conditions are reproduced in a ground engine test bed by blowing a variable mass flow through a bypass turbofan in ambient conditions. Time-averaged profiles of flow coefficient are independent of the mass flow, demonstrating the similarity of velocity triangle. Turbulence intensity profiles reveal that the high levels of turbulence production due to local shear are also independent of the inlet flow. A spectral analysis confirms that the flow is dominated by the blade passing frequency, and that the separated regions downstream of the stator amplify the fluctuations locked to the BPF without adding any new frequency. Phase-locked averaging is used to capture the periodic wakes of the rotor blades at the rotor/stator interface. A spanwise behaviour typical of flows through windmilling fans is evidenced. Through the inner sections of the fan, rotor wakes are thin and weakly turbulent, and the turbulence level remains constant through the stage. The rotor wakes thicken and become more turbulent towards the fan tip, where flow separation occurs. Downstream of the stator, maximum levels of turbulence intensity are measured in the separated flow. Large periodical zones of low velocity and high turbulence intensity are observed in the outer parts of the separated stator wake, confirming the pulsating motion of the stator flow separation, locked at the blade passing frequency. Space-time diagrams show that the flow is chorochronic, and a 2 D non-linear harmonic simulation is able to capture the main interaction modes, however, the stator incidence distribution could be affected by 3 D effects.

Rack Level Modeling of Air Flow Through Perforated Tile in a Data Center

2012 ◽  
Author(s):  
Vaibhav K. Arghode ◽  
Pramod Kumar ◽  
Yogendra Joshi ◽  
Thomas S. Weiss ◽  
Gary Meyer
Keyword(s):  
Data Center ◽  
Body Force ◽  
Air Flow ◽  
The Body ◽  
Physical Models ◽  
Cfd Modeling ◽  
Computational Time ◽  
Force Model ◽  
Flow Through ◽  
Tile Surface

Effective air flow distribution through perforated tiles is required to efficiently cool servers in a raised floor data center. We present detailed computational fluid dynamics (CFD) modeling of air flow through a perforated tile and its entrance to the adjacent server rack. The realistic geometrical details of the perforated tile, as well as of the rack are included in the model. Generally models for air flow through perforated tiles specify a step pressure loss across the tile surface, or porous jump model based on the tile porosity. An improvement to this includes a momentum source specification above the tile to simulate the acceleration of the air flow through the pores, or body force model. In both of these models geometrical details of tile such as pore locations and shapes are not included. More details increase the grid size as well as the computational time. However, the grid refinement can be controlled to achieve balance between the accuracy and computational time. We compared the results from CFD using geometrical resolution with the porous jump and body force model solution as well as with the measured flow field using Particle Image Velocimetry (PIV) experiments. We observe that including tile geometrical details gives better results as compared to elimination of tile geometrical details and specifying physical models across and above the tile surface. A modification to the body force model is also suggested and improved results were achieved.

scholarly journals Surrogate Models Applied to Optimized Organic Rankine Cycles

Energies ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 8456
Author(s):  
Icaro Figueiredo Vilasboas ◽  
Victor Gabriel Sousa Fagundes dos Santos ◽  
Armando Sá Ribeiro Júnior ◽  
Julio Augusto Mendes da Silva
Keyword(s):  
Polynomial Regression ◽  
Surrogate Models ◽  
Industrial Plant ◽  
Computational Time ◽  
Working Fluid ◽  
Or Efficiency ◽  
Specific Cost ◽  
Complex Models ◽  
Organic Rankine Cycles ◽  
Main Components

Global optimization of industrial plant configurations using organic Rankine cycles (ORC) to recover heat is becoming attractive nowadays. This kind of optimization requires structural and parametric decisions to be made; the number of variables is usually high, and some of them generate disruptive responses. Surrogate models can be developed to replace the main components of the complex models reducing the computational requirements. This paper aims to create, evaluate, and compare surrogates built to replace a complex thermodynamic-economic code used to indicate the specific cost (US$/kWe) and efficiency of optimized ORCs. The ORCs are optimized under different heat sources conditions in respect to their operational state, configuration, working fluid and thermal fluid, aiming at a minimal specific cost. The costs of 1449.05, 1045.24, and 638.80 US$/kWe and energy efficiencies of 11.1%, 10.9%, and 10.4% were found for 100, 1000, and 50,000 kWt of heat transfer rate at average temperature of 345 °C. The R-square varied from 0.96 to 0.99 while the number of results with error lower than 5% varied from 88% to 75% depending on the surrogate model (random forest or polynomial regression) and output (specific cost or efficiency). The computational time was reduced in more than 99.9% for all surrogates indicated.

scholarly journals Design and Fabrication of Two Step Speed Control of a Cylinder Circuit using Pneumatics

2019 ◽  
Vol 8 (6S2) ◽  
pp. 512-516
Keyword(s):  
Flow Control ◽  
High Speed ◽  
Air Flow ◽  
Control Valve ◽  
Speed Control ◽  
Flow Control Valve ◽  
Push Button ◽  
Low Speed ◽  
Flow Through

The main aim of our project is to design and fabrication of pneumatic two step speed control of a cylinder. Initially the flow from the FRL retracts the cylinder when the push button is in its spring offset position. When it is pushed the flow pilots actuate. The air passes through the flow control and shuttle valve. Then the cylinder extends with high speed as the valve allows more air to enter the cylinder. When the piston reaches the position it operates the cam push button and pilot air flow through this and actuate 5/2 pilot operated valve and reaches flow control valve which permits less air. Then the flow through enters the shuttle valve to cylinder and allows the cylinder to extend at relatively low speed. At the end of extension stroke deactivating push button retracts the cylinder. Thus the speed of cylinder is controlled and project can be achieved

scholarly journals HERMETIZATION OF VALVE SEALS FOR CRYOGENIC FLUIDS

2020 ◽  
Vol 6 (2) ◽  
pp. 12-19
Author(s):  
Yuri I. Kondrashov ◽  
Elena N. Ermilova ◽  
Anna N. Vidyaskina
Keyword(s):  
Mechanical Properties ◽  
Contact Pressure ◽  
Phase State ◽  
Working Fluid ◽  
Cryogenic Temperatures ◽  
Two Phase ◽  
Plastic Properties ◽  
Cryogenic Fluids ◽  
Specific Contact ◽  
Flow Through

For units providing flow control for cryogenic fluids and operating under conditions of a significant change in the temperature range from positive to cryogenic and in a two-phase state of the working fluid, the problem of sealing the closure members of the units (valve pairs) becomes urgent.Joint sealing is ensured by creating contact pressure in the joint through deforming the roughness peaks obtained by surface treatment of the valve pair.The mechanical properties of the materials of the contacting valve pairs change significantly under the influence of cryogenic temperatures. First of all, the plastic properties are reduced, therefore, the creation of increased contact pressure is required.The article presents a methodology for evaluation of changes in the microgeometry of contacting surfaces depending on the specific contact pressure. It also allows one to evaluate the conductivity of microgaps in the viscous and molecular regimes of fluid flow through contacting surfaces.

Radial Impeller Forces Using CFD: Part II — A Comparison Between Compressible and Incompressible Flows

2002 ◽  
Author(s):  
Daniel O. Baun ◽  
Ronald D. Flack
Keyword(s):  
Mach Number ◽  
Flow Rate ◽  
Incompressible Flows ◽  
Lateral Force ◽  
Magnetic Bearing ◽  
Flow Coefficient ◽  
Low Flow ◽  
Working Fluid ◽  
Centrifugal Impeller ◽  
Cfd Model

Lateral centrifugal impeller forces are calculated using the CFD model developed in Part I of this paper. The impeller forces are evaluated by integrating the pressure and momentum profiles at both the impeller inlet and exit planes. Direct impeller lateral force measurements were made using a magnetic bearing supported pump rotor. Comparisons between the simulated and measured forces are first made for both average and transient impeller forces with water as the working fluid. Air was then substituted as the working fluid in the validated CFD model and the effect of impeller Mach number and Reynolds number on the static impeller lateral forces was investigated. The non-dimensional lateral impeller force characteristics as a function of normalized flow coefficient are similar in character between the incompressible and compressible case. At the matching point flow coefficient the non-dimensional impeller force magnitude was the same for all compressible and incompressible simulations. For any normalized flow rate other than the matching point flow rate, the magnitude of the non-dimensional impeller force increased as the Mach number increased. As the choke condition was approached the magnitude of the impeller force increased exponentially. As the Mach number increased the transition of the force orientation vector from the low flow asymptote to the high flow asymptote occurred over a progressively smaller range of flows.

Flow swirl impact at the rocket engine nozzle inlet on the flow coefficient

2021 ◽  
Vol 28 (2) ◽  
pp. 142-151
Author(s):  
Ruslan Shaidullin ◽  
Albert Bekerov ◽  
Andrey Sabirzyanov
Keyword(s):  
Rocket Engine ◽  
Flow Coefficient ◽  
Flow Swirl ◽  
Nozzle Inlet

Use of CFD to Improve Control Valve Effectiveness

2019 ◽  
Author(s):  
Alton Reich
Keyword(s):  
Flow Control ◽  
Control Valve ◽  
Steam Pressure ◽  
Steam Flow ◽  
Effective Control ◽  
Flow Control Valve ◽  
Flow Rates ◽  
Wide Range ◽  
Flow Through ◽  
Inlet Conditions

Abstract Control valves are used to adjust fluid flow rates in an extremely wide variety of applications. This paper discusses a steam flow control valve that is required to operate with a fairly wide range of inlet conditions (steam pressure) and provide effective control over a fairly wide range of steam flow rates. In this particular case a valve design was developed using “classical” methods — a combination of experience and hand calculations. The valve was tested and it did not provide adequate control over the flow for the application. The valve redesign effort used CFD to gain insight into the flow through the valve in order to evaluate control performance before the valve was fabricated and assembled. Several internal geometries were assessed and compared in order to identify two configurations that would meet the flow control requirements. These configurations were fabricated and tested and deemed to be adequate.

Sign in / Sign up

Export Citation Format

Share Document