BIOFLUID FLOW THROUGH A THROTTLE VALVE: A COMPUTATIONAL FLUID DYNAMICS STUDY OF CAVITATION

2016 ◽  
Vol 16 (03) ◽  
pp. 1650034 ◽  
Author(s):  
XIUMEI LIU ◽  
JIE HE ◽  
JIYUN ZHAO ◽  
ZHENG LONG ◽  
WENHUA LI ◽  
...  
Keyword(s):  
Pressure Drop ◽  
High Speed ◽  
High Viscosity ◽  
Initial Position ◽  
Operating Conditions ◽  
Valve Seat ◽  
Cavitation Phenomenon ◽  
Throttle Valve ◽  
Valve Opening ◽  
Flow Through

Biofluid flow through a throttle valve is investigated numerically and experimentally in our paper. Numerical studies are performed in order to obtain the mass flow rate through the valve under different operating conditions. Pressure drop behind the throttle valve and formation of the vortex flow downstream has been evaluated. The vortices were mainly distributed on top of the valve rod, the corner of the channel and the corner of the valve seat. When valve opening increases, the vortices grow and cause higher pressure drop. In other words, more energy is lost due to these growing vortices and high viscosity of biofluid. Furthermore, experimental flow visualization is conducted to capture cavitation images near the orifice using high-speed camera. The initial position of cavitation occurred near throttle orifice while cavitation zone downstream is caused by circulating bubbles clusters. As the opening of the valve is decreased, the area and strength of vortices in the corner of the channel grow and cause higher pressure drop firstly, then decrease. In addition, there are a lot of bubble clusters on top of the valve rod and the corner of the valve seat, which flowed downstream and collapsed, then filled the entire channel. In general, the valve opening plays very important role in the performance of a throttle valve. The results would help to observe, understand and manage the cavitation phenomenon in a throttle valve, and improve the performance of throttle valves.

scholarly journals Investigation of flow characteristics in the U-shaped throttle valve

2019 ◽  
Vol 11 (3) ◽  
pp. 168781401983049 ◽  
Author(s):  
Jie He ◽  
Beibei Li ◽  
Xiumei Liu
Keyword(s):  
High Speed ◽  
Fluid Model ◽  
Flow Characteristics ◽  
Back Pressure ◽  
Cavitation Flow ◽  
Pressure Drops ◽  
Cavitation Phenomenon ◽  
Throttle Valve ◽  
Valve Opening ◽  
And Performance

Experimental and numerical analysis of cavitation flow in the U-shaped throttle valve is presented in this article. Cavitation flow has been analyzed numerically using the volume of fluid model while the pictures are captured by a high-speed camera. The results reveal that the distribution of pressure is extremely inhomogeneous, and the pressure drop zone is mainly distributed in the narrow U-shaped groove. Cavitation bubble occurs around the orifice and develops continuously since the pressure drops. The nascent, developed, and collapsed zone of the cavitation within U-shaped throttle valve are also presented. In addition, a high-speed jet flow is formed when the oil flows out the U-shaped orifice, a vortex appears and cavitation bubbles appear. Then, cavitation evolution and the effect of back pressure and the valve opening on cavitation behavior have been discussed. Increasing back pressure will weaken the cavitation intensity and suppress the cavitation effectively. The valve opening also affects the cavitation flow and performance of the U-shaped throttle valve. With the increase of valve opening, cavitation area first increases and then decreases. The results and conclusions presented in this article give the basis for better understanding the cavitation phenomenon in a throttle valve.

The Calculation Method and Experimental Research on Throttling Pressure Drop during Kill a Well

2012 ◽  
Vol 229-231 ◽  
pp. 495-498
Author(s):  
Hui Xin Liu ◽  
Xian Min Yang ◽  
Cheng Tao Li ◽  
Xiang Cheng
Keyword(s):  
Pressure Drop ◽  
Calculation Method ◽  
Engineering Practice ◽  
Exploration Process ◽  
Throttle Valve ◽  
Long Time ◽  
Valve Opening ◽  
Casing Pressure ◽  
The Relationship ◽  
Control Accuracy

There is a common problem during kill a well, which is how to quickly and accurately control the surface casing pressure according to the requirements for killing a well. A step-by-step exploration process is employed on operation sites. Continuously adjusting throttle valve to acquire surface casing pressure may lead to failure of kill operation because of its long time and low control accuracy. Obviously, if the calculation problems of throttling drawdown can be resolved,the relationship between drawdown and throttle valve opening can be found and the course of explorating can be converted into a straight course.Then the success rate of killing well can be improved. More importantly, this can make automatic controll of surface casing pressure possible. The paper built the calculation method of throttling pressure drop by theoretical analysis and verified the calculation method by adopting it into field test. The result has showed that the calculation method of throttling pressure drop coincides with experimental results and it can be used in engineering practice.

Turbulent Transition and Pressure Drop in Solid-High Viscosity Liquid Upward Flow through Vertical Pipe-

2004 ◽  
Vol 30 (4) ◽  
pp. 509-514 ◽  
Author(s):  
Hideki TOKANAI ◽  
Eiji HARADA ◽  
Jun-ichi HASEGAWA ◽  
Masafumi KURIYAMA
Keyword(s):  
Pressure Drop ◽  
High Viscosity ◽  
Upward Flow ◽  
Vertical Pipe ◽  
Turbulent Transition ◽  
Flow Through

High Speed Flow through Perforated Plates

1960 ◽  
Vol 64 (590) ◽  
pp. 103-105
Author(s):  
P. G. Morgan
Keyword(s):  
Pressure Drop ◽  
High Speed ◽  
Perforated Plate ◽  
Wire Mesh ◽  
Flow Conditions ◽  
High Speed Flow ◽  
Perforated Plates ◽  
Speed Flow ◽  
Flow Through ◽  
Points Of View

The flow through porous screens has been widely studied from both the theoretical and experimental points of view. The most widely used types of screen are the wire mesh and the perforated plate, and the majority of the literature has been concerned with the former. Several attempts have been made to correlate the parameters governing the flow through such screens, i.e. the pressure drop, the flow conditions and the geometry of the mesh.

High Speed Flow Through Wire Gauzes

1959 ◽  
Vol 63 (584) ◽  
pp. 474-475 ◽  
Author(s):  
P. G. Morgan
Keyword(s):  
Pressure Drop ◽  
Pressure Loss ◽  
High Speed ◽  
Static Pressure ◽  
Flow Conditions ◽  
High Speed Flow ◽  
Speed Flow ◽  
Wire Gauze ◽  
Flow Through

The Flow of Fluids through screens has been widely studied with particular importance being attached to the measurement of the pressure drop caused by a screen and its relation to the screen geometry and the flow conditions. The majority of the investigations have been carried out on wire gauze screens mounted in ducts with air passing through them, the static pressure being measured on either side of the gauze. Attempts have been made by Weighardt Annand and Grootenhuisto correlate the gauze geometry with the pressure drop and to enable the pressure loss over a given screen and with given flow conditions to be predicted.

Experimental Investigation Into the High Altitude Relight of a Three-Cup Combustor Sector

2018 ◽  
Author(s):  
Michael J. Denton ◽  
Samir B. Tambe ◽  
San-Mou Jeng
Keyword(s):  
Pressure Drop ◽  
High Altitude ◽  
High Speed ◽  
Development Process ◽  
Recirculation Zone ◽  
Operating Conditions ◽  
Pressure Drops ◽  
High Speed Video ◽  
Air Jet ◽  
Flame Development

The altitude relight of a gas turbine combustor is an FAA and EASA regulation which dictates the successful re-ignition of an engine and its proper spool-up after an in-flight shutdown. Combustor pressure loss, ambient pressure, ambient temperature, and equivalence ratio were all studied on a full-scale, 3-cup, single-annular aviation combustor sector to create an ignition map. The flame development process was studied through the implementation of high-speed video. Testing was conducted by placing the sector horizontally upstream of an air jet ejector in a high altitude relight testing facility. Air was maintained at room temperature for varying pressure, and then the cryogenic heat exchanger was fed with liquid nitrogen to chill the air down to a limit of −50 deg F, corresponding with an altitude of 30,000 feet. Fuel was injected at constant equivalence ratios across multiple operating conditions, giving insight into the ignition map of the combustor sector. Results of testing indicated difficulty in achieving ignition at high altitudes for pressure drops greater than 2%, while low pressure drops show adequate performance. Introducing low temperatures to simulate the ambient conditions yielded a worse outcome, with all conditions having poor results except for 1%. High-speed video of the flame development process during the relight conditions across all altitudes yielded a substantial effect of the pressure drop on ignitability of the combustor. An increase in pressure drop was associated with a decrease in the likelihood of ignition success, especially at increasing altitudes. The introduction of the reduced temperature effect exacerbated this effect, further hurting ignition. High velocity regions in the combustor were detrimental to the ignition, and high area, low velocity regions aided greatly. The flame tended to settle into the corner recirculation zone and recirculate back into the center-toroidal recirculation zone (CTRZ), spreading downstream and likewise into adjacent swirl cups. These tests demonstrate the need for new combustor designs to consider adding large recirculation zones for combustor flame stability that will aid in relight requirements.

Visualization of Supercritical Carbon Dioxide Flow Through a Converging-Diverging Nozzle

2019 ◽  
Author(s):  
Chang Hyeon Lim ◽  
Gokul Pathikonda ◽  
Sandeep Pidaparti ◽  
Devesh Ranjan
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Critical Point ◽  
High Speed ◽  
Operating Conditions ◽  
Higher Plant ◽  
Two Phase ◽  
Pressure Profiles ◽  
Flow Through ◽  
Supercritical Carbon

Abstract Supercritical carbon dioxide (sCO2) power cycles have the potential to offer a higher plant efficiency than the traditional Rankine superheated/supercritical steam cycle or Helium Brayton cycles. The most attractive characteristic of sCO2 is that the fluid density is high near the critical point, allowing compressors to consume less power than conventional gas Brayton cycles and maintain a smaller turbomachinery size. Despite these advantages, there still exist unsolved challenges in design and operation of sCO2 compressors near the critical point. Drastic changes in fluid properties near the critical point and the high compressibility of the fluid pose several challenges. Operating a sCO2 compressor near the critical point has potential to produce two phase flow, which can be detrimental to turbomachinery performance. To mimic the expanding regions of compressor blades, flow through a converging-diverging nozzle is investigated. Pressure profiles along the nozzle are recorded and presented for operating conditions near the critical point. Using high speed shadowgraph images, onset and growth of condensation is captured along the nozzle. Pressure profiles were calculated using a one-dimensional homogeneous equilibrium model and compared with experimental data.

An Experimental Study on Opening Delay of a Reed Valve for Reciprocating Compressors

2011 ◽  
Author(s):  
Fumitaka Yoshizumi ◽  
Yasuhiro Kondoh ◽  
Kazunori Yoshida ◽  
Takahiro Moroi ◽  
Masakazu Obayashi ◽  
...  
Keyword(s):  
High Speed ◽  
Gas Flow ◽  
Valve Seat ◽  
Film Rupture ◽  
Air Conditioners ◽  
Oil Film ◽  
Gas Compression ◽  
Valve Opening ◽  
Reed Valve ◽  
Opening Process

Automatic reed valves are widely used to control refrigerant gas flow in reciprocating compressors for automotive air conditioners. The oil film in the clearance between the reed and the valve seat causes a delay in opening of the valve. This opening delay of the discharge valve leads to over compression, which increases losses such as friction in sliding components and gas overheating. Therefore it is important to understand the behavior both of the oil film and the elastic reed deformation in order to reduce losses due to the delay. This study aims to develop an experimental setup that enables simultaneous visualization of the oil film rupture and measurement of the reed deformation, and to observe this behavior during the valve opening process. The gas-compression stroke is simulated by controlling compressed air with an electromagnetic valve. The oil film rupture is visually observed using a high speed camera through a special valve seat made of glass. The total deformation of the cantilever reed is identified by multipoint strain measurement with 12 strain gauges. The experiment finds that the opening process is divided into four stages. In the first stage, the reed remains stuck to the seat and deforms while the bore pressure increases. In the second stage, cavitation occurs in the oil film and the film starts to rupture. In the third stage, the oil film ruptures and the bore pressure starts to decrease. Finally, in the fourth stage, the reed is separated from the seat and the gas flows through the valve. Reducing the reed/seat contact area changes the reed deformation in the first stage, thereby increasing the reed/seat distance and realizing an earlier oil film rupture and a shorter delay.

Single-Phase and Two-Phase Flow Through Thin and Thick Orifices in Horizontal Pipes

2012 ◽  
Vol 134 (9) ◽  
Author(s):  
Manmatha K. Roul ◽  
Sukanta K. Dash
Keyword(s):  
Pressure Drop ◽  
Single Phase ◽  
Two Phase Flow ◽  
Operating Conditions ◽  
Orifice Diameter ◽  
Phase Flow ◽  
Two Phase ◽  
Pressure Drops ◽  
Horizontal Pipes ◽  
Flow Through

Two-phase flow pressure drops through thin and thick orifices have been numerically investigated with air–water flows in horizontal pipes. Two-phase computational fluid dynamics (CFD) calculations, using the Eulerian–Eulerian model have been employed to calculate the pressure drop through orifices. The operating conditions cover the gas and liquid superficial velocity ranges Vsg = 0.3–4 m/s and Vsl = 0.6–2 m/s, respectively. The local pressure drops have been obtained by means of extrapolation from the computed upstream and downstream linearized pressure profiles to the orifice section. Simulations for the single-phase flow of water have been carried out for local liquid Reynolds number (Re based on orifice diameter) ranging from 3 × 104 to 2 × 105 to obtain the discharge coefficient and the two-phase local multiplier, which when multiplied with the pressure drop of water (for same mass flow of water and two phase mixture) will reproduce the pressure drop for two phase flow through the orifice. The effect of orifice geometry on two-phase pressure losses has been considered by selecting two pipes of 60 mm and 40 mm inner diameter and eight different orifice plates (for each pipe) with two area ratios (σ = 0.73 and σ = 0.54) and four different thicknesses (s/d = 0.025–0.59). The results obtained from numerical simulations are validated against experimental data from the literature and are found to be in good agreement.

Autoignition Limits of Hydrogen at Relevant Reheat Combustor Operating Conditions

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
J. Fleck ◽  
P. Griebel ◽  
A.M. Steinberg ◽  
M. Stöhr ◽  
M. Aigner ◽  
...  
Keyword(s):  
Flue Gas ◽  
Gas Turbines ◽  
High Speed ◽  
Initial Position ◽  
Operating Conditions ◽  
Dominant Factor ◽  
High Speed Imaging ◽  
Lean Premixed Combustion ◽  
Fuel Jet ◽  
Image Velocimetry

The use of highly reactive fuels in the lean premixed combustion systems employed in stationary gas turbines can lead to many practical problems, such as unwanted autoignition in regions not designed for combustion. In the present study, autoignition characteristics for hydrogen, diluted with up to 30 vol. % nitrogen, were investigated at conditions relevant to reheat combustor operation (p = 15 bar, T >1000 K, hot flue gas, relevant residence times). The experiments were performed in a generic, optically accessible reheat combustor, by applying high-speed imaging and particle image velocimetry. Autoignition limits for different mixing section (temperature, velocity) and fuel jet (N2 dilution) parameters are described. The dominant factor influencing autoignition was the temperature, with an increase of around 2% leading to a reduction of the highest possible H2 concentration without “flame-stabilizing autoignition kernels” of approximately 16 vol. %. Furthermore, the onset and propagation of the ignition kernels were elucidated using the high-speed measurements. It was found that the ability of individual autoignition kernels to develop into stable flames depends on the initial position of the kernel and the corresponding axial velocity at that position. While unwanted autoignition occurred prior to reaching the desired operating point for most investigated conditions, for certain conditions the reheat combustor could be operated stably with up to 80 vol. % H2 in the fuel.

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