Orifice Design Research Articles

Obstacle contained system (OCS) design method and its application in valve core orifice design of pilot-control globe valve

With the development of the society and the times, traditional parametric design methods are witnessing a severe challenge due to the more and more complex physical systems. Thus, developing novel parametric analysis methods is very important for dealing with complex physical systems, refining useful parameters from numerous data, and proposing accurate prediction formulas. A spring slider system, a direct-current circuit system, a pipeline pressure drop system and a steady heat transfer model of flat plate system were described from the point of systemic parametric analysis method. Then, the key physical parameters in above four systems were summarized. Based on the comparative results, a novel systemic parametric design method, obstacle contained system (OCS) design method, was proposed. The OCS was made up of three elements:an obstacle element, a pass body element and a D-value element. With an abundant accurate data pole, the OCS design method could build the direct relationship of the obstacle element and the D-value element, which meant the simplification of the physical models and much easier to get relatively accurate results. Meanwhile, the design of pilot-control globe valve orifice was checked with both the OCS design method and the numerical simulation. The diameter of orifice on the valve core could influence the pressure difference and the maximum vapor rate inside pilot-control globe valves. Achieved by two different methods, the OCS design method and the numerical simulation, the results showed that the effects of orifice diameters on the pressure difference and the maximum vapor rate under different inlet velocities, were within 2% errors, which was reasonable and acceptable for the engineering application. In other words, the OCS design method was credible for parametric analysis. In future, the OCS design method has a broad application prospect to analyze various types of physical models especially in the era of big data.

Research on the injected effect by the narrow-slit injection orifice in screw compressors

A narrow-slit injection orifice in screw compressors (mainly in single screw compressors) is described in this paper. In contrast to the traditional injection orifice, the section is slit shaped but not circular. Liquid which is injected by the narrow-slit injection orifice appears as a curtain shape. The heat transfer area is increased so that the cooling effect is enhanced and the efficiency of the compressor is improved. The injected effect was simulated through the CFD software, and then the experiments were carried out. The study verified the accuracy of the simulation results and will provide a theoretical foundation for the design of a narrow-slit injection orifice in screw compressors.

Computational fluid dynamics analysis on orifice structure inside valve core of pilot-control angle globe valve

A novel pilot-control angle globe valve is proposed, and it has an obvious advantage of energy conservation during its opening and closing process. In pilot-control angle globe valve, the opening and closing forces are related to the orifice located inside the valve core. In this paper, the effects of orifice diameter are thoroughly studied under different working conditions such as valve core displacements and inlet velocities. To begin with, the numerical model is validated by comparing similar angle valves, and then the flow and loss coefficients under different orifice diameters are discussed. It is found that the effects of orifice diameter on force acting on valve core depend on valve core displacement and inlet velocity. Thus different valve core displacements and inlet velocities combined with different orifice diameters are further studied. It is also found that when the orifice diameter is larger than 12 mm, pilot-control angle globe valve cannot be used under small inlet velocity or large valve core displacement. In addition, formulas to calculate forces on valve core are proposed for further orifice design. This work can be referred in process industries especially in a piping system with orifice plates or globe valves.

Controlling the hydration rate of a hydrophilic matrix in the core of an intravaginal ring determines antiretroviral release

Intravaginal ring technology is generally limited to releasing low molecular weight species that can diffuse through the ring elastomer. To increase the diversity of drugs that can be delivered from intravaginal rings, we designed an IVR that contains a drug matrix encapsulated in the core of the IVR whereby the mechanism of drug release is uncoupled from the interaction of the drug with the ring elastomer. We call the device a flux controlled pump, and it is comprised of compressed pellets of a mixture of drug and hydroxypropyl cellulose within the hollow core of the ring. The pump orifice size and chemistry of the polymer pellets control the rate of hydration and diffusion of the drug-containing hydroxypropyl cellulose gel from the device. A mechanistic model describing the hydration and diffusion of the hydroxypropyl cellulose matrix is presented. Good agreement between the quantitative model predictions and the experimental studies of drug release was obtained. We achieved controlled release rates of multiple antiretrovirals ranging from μg/d to mg/d by altering the orifice design, drug loading, and mass of pellets loaded in the device. This device could provide an adaptable platform for the vaginal drug delivery of many molecules.

A Study on Synthetic Jet Actuator Diaphragm

A synthetic jet actuator (SJA) is one of the most widely used active flow control device which uses a vibrating diaphragm enclosed within a cavity to generate the fluid jet. The effectiveness of the actuator greatly depends upon the design of cavity and orifice and the diaphragm properties. A lot of emphasis is being laid on the cavity and orifice design, but very few literatures can be found dealing with the diaphragm of the SJA. Thus, in this paper a study of the SJA diaphragm actuated by piezoelectric ceramics of different geometries is being presented. Three different diaphragm materials — brass, poly-silicon and aluminum and five different geometries of the piezoelectric actuators — annular disc shaped actuator patch, annular shaped actuator, rectangular shaped actuator patch and circular disc shaped actuator patch and two cantilever arrangements are being considered. A static analysis is carried out and a comparison of the parameters which affect the performance of the SJA is done. Frequency response analysis is also carried out to obtain a better understanding of the diaphragm's structural characteristics. The results thus obtained show that an annular disc piezoelectric patch configuration shows the best behavior as compared to the other actuator configurations and is closely followed by circular disc piezoelectric patch configuration.

Influence of Plasma Torch Nozzle Design on Plasma Arc Analyzed with Finite Element Method

Plasma torch is one of the most important parts for plasma arc generating system. A design of orifices in a nozzle would decide the properties of plasma arc. However, mechanisms of orifice to plasma arc are seldom discussed. In this paper, the plasma arc with two assistant orifices were analyzed by finite element method. It was concluded that the plasma arc would be further compressed in the direction parallel to two assistant orifices, but expand perpendicular to assistant orifices. Through the constriction of two assistant orifices, the shape of the plasma arc would be elliptical other than circular of the oridinary plasma arc. The torch design with two assistant orifices could be available to many fields such as plasma arc welding, especially to a welding torch with a large pressure chamber.

Design of a rotary valve orifice for a continuous wave mud pulse generator

High-speed downhole transmission technology plays an important role in measurement while drilling (MWD) and logging while drilling (LWD) systems, where the continuous wave mud pulse transmission method is currently the most advantageous method for wireless downhole transmission. To increase the production rate, transmission distance and testing intensity and to decrease the ground detected difficulty of continuous wave mud signals, the valve orifice must be optimized to satisfy the requirements for the continuous sinusoidal pressure output. In this study, an improved arc-fillet-line triangular valve orifice is designed based on a general line triangular valve orifice according to the relationships between the fluid differential pressure of a thin-walled cutting edge and the fluid flow area and between the correlation coefficient of the theoretical pressure difference and standard sinusoidal signal. The improved orifice is designed by calculating the variation between the flow area and relative rotation angle of the rotor to the stator through the established polar coordinate equations. The optimized valve structure is simple and easy to machine, and highly similar sinusoidal pressure wave signals can be achieved during practical operation to meet the requirements of the instrument design.

Effect of orifice geometry on bubble formation in melt gas injection to prepare aluminum foams

The bubble formation process at submerged orifices with different geometry is investigated in the preparation of aluminum foams by gas injection method. The bubble profile on a horizontal plate is calculated by quasi-static analysis through Laplace equation. The bubble formation process is then distinguished into three stages: nucleation stage, growth stage and detachment stage in wetting and less wetting conditions based on the force balance analysis. In addition, the bubble size at high Reynolds number is obtained by considering the contribution of buoyancy, pressure force, inertial force, drag force and surface tension based on the three stages of bubble formation. The bubble size is confirmed to be sensitive to the equivalent contact angle, which consists of two terms including the contact angle and the wedge angle. Therefore, the wedge angle is introduced in the design of gas outlet orifices for the purpose of decreasing bubble size generated. The experimental study is conducted at three different types of stainless steel orifices under constant gas flow rates (0.05–2 L/min). It is clarified that the orifice geometry and the orifice size are both responsible for the cell size of aluminum foams. The experimental results for three different types of orifices show a consistent trend with the theoretical predictions at various gas flow rates. In the design of orifices to generate small bubbles in the melt, the wedge angle that coordinates with the contact angle is thus suggested.

Design and Development of Online Steam Dryness Fraction Measurement Setup

The aim of study is to develop highly reliable and less time consuming steam dryness fraction measuring experimental setup. This method of dryness fraction measurement is based on throttling process which is obtained by using orifice plate. Calculation of orifice diameter was done by using ISO 5167 for given pressure drop. This paper deals with the conceptual design of orifice in a steam pipe line. The objective of the conceptual design is to obtain throttling process. Three parameters are chosen for the conceptual design: the diameter of the orifice, the aspect ratio between length and diameter and the entrance angle to the orifice. This work also deals with validation of calculated orifice diameter through CFD simulation for pressure drop in pipe line. To simulate the throttling process, the inlet condition of the orifice upstream flow is fixed at 10 bar and 180°C. The temperature and pressure is measured at the outlet of the orifice while steam is flowing through the pipe. An orifice diameter of 11.00mm is selected as the optimal value to keep throttling process. The resulting optimal orifice design will be used in steam pipe line.

Modelling of fluid flow through short tube orifices under metastable conditions: A new numerical validation approach for evaluating the mass flow rate with refrigerant mixtures (HFC-407C and HFC-410A)

In a previous work, one-dimensional numerical modelling of fluid-flow inside short tube orifices was performed, and successfully validated against a wide range of mass flow rate measurements reported for the refrigerant HFC-134a. Governing equations of continuity, momentum, energy and entropy were solved for describing the fluid flow under a wide variety of thermodynamic transitions (e.g., subcooled liquid region, metastable liquid region, metastable two-phase region and equilibrium two-phase region), including sudden contraction and enlargement. In this new study, a comprehensive comparison analysis between numerical simulation data and experimental measurements obtained for HFC-407C and HFC-410A refrigerants (No = 241) to extend the applicability of the same mathematical model was carried out. Using a widespread statistical analysis, based on weighted linear regressions with an outlier detection/rejection module at 95% of confidence level, the prediction performance of the mathematical model was again assessed. Linear regressions between predicted mass flow rate data and experimental measurements were computed, and used them as a statistical comparison criterion. A statistical comparison between predicted simulation results and mass flow rate experimental data are reported. Average deviation errors of ±11.1% (for the refrigerant HFC-407C) and ±7.3% (for refrigerant HFC-410A) were found between numerical model and experimental data. These results demonstrate a new and robust application of the model to predict reliably the mass flow rate through short tube orifices under metastable conditions, which enable this tool to be reliably used for the design of short tube orifices.

Designing Aerostatic Bearing With Counterbalancing Gaps for Lifting a Heavy Payload

An aerostatic bearing has been designed for supporting a heavy payload. The bearing involves an axial gap on the stator top that provides an upward lift, a bottom gap for counterbalancing the tendency of large lift-off, and a feeding orifice at the bearing inlet that is connected with the gaps by a network of holes or inherences yielding the damping. Notable contributions of the work are proving the concept by numerical simulation through first-principle order-separated modeling and evolving a simple solution strategy. The predicted vertical motion dynamics of the payload reveals that, depending on the target range of the payload weight, alternatives could be free or choked orifice designs.

Swirl Atomizer Design for Evaporative Cooling of High Temperature Compressed Air Stream

Faculty of Mechanical EngineeringGIK Institute of Engineering Sciences and Technology,PakistanThis work presents the design of a swirl atomizer which provides a certainflow rate of water with required spray quality for effective evaporative cooling ofhigh temperature compressed air of a turbocharged diesel engine. By using wetcompression theoretical model, the desired mass flow rate of water and qualityof spray for effective evaporation was determined. The evaporative cooling de-creases the intake air temperature of engine and increases its mass flow rate, withconstant fuel-to-air ratio this increase in air mass flow rate increases the powerof the engine. Abramovich’s theory along with Kliachko’s theory was followedto design a swirl atomizer that provides the required spray characteristics. In-formation has been presented on the effect of atomizer inlet port geometry, swirlchamber design, orifice design and the importance of swirling inside atomizer.The effects of atomizer geometric parameters such as angle of conical conver-gence, length-to-diameter ratio of inlet port and of swirl chamber were examined.It was concluded that the length-to-diameter ratio of swirl chamber has a signif-icant effect on atomizer flow rate and spray cone angle determination. With thesame injection pressure, its increase leads to enhancing the mass flow rate whiledecreasing the spray cone angle from the atomizer. The atomizer was tested ex-perimentally and through fluid flow modeling for its required spray quality andthe results were fairly close with theoretically predicted results. The design ofatomizer was also optimized for required spray characteristics by modeling thefluid flow inside the atomizer.* * *

A Modified Particle Swarm Optimization Algorithm for the Design of a Double-Pad Aerostatic Bearing With a Pocketed Orifice-Type Restrictor

The performance of an aerostatic bearing with a pocketed orifice-type restrictor is affected by the bearing size, pocket size, orifice design, supply pressure, and bearing load. This study proposes a modified particle swarm optimization (MPSO) algorithm to optimize a double-pad aerostatic bearing. In bearing optimization, the upper and lower bearing designs are independent and several design variables that affect bearing performance must be considered. This study also applies the concept of mutation from a genetic algorithm. The results show that the MPSO algorithm has a global search capability and high efficiency to optimize a problem with several design variables and that the mutation can provide an avenue for particles to escape from a local optimal value.

The Influence of Actuator Materials and Nozzle Designs on Electrostatic Charge of Pressurised Metered Dose Inhaler (pMDI) Formulations

To investigate the influence of different actuator materials and nozzle designs on the electrostatic charge properties of a series of solution metered dose inhaler (pMDI) aerosols. Actuators were manufactured with flat and cone nozzle designs using five different materials from the triboelectric series (Nylon, Polyethylene terephthalate, Polyethylene-High density, Polypropylene copolymer and Polytetrafluoroethylene). The electrostatic charge profiles of pMDI containing beclomethasone dipropionate (BDP) as model drug in HFA-134a propellant, with different concentrations of ethanol were studied. Electrostatic measurements were taken using a modified electrical low-pressure impactor (ELPI) and the deposited drug mass assayed chemically using HPLC. The charge profiles of HFA 134a alone have shown strong electronegativity with all actuator materials and nozzle designs, at an average of -1531.34 pC ± 377.34. The presence of co-solvent ethanol significantly reduced the negative charge magnitude. BDP reduced the suppressing effect of ethanol on the negative charging of the propellant. For all tested formulations, the flat nozzle design showed no significant differences in net charge between different actuator materials, whereas the charge profiles of cone designs followed the triboelectric series. The electrostatic charging profiles from a solution pMDI containing BDP and ethanol can be significantly influenced by the actuator material, nozzle design and formulation components. Ethanol concentration appears to have the most significant impact. Furthermore, BDP interactions with ethanol and HFA have an influence on the electrostatic charge of aerosols. By choosing different combinations of actuator materials and orifice design, the fine particle fractions of formulations can be altered.

Implementation of multi-opening orifices in the primary metrology of vacuums and small gas throughputs

A multi-opening orifice is a device for the primary measurement of gas flows and related vacuum quantities. This device maintains a constant molecular flow regime and thus the possibility to very accurately calculate the conductance from the geometrical dimensions for relatively high pressures, and the value of the conductance is sufficiently high to achieve reasonable parameters of the vacuum system in use. Suitable shapes of a multi-opening orifice duct and the principles of multi-opening orifice design are discussed. An example of the multi-opening orifice manufactured with grinding is given. The limits and requirements for further development are drafted.

Design and test of annular discharge orifice of shock transmission unit

The annular discharge orifice is a key parameter for the design of a shock transmission unit (STU). The proper dimension of the annular discharge orifice can make the stiffness difference of STU maximum in different conditions. Making use of three laws of fluid mechanics, the mathematical model for designing annular discharge orifice was developed. The STUs were subjected to the slow movement test, the fast movement test and the simulated dynamic test. During the slow movement test, the resistance force does not exceed 10% of the nominal rated force; during the simulated dynamic test, the deflection between the point of zero load and the point of maximum load does not exceed 12 mm, and the deflection during the sustained load portion of the test does not exceed 12 mm; during the fast movement test, the force can maintain the nominal rated force. The validity of the mathematical model is verified by these testing, and the mathematical model can instruct the design of annular discharge orifice of STU.

Comparison between the effects of single-pad and double-pad aerostatic bearings with pocketed orifices on bearing stiffness

This study compares the stiffness of the single-pad and the double-pad aerostatic bearings with pocketed orifices. The stiffness comparison is based on the given loads, which provide useful information for bearing design. Bearing design parameters include supply pressure, pocket size, orifice design, and applied load. Therefore, the analysis of double-pad aerostatic bearings is complex because of the independent design of upper and lower bearings. Results show that a double-pad aerostatic bearing with the same upper and lower bearing is not the best design and that double-pad aerostatic bearings have higher stiffness than the single-pad aerostatic bearings.

On Orifice Design for Reducing Self-Excited Vibration of Aerostatic Guideway

Aerostatic guideway is an essential sub-system for high-accuracy measurement. As compressible air is used for suspension, several problems arise aside of its other advantages. The most important aspect that should be taken into consideration is self-excited vibration activated by inner or/and outer environments. This paper discusses how the orifice layouts and the orifice diameter affect the self-excited vibration of the aerostatic guideway, or two-dimension x-y stage as a whole. Theoretical formulas for flow coefficient of orifices are obtained and experiment of differential pressure test is conducted. Both theoretical and experimental approaches of aerostatic guideway design and characteristics of vibration attenuation are proposed in this research. The results show that by optimizing orifice diameter and orifice layouts, good effect on reduction of self-excited vibration can be achieved, with the time of vibration attenuation reduced from 1.8s to 0.9s.

Performance of inherently compensated flat pad aerostatic bearings subject to dynamic perturbation forces

The importance of air bearing design is growing in engineering. As the trend to precision and ultra precision manufacture gains pace and the drive to higher quality and more reliable products continues, the advantages which can be gained from applying aerostatic bearings to machine tools, instrumentation and test rigs is becoming more apparent. The inlet restrictor design is significant for air bearings because it affects the static and dynamic performance of the air bearing. For instance pocketed orifice bearings give higher load capacity as compared to inherently compensated orifice type bearings, however inherently compensated orifices, also known as laminar flow restrictors are known to give highly stable air bearing systems (less prone to pneumatic hammer) as compared to pocketed orifice air bearing systems. However, they are not commonly used because of the difficulties encountered in manufacturing and assembly of the orifice designs. This paper aims to analyse the static and dynamic characteristics of inherently compensated orifice based flat pad air bearing system. Based on Reynolds equation and mass conservation equation for incompressible flow, the steady state characteristics are studied while the dynamic state characteristics are performed in a similar manner however, using the above equations for compressible flow. Steady state experiments were also performed for a single orifice air bearing and the results are compared to that obtained from theoretical studies. A technique to ease the assembly of orifices with the air bearing plate has also been discussed so as to make the manufacturing of the inherently compensated bearings more commercially viable. (c) 2012 Elsevier Inc. All rights reserved.

오리피스 형상에 따른 발사관 내 부가추력 특성 연구

If the flow of booster gas which is exhausted to the rear part of a canister is properly restricted in the canister of a hot-launch system, the resultant pressure built up in the canister provides additional force to accelerate the missile to a required launch velocity. These thrust augmentation performances can be controlled through the configuration design of baseplate orifices. In this paper, the simple technique to analyze the thrust augmentation performances of baseplate orifices is suggested and the thrust augmentation characteristics by its various configurations are compared. According to the initial displacement of a missile, the inner pressure of a canister is measured from scaled cold flow tests, and the discharge coefficient of baseplate orifices is calculated. Then the thrust augmentation in a canister is simulated by applying these discharge characteristics to the AMESIM software for launch dynamics.