Suction Port Research Articles

Analysis of influencing factors on suction capacity in seabed natural gas hydrate by cutter-suction exploitation

The mathematical and simulation models of working head in the deep-sea working environment were built to analyze the effects of cutter-suction flow, cutter-head rotating speed, cutting depth and suction port position on the cutter-suction capacity. The efficiency of the cutter-suction is analyzed based on the analysis of the variation law of the solid-phase volume fraction of the flow field, the variation law of the velocity distribution in the flow field and the distribution law of the solid-phase concentration. The results show that the increase of cutter-suction flow can significantly improve the cutter-suction efficiency when it is less than 1000 m3/h. However, when it is more than 1000 m3/h, it is helpless. When the cutter-head rotate speed is within the range of 10–25 r/min, the cutter-suction efficiency stabilizes at about 95%. While the speed is greater than 25 r/min, the cutter-suction efficiency decreases sharply with the increase of cutter-head rotate speed. With the increase of cutting depth, the cutter-suction efficiency first increases and then remains stable and finally decreases. The cutter-suction efficiency remains at about 94% when the suction port position deviation ranges from 0° to 30°, but it has a sharply reduction when the deviation angle is more than 30°.

Hydroentanglement of polymer nonwovens. 1: Experimental and theoretical/numerical framework

Hydroentanglement is a versatile and important process used to form highly entangled nonwoven materials comprised of polymer fibers. It is a key element of polymer processing in the world, with the nonwovens market worth of tens of billions of the US dollars. No fundamental theoretical models of hydroentanglement were available so far, even though such modeling is required to facilitate the entirely empirical efforts to optimize the process. No model experiments on hydroentanglement aiming at its underlying physics were conducted either. These challenging problems are in focus in the present work. A model experiment is conducted and a quasi-one-dimensional model of individual polymer fibers is proposed and implemented for a number of fibers subjected to water jets impacting as a curtain normally to the nonwoven surface and undergoing filtration motion in the inter-fiber pores. The nonwoven is assumed to be located on a moving substrate with water suction through it. The model allows for a number of two-dimensional water jets and a number of suction ports in the substrate. The quasi-one-dimensional model allows for the three-dimensional motion of individual viscoelastic polymer fibers and the fiber-fiber interaction, which makes them non-self-intersecting. Then, the governing quasi-one-dimensional equations of fiber motion are discretized and solved numerically by using a discrete element method with mesh refinement of the Lagrangian mesh during the time marching. Using the developed code, several basic model problems were solved. Specifically, the behavior of several viscoelastic polymer fibers under the action of water jets with and without fiber-fiber interaction is described. Accordingly, a quantitative measure of the fiber-fiber entanglement is introduced based on the observed morphologies in the accompanying second part of this work.

Influence of suction port parameters on integral characteristics of screw-type compressor

At engineering screw-type machines different tasks on search for more effective and reliable design solutions arise connected with: organization of work process; selection of design shapes of the flow channel; strength calculation of machine components and selection of material. Considered in the work is enhancement of suction process efficiency by the use of dynamic head of the suction gas flow. Influence of rotor length to diameter ratio and suction port opening angle on integral characteristics of the compressor is considered. Calculation of work process in the compressor is performed by means of mathematical simulation. According to the work results it was determined that change in performance coefficient may reach 5%. At increase in suction port opening angle the leakage from compression cavities to a suction chamber increases and may reach 20%.

Diagnostic method by using vibration analysis for pump fault detection

Pump cavitation is a common problem affecting pumping systems. It occurs when the pressure of the liquid in the pump drops below a threshold and causes the liquid to vaporize creating tiny bubbles that, when they implode or collapse, trigger intense shockwaves inside the pump determining destructive damage. Excessive vibration on the pump casing could indicate cavitation. Consequently, vibration monitoring can help the detection and prevention of this harmful and undesired phenomenon.The purpose of this research is to analyze the capability of vibration-based techniques to detect, monitor and prevent pump cavitation. Experimental tests were performed on a gear pump used in the lubrication circuit of internal combustion engines. The pump, installed on a dedicated test bench, was forced to cavitate by placing a calibrated orifice on the suction side. Main working parameters, like oil flow rate, suction and delivery pressure, shaft speed, were accurately measured. Different pump operating conditions with and without cavitation occurrence were investigated through the use of a non-intrusive accelerometer, installed in proximity of the suction port so as to monitor the phenomenon in terms of vibration amplitude. A preliminary spectral analysis, based on the Fast Fourier Transform (FFT) of the vibrational signal, was performed in order to easily identify cavitation fundamental frequencies. A time-domain analysis technique was then implemented, aiming to realize an on line pump cavitation detection. Specifically, a NonLinear AutoRegressive (NLAR) approach based on the use of Artificial Neural Networks (ANN) was applied for modeling system behavior.In the paper, the results of the vibration-based method are discussed in depth, highlighting the pros and cons of the methodology. The presented outcomes demonstrate the ability of the proposed algorithm in accurately detect the presence of cavitation phenomena and to determine its intensity in pump real time operation. Hence, it may turn out to be a powerful tool for early detection of pumps incipient faults.

Safety and feasibility of above cuff vocalisation for ventilator-dependant patients with tracheostomies

Temporary tracheostomy is commonly used in patients admitted to intensive care units. Cuffed tubes prevent laryngeal airflow, preventing vocalisation. Sub-glottic suction tubes such as the 'Blue Line Ultra Suctionaid™' are used primarily to remove sub-glottic secretions, but retrograde gas flows via the suction port can facilitate above cuff vocalisation. The aims were to assess whether patients could achieve an audible voice using above cuff vocalisation, to demonstrate the safe use of the Blue Line Ultra Suctionaid™ tracheostomy tube for above cuff vocalisation, and to assess potential benefits of above cuff vocalisation for communication, secretion management and swallowing. Our study (Reference 15/NW/0464, IRAS 178997) recruited adult intensive care unit patients who were alert, able to participate in an above cuff vocalisation trial and dependent on an inflated Blue Line Ultra Suctionaid™ cuff for ventilatory support. Consenting participants underwent fibreoptic endoscopic assessment of swallow by experienced Speech & Language Therapy staff with and without above cuff vocalisation. Clinical and fibreoptic endoscopic assessment of swallow, assessment of voice quality, swallowing and secretion management were recorded and scored. Median differences between paired observations and scores were analysed with and without above cuff vocalisation. Adverse events were identified by follow up fibreoptic endoscopic assessment of swallow and patient accounts. Ten patients completed the study. Above cuff vocalisation was used for a median of 15 min, during a median of nine episodes, over a median of three days. Above cuff vocalisation resulted in an audible voice in eight of the 10 patients, during 66 out of 91 above cuff vocalisation attempts. There improvements in unstimulated dry cough and swallow frequency and aspiration ratings measured by fibreoptic endoscopic assessment of swallow. No complications were reported or observed in 66 attempts with only one episode terminated prematurely. Above cuff vocalisation can achieve effective, safe, well-tolerated vocalisation in ventilator-dependant intensive care unit patients. Above cuff vocalisation has the potential to aid earlier, more effective communication and may improve laryngeal function and rehabilitation.

Effect of Endotracheal Tube with Subglottic Suction Port vs Standard Endotracheal Tube on Incidence of Ventilator Associated Pneumonia in Patients of Organo-Phosphate Poisoning

Ventilator associated pneumonia is a hospital acquired infection that develops after 48 hours or more after a patient is intubated with an endotracheal or tracheostomy tube and is put on mechanical ventilation [1]. Ventilator associated pneumonia is most common nosocomial infection in ICU and associated with prolonged hospitalization, increased health care costs, and high attributable mortality. Intubation independently increases the risk of developing nosocomial pneumonia atleast seven fold with a peak incidence occurring around day five of ventilation [2]. Tracheal intubation thwarts cough reflex, compromises mucociliary clearance, injures tracheal epithelial surface, provides a direct conduct for rapid access of bacteria from upper into lower respiratory tract and allows formation of biofilm on Endotracheal tube surface. The combination of these factors puts mechanically ventilated patient at great risk of developing VAP. Aims and Objectives: To study incidence of VAP in ET tube with subglottic suction port versus standard ET tube in cases of O.P poisoning in J.J.M Medical college, Davangere from December 2015-June 2017. Material and Methods: A prospective observational case control study of 80 patients admitted to Red Zone/ICU of J.J.M. Medical College, Davangere. Results: Patients who have presented with Organophosphorous poisoning between the age group of 18 to 60 years who require ventilator support, intubated with standard ET tube and another sub set of patients intubated with ET tube with subglottic suction port were analysed. In this study we found that distribution of various organisms with regards to sputum culture in both groups were pseudomonas being maximum and proteus was found in minimum percentage. When subglottic suction port is used we observed improved patients were 70% and deaths were 30%. When subglottic suction port is not used we observed improved were 55% and death were 45%. Conclusion: VAP is common in patients who are intubated in ICU, which has higher morbidity and mortality among these patients. In our study we observed that atropine usually decreases secretions, but here in this study patient population who were admitted developed secretions instead of adequate atropine dosage and also developed VAP. Use of ET tube with Subglottic suction drainage may prevent VAP in cases of Organo Phosphorous poisoning and also improves patient outcomes.

Effect of Continuous versus Intermittent Subglottic Suctioning on Tracheal Mucosa by the Mallinckrodt TaperGuard Evac Oral Tracheal Tube in Intensive Care Unit Ventilated Patients: A Prospective Randomized Study.

Background and Aims:A risk of tracheal mucosa injury induced by subglottic suctioning has been raised. Therefore, this prospective randomized study aims to compare the effect of continuous suctioning of subglottic secretions versus intermittent suctioning of subglottic secretions (CSSS vs. ISSS) secretions on tracheal mucosa in front of the suctioning port of the endotracheal tube.Patients and Methods:Patients requiring intubation or reintubation in Intensive Care Unit with an expected ventilation duration > 24 h were eligible. Participants received CSSS at −20 mmHg or ISSS at −100 mmHg during 15 s and no suction during 8 s. The effect on tracheal mucosa in front of the suction port was assessed after intubation (T0) and before extubation (T1) using bronchoscopy. Tracheal mucosa damages were graded into five categories (no injury, erythema, edema, ulceration, or necrosis). The occurrence (no injury observed at T0 but present at T1) or the worsening (injury observed at T0 exacerbating at T1) was studied.Results:Seventy-three patients were included and 53 patients (CSSS, n = 26 and ISSS, n = 27) were evaluable on the primary endpoint. The occurrence or worsening of tracheal mucosal damages did not differ between the two groups (CSSS, n = 7 [27%] vs. ISSS, n = 5 [17%], P = 0.465). Daily average volume of suctioned secretion was higher with ISSS (74 ± 100 ml vs. 20 ± 25 ml, P < 0.001). Impossibility to aspirate was higher with CSSS (0.14 ± 0.16 per day vs. 0.03 ± 0.07 per day, P < 0.001).Conclusions:Our results suggest that tracheal mucosal damages did not differ between CSSS and ISSS. The aspirated volume was higher and impossibility to aspirate was lower with ISSS.Clinical Trial Registration:ClinicalTrials.gov Identifier: NCT01555229.

Effectiveness of Proseal laryngeal mask airway and laryngeal tube suction in elective non-laparoscopic surgeries of up to ninety minutes duration: A prospective, randomized study

Background and Aims:Proseal laryngeal mask airway (LMA) and laryngeal tube suction (LTS) are both supraglottic devices with an esophageal suction port. In the present prospective, randomized study, the effectiveness of airway seal, hemodynamic variables, ability to pass orogastric tube, and postoperative complications with the two devices were evaluated.Material and Methods:This was a prospective, randomized, single-blind study conducted in a hospital-based setting. Sixty patients (American Society of Anesthesiologists Grade I and II) undergoing elective general surgery were randomly allocated to Group A (Proseal LMA) or Group B (LTS), and airway seal pressure (primary outcome), peak pressure, hemodynamic parameters (blood pressure, pulse rate and pulse oximetry) during and 5 min after insertion, insertion time, ease of insertion, and postoperative complications (sore throat and hoarseness of voice for a period of 24 hours) (secondary outcomes) were noted. The quantitative data was summarized as mean and standard deviation, and analyzed using Student's t-test. All the qualitative data were summarized as proportions and analyzed using Chi-square test. The levels of significance and α-error were kept 95% and 5%, respectively, for all statistical analyses. P ≤ 0.05 was considered significant (S).Results:Proseal LMA had shorter insertion time (16.4 ± 5.6 vs. 20.0 ± 3.9 s), higher seal pressure (27.6 ± 4.6 vs. 24.1 ± 5.6 cm of H2O), lesser peak pressure (16.3 ± 2.3 vs. 18.5 ± 3.9 cm of H2O), higher success rate of orogastric tube passage (86.7 vs. 76.7%), and lesser postoperative sore throat (3.3 vs. 10%).Conclusions:Both Proseal LMA and LTS were acceptable alternatives for airway management in elective surgeries with controlled ventilation, but the quality of ventilation was found to be significantly better with Proseal LMA (in terms of higher seal pressure, lesser peak pressure, lesser insertion time, and lesser complications).

Would “suction above cuff” be a better option than the “standard” endotracheal tube for the prevention of ventilator-associated pneumonia: A randomized study in postoperative neurological patients

Context:Ventilator associated pneumonia is one the most common nosocomial infection encountered in the ICU patients. Despite of the implementation of the VAP prevention bundle, the incidence remains high. This can be attributed to the peritubal leak and the aspiration of the oropharyngeal secretions. The secretions further forms a nidus for the growth of organisms in the lower respiratory tract. In this study, a specialised tube, named ‘suction above cuff endotracheal tube’ is used, which has an additional suction port opening above the cuff. This is to facilitate timely aspiration of the secretion which pent-up above the cuff and gradually trickles down the trachea resulting in pneumonia.Aim:to compare the incidence of VAP with standard endotracheal tube (SETT) and suction above cuff endotracheal tube (SACETT) in neurological post-operative patients and its impact on clinical outcome.Settings and Design:60 patients of post-operative neurological cases aged ≥ 18 years and requiring intubation and/or ventilation and anticipated to remain on ETT for ≥48 h were randomized to receive either SETT or SACETT.Results:In this study involving neurological population, there was no significant difference in incidence of clinical and microbiological VAP between SETT and SACETT group, when other strategies for VAP prevention were similar. Other outcomes were similar with use of either tube for intubation.

Diagnostic Process by Using Vibrational Sensors for Monitoring Cavitation Phenomena in a Getoror Pump Used for Automotive Applications

A full experimental investigation on a Gerotor pump used for the lubrication of engines is described in this paper. These pumps, as well known, are widely used on engines for all hydraulic circuits and, for this reason, often they work in some conditions (such as at high speeds and pressure value) which are very challenging.In this paper one of the most unwanted phenomena that often occurs during the pump operation has been investigated: the cavitation.The cavitation can be triggered by many multiple factors such as the sloshing in the tank (translational and rotational motions), high percentage of gas dissolved in the fluid and pressure too low at the pump suction port. Therefore, the characterization of a Gerotor pump in cavitation condition is really interesting.In order to replay the cavitating conditions a pump has been installed on a dedicated test bench of the Department of Industrial Engineering of the university of Naples “Federico II”. The pump has been forced to cavitate by placing calibrated orifices on the suction side of the pump. Many decreasing diameters have been located in an aluminum connection block, to measure all the working parameters like the flow-rate, pressure (at the suction and delivery ports), pump speeds and pressure ripple. Cavitating and no-cavitating conditions have been investigated by using an accelerometer sensor in proximity of the pump suction chamber with the aim of monitoring the phenomena in terms of vibration amplitude.As afore mentioned, the pump under investigation has been studied in all operative conditions with and without cavitation phenomena by using a non-intrusive sensor like accelerometer in order to monitoring if cavitation is present.More precisely, the accelerometer sensor has been located close to the pump suction chamber and the vibrations have been acquired contemporarily with pressure signals (intake and outgoing discharge) and properly triggered with tachometer signal by using a multichannel acquisition system (Siemens™). A spectral vibration analysis has been used as diagnostic tool for accurately detecting pump degradation. The results coming from the analysis have shown that in presence of cavitation phenomena the non-intrusive monitoring technique represent a good diagnostic method for assessing pump operability.

Numerical analysis of the transient flow in a scroll refrigeration compressor

In the present paper, the CFD technology is adopted to simulate the working process of a scroll refrigeration compressor with R22 as working fluid. The structural grids in the scroll compressor were updated continually during the solving process to cope with the movement boundaries of the fluid domain. The radial meshing clearance was 0.008 mm which was the same with that in the real prototype. The pressure, velocity and temperature distribution in chambers of compressor were computed. Also, the transient mass flux diagrams were calculated out. The results indicated that the pressure was asymmetrical in the two symmetrical suction chambers, because the suction port and passage were not absolutely symmetrical. The gradient of temperature was great in each working chamber due to leakage flow. Velocity vector distribution was asymmetrical in each pair of working chamber owing to the movement of orbiting scroll; the flow was complicated in the central working chamber. The movement of the orbiting scroll had different influence on the vortexes formation in each pair of compression chamber. The inlet and outlet mass flux fluctuated with the crank angle obviously. Because of the ‘cut-off’ of the refrigeration fluid in the suction chamber when the crank angle was larger than 220°, the inlet mass flux decreased remarkably. Finally, some useful advices were given to improve the performance of the scroll refrigeration compressor.

Simulation study of multi-chamber rotary compressor

A new multi-chamber rotary compressor (MCRC) has been designed and the simulation result is presented in this paper. MCRC utilizes the space within the cylinder and it has the advantage of being more compact. Mathematical models which include geometrical, thermodynamics, mass flow and discharge valve have been formulated to evaluate the performance of MCRC. Parametric studies have also been carried out to determine the effects of design parameters such as suction and discharge ports size, valve length, valve thickness and valve width on compressor performance. In this paper, mathematical models will be presented and the predictions of the model will be shown and discussed.

Experimental Study of Suction Flow Control Effectiveness in a Serpentine Intake

The intakes of modern aircraft are subjected to ever-increasing demands in their performance. Particularly, they are expected to carry out diffusion with the highest isentropic efficiency while subjected to aggressive geometry requirements arising from stealth considerations. To avoid a penalty in engine performance, the flow through intake needs to be controlled using various methods of flow control. In this study, a serpentine intake is studied experimentally and its performance compared with and without boundary layer suction. The performance parameters used are nondimensional total pressure loss coefficient and standard total pressure distortion descriptors. The effect is observed on surface pressure distributions, and inferences are made regarding separation location and extent. A detailed measurement at the exit plane shows flow structures that draw attention to secondary flows within the duct. Suction is applied at three different locations, spanning different number of ports along each location, comprising of ten unique configurations. The mass flow rate of suction employed ranges from 1.1% to 6.7% of mass flow rate at the inlet of the intake. The effect is seen on exit total pressure recovery as well as circumferential and radial distortion parameters. This is examined in the context of the location of the suction ports and amount of suction mass flow, by the deviation in surface pressure distributions, as well as the separation characteristics from the baseline case. The results show that applying suction far upstream of the separation point together with a modest amount of suction downstream results in the best performance.

Numerical investigation on mass and heat transfer in an ammonia oil-free twin-screw compressor with liquid injection

Ammonia is one of the most frequently employed chemical materials, while oil-free screw compressors have recently been recognised as a quite suitable compression tool for an ammonia refinement system. In this paper, a heterogeneous model with mass and heat transfer was developed to investigate the characteristics of an ammonia screw compressor. The mass diffusion equation was solved based on the proper calculation of the physical properties of ammonia water mixtures. Then the model was validated by experimental data using a two-stage compression ammonia refining system. With validated simulation results, the impact of liquid injection on the compressor power consumption and temperature glide was then predicted and analysed. It was predicted that the isentropic efficiencies of the two compressors were 75% and 64% respectively. The simulation results revealed that the mean droplet diameter of the injected liquid should be less than 100 μm in order to guarantee sufficient cooling effect and improve the compressor performance. Finally, an optimization method for the location of injection nozzle and the amount of injected liquid was proposed. A second liquid injection nozzle is recommended to be added and located after the start point of compression process where the temperature glide is maximum. And the optimal flow rate of the new liquid injection nozzle is about 70% of the liquid amount injected to the suction port.

Effect of endotracheal tube with subglottic suction line to stop tracheostomy bleeding in critical patients

To observe the effect of endotracheal tube with subglottic suction line on tracheostomy bleeding in critical patients. This procedure was utilized for 35 critical patients with tracheostomy bleeding. With the help of bronchoscope, the endotracheal tube with subglottic suction line was inserted during tracheostomy to 0.5-1.0 cm above the carina. Then aerocyst of the tube was inflated, vacuum was set up for continuous suction via suction port, and hemocoagulase was injected to the opening of tracheostomy. The airway hemorrhage and treatment results were recorded. Tracheostomy bleeding in 33 patients (94.29%) were stopped. The bleeding time ranged from 6 to 48 hours with an average of (24.5±4.1) hours. The tube was in place for 2-10 days with a medium of 4 days. Using endotracheal tube with subglottic suction line for critical patients with tracheostomy bleeding is very effective. This procedure is also very simple and fast, and is best suitable for patient with heavy bleeding in tracheostomy.

CFD-based analysis of gas flow in dry scroll vacuum pump

Based on dynamics mesh method, Computational Fluid Dynamics (CFD) simulation model of two-stage dry scroll vacuum pump was established. Simulation calculation was carried out under the condition of suction pressure at 10000Pa, 1000Pa and 100Pa,respectively. When suction pressure was 10000Pa, the numerical calculation results were basically in accordance with the experimental pumping speed. When suction pressure decreased to 1000Pa, the simulation error decreased −5.7%. When suction pressure was below 1000Pa, due to the gas regime, the calculational results deviated from the experimental results dramatically. Three-scroll profile was applied to the scroll chamberⅠ connected with the suction port, which improved the pumping speed and compression ratio as well as reducing the fluctuation of suction speed significantly. Gas expanded initially in the chamber and was then compressed by external compression. Gas compression mainly occurred in scroll chamber Ⅱ connected with the exhaust port. Gas was compressed by changing the compression chamber. The variation of the pressure in compression chamber was greatly affected by gas leakage.

Early Replacement of Conventional Endotracheal Tube with Endotracheal Tube with Subglottic Suction port for the New Intensive Care Patients; Preventive or Problematic against Ventilator Associated Events?

Early Replacement of Conventional Endotracheal Tube with Endotracheal Tube with Subglottic Suction port for the New Intensive Care Patients; Preventive or Problematic against Ventilator Associated Events?

전산유체역학(CFD) 분석법을 이용한 High Wind Velocity/High Drying Time 헤어드라이어의 개발

This paper describes a design of a hair drier to improve its performance. the performance of the hair drier can be improved by increasing the wind velocity of its discharge port. the design of the hair drier is accomplished by using the CFD. the validity of design results were verified by comparison with the dry change of the hair drier. In this paper, the initial condition of the applied hair drier is as follows, the number of the blade is 9, the diameter of the suction port is 40[mm], the tip clearance is 12.5[mm], the con angle is 28.5° and the fan angle is 27.5R. From design results, the enhanced condition of the hair drier can be obtained as follows, the number of the blade is 3, the diameter of the suction port is 50[mm], the tip clearance is 10.5[mm], the con angle is 21.5° and the fan angle is 75R. At the enhanced condition of the hair drier, the wind velocity of the hair drier is 29[%] increase, and the dry time is 40[%] increase compare to the initial condition of the hair drier.

Gerotor pump cavitation monitoring and fault diagnosis using vibration analysis through the employment of auto-regressive-moving-average technique

Gerotor pumps, as well known, are widely used in lubrication circuits of internal combustion engines for their simplicity, high efficiency and low costs.In this paper an experimental characterization of a Gerotor pump is shown. The research is a collaboration between the Hydraulic Power Research Group (HPRG) of the University of Naples “Federico II” and the Istituto Motori of CNR.The aim of this research is to investigate the possibility of using simple data to acquire, as vibrational data, on the pump under investigation to detect possible cavitation problem by implementing a proper mathematical procedure to this aim. As been demonstrated that these pumps are particularly subject to cavitation.The gerotor pumps are much subject to cavitate than expected, especially under particular operating conditions of the engine. Cavitation is also correlate to vehicle dynamics particularly with the recent tendency to reduce the mass of oil in the sump. Therefore, the research to avoid cavitation is crucial nowadays. Consequently this study has been firstly performed with an experimentation on the pump by monitoring the delivered oil flow-rate and the adsorbed torque on the pump shaft. An accurate analysis of the pressure oscillations in cavitation conditions, has been, also, conducted. Then, an accelerometer sensor has been properly located to study the cavitation with a fault diagnosis system based on vibration detection.The experimental tests have been performed on a test bench of the Hydraulic Laboratory of the University of Naples “Federico II” in Italy. The bench allows testing the pump working by varying the shaft speed, the oil temperature, the suction and the delivery pressure. The main measured parameters are shaft torque, oil flow rate, mean suction and delivery pressure and the instantaneous suction and delivery pressure.As expected, tests revealed the high influence of the suction pressure on the delivered oil flow rate, while no significant influence has been noted on the adsorbed torque. Furthermore, the pressure oscillations in the pump delivery are highly influenced by the suction pressure.A non intrusive accelerometer has been installed during the experimentation on the oil pump. Since the vibration due to cavitation is the main concern of this study, the accelerometer has been mounted at the suction port in the radial direction.More precisely, the paper presents a fault diagnosis system based on vibration detection. Firstly, a Fast Fourier Transform of the vibration signal has been computed. The investigation has been made with and without the presence of cavitation varying the pump rotation speeds. Limitations due to the detecting of the on line cavitation problems by monitoring the FFT vibration spectra have been overcame by implementing an alternative method based on stochastic approach.This diagnosis method of accelerometer time series analysis based on an Auto Regressive and Moving Average (ARMA) method has been used to determine the pump failure. The diagnosis results have demonstrated the ability of the proposed mathematical technique in the identification of cavitation phenomena proving that the proposed approach is a useful methodology to detect the presence of fault. The approach can predict, with good accuracy, pump failure in real time operation. In addition, a threshold vibration level in decibel scale is also fixed.

Suction port design for a synchronal rotary multiphase pump

The synchronal rotary multiphase pump is a new type of positive-displacement pump for multiphase boosting. Given that the discharge valve is eliminated in the synchronal rotary multiphase pump, the radial suction port as used in traditional rotary compressors is no longer suitable for the gas–liquid working condition. Thus, a special design for the axial suction port is presented to ensure the synchronal rotary multiphase pump’s flexibility in handling work fluids with any inlet gas volume fraction. The design concept and working principle of the axial suction port of the synchronal rotary multiphase pump are introduced herein, and a geometrical model of the suction port is established to calculate the critical dimensions for the synchronal rotary multiphase pump manufacture. The results show that the axial suction port’s design avoids the inner compression of work fluids and the back flow from the outlet to the inlet of the synchronal rotary multiphase pump during operation, which meets the requirements for operating under the gas–liquid working condition. The matching between the variation in the sectional area of the suction port and the varying trend of suction volume results in an acceptable sectional velocity of suction flow. Although the designed axial suction port reduces the suction angle range in a revolution, the decrease in the volumetric efficiency is negligible.