Bleed Port Research Articles

Influence of bleeding positions in self-recirculating casing treatments on the stability of a subsonic axial compressor

Influence of bleeding positions in self-recirculating casing treatments on the stability of a subsonic axial compressor

Design and Analysis of Fixed Brake Caliper using Additive Manufacturing

Abstract: The brake caliper's function is to channel the mechanical force generated by the driver's mechanical action on the brake master cylinder—pressurized fluid—into an outward force that may be directed to the car's brake rotors. The effectiveness of the brakes plays a significant role in a vehicle's performance, and the design of the caliper may be improved by taking into account elements like the bleeding port, the brake pads, and the fluid flow path. As two-wheeler calipers are often used in automobiles, the entire system must be dismantled, bled, and then reassembled involved halves. Custom calipers have been employed by commercial automakers to cut back on the extra work involved in developing and producing RH and LH calipers. This project aims of this project are to create, evaluate, and maybe construct a front brake caliper prototype for the Formula Student cars. The desired outcome would be for the brake caliper to outperform all of the "firms" and set us apart from the other competing teams. Additive manufacturing is a new and rapidly developing manufacturing method. The current manufacturing processes for brake calipers separate components assembler.

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Introduction: Major bile duct injury in laparoscopic cholecystectomy results in morbidity and needs further management, which adds to the increased cost of treatment. However, some studies have shown that by defining critical view of safety and seeing the relationship of Rouviere's sulcus with other structures, and minimal use of diathermy in Calot's triangle, we can bring down complications further close to zero percent. We wanted to see that such a low bile duct injury rate is achievable at every center by routinely following these steps. We retrospectively reviewed the database of patients who had undergone elective laparoscopic cholecystectomy (LC) in three years and evaluated the rate of bile duct injury and other complications. Methods: We reviewed our database for patients and did a retrospective analysis on patients who were diagnosed with symptomatic cholelithiasis or chronic cholecystitis, and have undergone LC in our centre from January 2017 to December 2019. Patients less than 15 years of age, acute cholecystitis, and laparoscopic cholecystectomy combined with common bile duct exploration were excluded. We calculated the incidence of biliary injury. The secondary outcomes looked at were Veress needle or pneumoperitoneum-related complications, port site bleeding, intra-abdominal bleeding, bowel injury, liver injury, wound infection, and early port site hernia. Results: LC was performed in 642 patients. In this study, there was no bile duct injury. Two patients (0.31%) had minor bile leak which resolved without any intervention within a week. Three (0.46%) patients developed port site infection, which responded to regular dressing and oral antibiotic therapy. Conclusion: The effectiveness of these steps should make their use mandatory in every center to reduce bile duct injury.

Inter-Stage Dynamic Performance of an Axial Compressor of a Twin-Shaft Industrial Gas Turbine

In this study, the inter-stage dynamic performance of a multistage axial compressor is simulated through a semi-empirical model constructed in the Matlab Simulink environment. A semi-empirical 1-D compressor model developed in a previous study has been integrated with a 0-D twin-shaft gas turbine model developed in the Simulink environment. Inter-stage performance data generated through a high-fidelity design tool and based on throughflow analysis are considered for the development of the inter-stage modeling framework. Inter-stage performance data comprise pressure ratio at various speeds with nominal variable stator guide vane (VGV) positions and with hypothetical offsets to them with respect to the gas generator speed (GGS). Compressor discharge pressure, fuel flow demand, GGS and power turbine speed measured during the operation of a twin-shaft industrial gas turbine are considered for the dynamic model validation. The dynamic performance of the axial-compressor, simulated by the developed modeling framework, is represented on the overall compressor map and individual stage characteristic maps. The effect of extracting air through the bleed port in the engine center-casing on transient performance represented on overall compressor map and stage performance maps is also presented. In addition, the dynamic performance of the axial-compressor with an offset in VGV position is represented on the overall compressor map and individual stage characteristic maps. The study couples the fundamental principles of axial compressors and a semi-empirical modeling architecture in a complementary manner. The developed modeling framework can provide a deeper understanding of the factors that affect the dynamic performance of axial compressors.

Gellable silk fibroin-polyethylene sponge for hemostasis

Traditional haemostatic materials generally have slow hemostasis rate and poor biocompatibility. This paper reports on the haemostatic properties and mechanism of silk fibroin (SF). SF-PEG sponge that could be solubilised and changed to gel form by blood was fabricated through mixing SF and polyethylene glycol (PEG, 1500 Da) followed by lyophilisation of the mixed solution. SF-PEG sponge, together with control samples of SF sponge (no PEG) and a commercially available haemostatic material, gelatine sponge, were subjected to the hemostasis tests using a liver trauma model of rabbit. The results showed that SF was superior to gelatine sponge in hemostasis time (136.17 ± 62.27 s and 249.83 ± 29.18 s) and blood loss (2.16 ± 1.27 g vs. 4.97 ± 1.44 g). Furthermore, in vitro experiments indicated SF-PEG sol-gel transition promoted platelet adhesion and aggregation, as well as platelet-fibrinogen interaction. Therefore, except for the physical blocking of bleeding port due to PEG-induced SF fast gelation, SF might also have an impact on blood coagulation process, a phenomenon that has not been reported before. In conclusion, SF is a new type of haemostatic material that might be able to meet the requirements of speed, efficiency and biosafety in a variety of clinical applications.

Experimental investigation of the casing treatment effects on steady and transient characteristics in an industrial centrifugal compressor

In this paper, a method of holed casing treatment is put forward and applied to an industrial centrifugal compressor. A series of experimental investigations are conducted to study the effects of casing treatment on steady and transient performance of the compressor. Dynamic pressure is monitored under stable operating point and surge occurrence condition at following positions: two ends of the treated holes, 37%-chord impeller tip position and the vaneless diffuser. By use of the casing treatment, the surge margin of the compressor is increased by about 10%Qdesign with negligible decrease in efficiency. Pulsating pressure change is taken as an indicator for evaluating the flow direction in the hole. Near surge point, when the static pressure of the bleeding port is larger than the turning point, a sudden increase in pulsating pressure indicates that the bleeding flow occurs. Near choke side, when the static pressure of the turning point is larger than the bleeding port, a severe change in pulsating pressure indicates that the bypass flow occurs. Signal analysis of the dynamic pressure at surge occurrence shows that the compressor stalls with a modal inception rather than a spike wave no matter casing treatment is applied or not. The travelling speed of the stall cell found in the compressor with casing treatment is faster than that with solid casing. The occurrence of modal precursor wave is delayed with casing treatment.

Numerical Study of Aerodynamic Losses of Effusion Cooling Holes in Aero-Engine Combustor Liners

Due to the stringent cooling requirements of novel aero-engines combustor liners, a comprehensive understanding of the phenomena concerning the interaction of hot gases with typical coolant jets plays a major role in the design of efficient cooling systems. In this work, an aerodynamic analysis of the effusion cooling system of an aero-engine combustor liner was performed; the aim was the definition of a correlation for the discharge coefficient (CD) of the single effusion hole. The data were taken from a set of CFD RANS (Reynolds-averaged Navier-Stokes) simulations, in which the behavior of the effusion cooling system was investigated over a wide range of thermo/fluid-dynamics conditions. In some of these tests, the influence on the effusion flow of an additional air bleeding port was taken into account, making it possible to analyze its effects on effusion holes CD. An in depth analysis of the numerical data set has pointed out the opportunity of an efficient reduction through the ratio of the annulus and the hole Reynolds numbers: The dependence of the discharge coefficients from this parameter is roughly linear. The correlation was included in an in-house one-dimensional thermo/fluid network solver, and its results were compared with CFD data. An overall good agreement of pressure and mass flow rate distributions was observed. The main source of inaccuracy was observed in the case of relevant air bleed mass flow rates due to the inherent three-dimensional behavior of the flow close to bleed opening. An additional comparison with experimental data was performed in order to improve the confidence in the accuracy of the correlation: Within the validity range of pressure ratios in which the correlation is defined (>1.02), this comparison pointed out a good reliability in the prediction of discharge coefficients. An approach to model air bleeding was then proposed, with the assessment of its impact on liner wall temperature prediction.

Simulation of Shock/Boundary-Layer Interactions with Bleed Using Immersed-Boundary Methods

This work utilizes an immersed boundary (IB) method to simulate the effects of arrays of discrete bleed ports in controlling shock wave / turbulent boundary layer inter actions . Both Reynolds averaged Navier -Stokes (RANS) and hybrid large -eddy / Reynolds -averaged Navier -Stokes (LES/RANS) turbulence closures are used with the IB technique. The approach is validated by conducting simulations of Mach 2.5 flow over a perfo rated plate containing 18 individual bleed holes. Predictions of discharge coefficient as a function of bleed plenum pressure are compared with experimental data. Simulations of an impinging oblique shock / boundary layer interaction at Mach 2.45 with an d without active bleed control are also performed. The 68 -hole bleed plate is rendered as an immersed object in the computational domain. Wall pressure predictions show that, in general, the LES/RANS technique under -estimate s the upstream extent of axi al separation that occurs in the absence of bleed. Good agreement with P itot -pressure surveys throughout the interaction region is obtained, however. Active suction completely removes the separation region and induces local disturbances in the wall pres sure distributions that are associated with the expansion of the boundary layer fluid into the bleed port and its subsequ ent re -compression. Predicted Pitot -pressure distributions are in good agreement with experiment for the case with bleed. Swirl stre ngth probability -density distributions are used to estimate the evolution of turbulence length -sca les throughout the interaction, and the effects of bleed on the amplification of Reynolds stresses are highlighted. Finally, simple improvements to engineerin g-level bleed models are proposed based on the computational results.

Self-Recirculating Casing Treatment for a Radial Compressor

Casing treatment is a widely employed technique to increase the stall margins of turbomachineries. In the last several decades,many researches on casing treatment have been carried out. However,the mechanism of its expanding stall margins is still not very clear. Till now,most casing teatment schemes are designed for axial compressors,while the investigations on casing treatments in centrifugal compressors are rarely reported. Moreover,current investigation methods mainly focus on experiments,and perfect theoretical analysis is not yet feasible. In order to study the effectiveness and further the mechanism of casing treatments in centrifugal compressors,in this paper,a computationally based investigation of the impact of the self-recirculating casing treatment on the performance of a radial compressor is carried out. The results indicate that,by casing bleed and injection,the casing treatment with inclined blades in the cavity expands the stall margin most. At low mass flows,the reversed flow through the cavity with inclined blades develops the counter swirl flow in front of the impeller inlet,which is considered to benefit increasing the pressure rise from the injection port to the bleed port and thereby augment the recirculating flow. At 120% design speed,the stall margin is larger than that at the design speed. However,the cost of extending the stall margin is the reduction of isentropic efficiency. A mended casing treatment by shifting the bleed port upstream is also studied. It is demonstrated that,relative to the original casing treatment,this mend can improve the efficiency evidently notwithstanding a little narrowing of the flow range.

Modelling the bleed port of a thermostatic expansion valve

This article presents a model to predict refrigerant flow rate through the bleed port of a thermostatic expansion valve using a separated flow model. Four types of inlet/outlet conditions: liquid/liquid; liquid/two-phase; two-phase/two-phase; and vapour/vapour are studied. Refrigerant flow rate predictions of the model are compared to measured data. The results of this comparison show that the model is within ±20% for 95% of the experimental data corresponding to either an inlet fluid in a sub-cooled or a two-phase state. When the inlet fluid is in a vapour state, the model is able to predict 96% of the experimental data within ±16%.

ELECTRICALLY CONTROLLED SAMPLER FOR MILK COMPONENT SENSORS

Two prototype samplers were designed and tested to capture a small sample (about 5 mL) during machine milking,so that harvested milk could be automatically analyzed for different components in realtime. To capture a sample, bothsamplers opened a fill port and a bleed port from the long milk tube under vacuum (about 50 kPa) to a sample reservoir,allowing milk to passively drain into the reservoir. Milk was then drawn from the reservoir by closing the valves to the vacuumline and opening the reservoir to the atmosphere. These valves were electrically actuated so that an embedded controller couldoperate the samplers. Due to possible sanitation problems with the first prototype, the second prototype was designed to allowmore effective cleaning. In this prototype, the sample reservoir could be filled with the wash solution during the automatedmilking machine wash cycle. Once filled, filtered air from the atmosphere was ported into the reservoir vacuum, causing thewash fluid to be agitated in the reservoir and ejected back into the long milk tube.

Use of laparoscopic techniques improves outcome from adrenalectomy

Laparoscopic adrenalectomy is a promising alternative to open approaches but safety and efficacy remain unproven. A recent experience with laparoscopic adrenalectomy at the University of Washington was analyzed for efficacy, complications, evolution of technical steps, and clinical outcome. Nineteen adrenalectomies were performed in 16 patients with a mean age of 52 years. Indications included pheochromocytoma (4), functional adenoma (12), and uncontrolled Cushing's disease (3). All patients had computed tomography scans. Meta-iodo-benzyl-guanidine (MIBG) or iodocholesterol scans were done in selected patients. Three patients had bilateral procedures, 7 were on the left and 6 on the right, all via a transperitoneal flank approach. There were no conversions and all procedures were successful. Complications included subcapsular liver hematomas (2), one transfusion, and a bleeding port site requiring repeat laparoscopy. Except for 1 patient with COPD, the mean length of stay was 2.9 days. Laparoscopic adrenalectomy in appropriate patients is safe and effective. For endocrine surgeons with advanced laparoscopic skills, it should be considered a new standard therapy for benign adrenal tumors.

A Simple Telemetry System for Monitoring Chewing Activity of Reindeer

A simple radio-telemetry system for monitoring chewing-biting activity of reindeer (Rangifer t. tarandus) is described. The system is assembled from commercially available components, requiring only minor electronic modifications. The monitored animal should be 530 m from the recording system but is not constrained by cables. The system is completely portable, being independent of mains (110 VAC) power. J. WILDL. MANAGE. 50(4):737-740 In studies of ruminant nutrition and foraging ecology, 1 important problem is to estimate the amount of time and energy spent in grazing and digesting forage. The system described here was designed to monitor chewing activity of reindeer. The investigators wished to know how often an animal engaged in grazing, how much time was spent in cud chewing (ruminating), and how much chewing resulted from each activity (J. Trudell and R. G. White, J. Appl. Ecol. 18:63-81, 1981; and J. Trudell-Moore and R. G. White, Acta Zool. Fenn. 175:47-49, 1983). A simple telemetry system was developed to meet that need. Objectives of the development included: (1) acquisition of chewing information in a quantifiable form, (2) freedom of movement of monitored animal (i.e., no cables tethering animal to a fixed location), (3) simple operation with minimal operator adjustments, and (4) low cost. Support for this project came from the Natl. Sci. Found., Div. Polar Prog., Grant 75-12943RATE and Inst. Arct. Biol. funds. We want to thank J. Trudell-Moore for patience in field testing this system and J. F. Fox for critical review of this manuscript. MATERIALS AND METHODS This telemetry system was assembled from commercially available components, although some of the components required modifications to allow interconnection. A block diagram of the system is shown in Figure 1. In operation, the transducer and bellows-tube assembly encircles the jaw of the animal (Fig. 2). The transmitter clips to either a halter or a saddle and is attached to the transducer by a small cable. The other components are located together at a convenient work spot nearby. Each of the 5 major components, along with necessary modifications, is described below. Additional details of the modifications can be obtained from the 1st author. Transducer.-The transducer consists of a bellows tube (accordion-pleated rubber tubing, t e volume of which changes with length changes) and a pressure sensitive transistor. The bellows tube is plugged at both ends with standard laboratory rubber stoppers and mounted to a harness that is later strapped around the jaw of the animal. The stopper at 1 end is drilled to accept the 1-cm 24-thread transistor housing. This housing is screwed into the hole in the rubber stopper, providing a good seal and a simple mounting. The stopper also is pierced by a small bore (26 gauge) hypodermic needle, used as a static bleed port. This prevents the transducer from recording long-term changes in air pressure (and, indirectly, air temperature), by equalizing internal and external air pressure, while still permitting the rapid pressure changes induced by jaw movements to be recorded. The pressure-sensitive transistor is a PITRAN, Model PTM2M03 (Stow Lab., Hudson, Mass.). (Designation of specific manufacturers and models does not constitute recommendation or endorsement of products.) It has a diaphragm mechanically coupled to the emitterbase junction. Pressure differences across the diaphragm produce large gain changes in the transistor. This model has a linear pressure range of ? 13 Torr. With bias applied to this transistor, pressure changes are transformed to voltage cha ges. The PITRAN is a very high frequency transducer, with typical mechanical resonance about 150 kHz. Bias voltage for this unit is provided by the transmitter (below). Transmitter.-The transmitter is a modified electrocardiogram (EKG) telemetry transmitter (Parks Labs, Beaverton, Oreg.), Model 27-1. It