scholarly journals Research on Flow Characteristics of Straight Line Conjugate Internal Meshing Gear Pump

Processes ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 269
Author(s):  
Hongqiang Chai ◽  
Guolai Yang ◽  
Guoguo Wu ◽  
Guixiang Bai ◽  
Wenqi Li
Keyword(s):  
Flow Rate ◽  
Gear Pump ◽  
Flow Pulsation ◽  
Average Flow Rate ◽  
Geometric Flow ◽  
Average Flow ◽  
Pulsation Rate ◽  
Straight Line ◽  
Internal Meshing ◽  
Simulated Flow

The improvement of the overall performance of hydraulic pumps is the basis of intelligent hydraulics. Taking the straight line conjugate internal meshing gear pump as the research object, the theoretical flow rate and the geometric flow pulsation rate equations are established in this study through the volume change method. The change laws of the gear pair’s geometric parameters on the theoretical flow rate and the geometric flow pulsation rate are studied. The simulation model of the internal flow channel is established, and the influence factors and the influence degree of the flow pulsation and average flow rate are analyzed. The high-pressure positive displacement pump test system is also designed and built. The performance evaluations are conducted, and the experimental results are analyzed. The results show that the periodic change of the meshing point position is the root cause of the geometric flow pulsation. The theoretical flow rate and the geometric flow pulsation rate are 103.71 L/min and 1.76%, respectively. To increase the theoretical flow rate whilst decreasing the geometric flow pulsation rate, the tip circle radius of the external gear should be increased as much as possible within the allowable range of the design calculation. Amongst the three influencing factors that produce flow pulsation, the oil compressibility has no effect on the flow pulsation. The uneven internal leakage is the main factor, and the geometric flow pulsation only accounts for a small proportion. The internal leakage reduces the simulated flow rate by 3.59 L/min. The difference between the experimental and simulated flow rates is less than 2%. Within the allowable speed range, the rotation speed of the external gear should be increased as much as possible to increase the average flow rate and the volumetric efficiency.

A Design Method for Thermosyphon Solar Domestic Hot Water Systems

1987 ◽  
Vol 109 (2) ◽  
pp. 150-155 ◽  
Author(s):  
M. P. Malkin ◽  
S. A. Klein ◽  
J. A. Duffie ◽  
A. B. Copsey
Keyword(s):  
Flow Rate ◽  
Design Method ◽  
Water Systems ◽  
Hot Water ◽  
Average Flow Rate ◽  
Domestic Hot Water ◽  
Average Flow ◽  
Solar Fraction ◽  
Wide Range ◽  
Flow Circuit

A modification to the f-Chart method has been developed to predict monthly and annual performance of thermosyphon solar domestic hot water systems. Stratification in the storage tank is accounted for through use of a modified collector loss coefficient. The varying flow rate throughout the day and year in a thermosyphon system is accounted for through use of a fixed monthly “equivalent average” flow rate. The “equivalent average” flow rate is that which balances the thermosyphon buoyancy driving force with the frictional losses in the flow circuit on a monthly average basis. Comparison between the annual solar fraction predited by the modified design method and TRNSYS simulations for a wide range of thermosyphon systems shows an RMS error of 2.6 percent.

Modification of lymph during passage through the lymph node: effect of histamine

1983 ◽  
Vol 245 (4) ◽  
pp. H553-H559
Author(s):  
M. B. Maron
Keyword(s):  
Lymph Node ◽  
Flow Rate ◽  
Evans Blue ◽  
Protein Concentration ◽  
Lymph Flow ◽  
Blue Dye ◽  
Base Line ◽  
Average Flow Rate ◽  
Significant Modification ◽  
Average Flow

The possibility that histamine may cause the fluid and protein content of lymph to be altered during passage through the lymph node was evaluated using the canine perfused popliteal lymph node preparation. This preparation enables nodal perfusion via an afferent lymphatic (all other afferents are ligated) with artificial lymph of known composition and collection of the total efferent effluent for analysis of potential changes in volume and composition. In 11 dogs, the node was perfused at an average flow rate of 0.229 ml/min with artificial lymph containing 3.71 g/100 ml albumin. Under base-line conditions, there was no significant modification of the lymph as it passed through the node. The addition of histamine to the infusate (2-4 micrograms base/ml) caused the efferent lymph flow to increase to 0.295 ml/min (35.3% increases, P less than 0.05), the efferent protein concentration to increase to 4.32 g/100 ml (15.2% increases, P less than 0.05), and the efferent protein flux to increase from 8.40 to 12.86 mg/min (58.0% increases, P less than 0.05). The appearance of Evans blue dye-tagged protein and plasma protein fractions, not originally present in the lymph, in the efferent lymph at this time further indicated that the source of the added fluid and protein was the nodal vasculature. Mass balance calculations indicated that the addition of a fluid with a protein concentration of approximately 90% that of plasma to the lymph could account for the observed increases in efferent lymph flow and protein concentration.(ABSTRACT TRUNCATED AT 250 WORDS)

A preliminary investigation of the freshwater red algae in streams of southern Ontario, Canada

1980 ◽  
Vol 58 (11) ◽  
pp. 1295-1318 ◽  
Author(s):  
Robert G. Sheath ◽  
Beverly J. Hymes
Keyword(s):  
Flow Rate ◽  
Red Algae ◽  
Preliminary Investigation ◽  
Average Flow Rate ◽  
Southern Ontario ◽  
Average Flow ◽  
Cell Organization ◽  
Conductivity Range ◽  
Freshwater Red Algae ◽  
The Relationship

Ten taxa of freshwater red algae have been observed in a survey of 62 streams and rivers within southern Ontario, Canada, over a period of 3 years. Five species are additions to the flora of Canada, Chroodactylon ramosum, Boldia erythrosiphon, Sirodotia tenuissima, Batrachospermum densum, and B. ectocarpum. In addition to these algae, Audouinella violacea, Sirodotia suecia, and Tuomeya fluviatilis are new observations within Ontario.Most of the Ontario red algae are restricted to streams or rivers with a minimum average flow rate of 10 m min−1. Audouinella violacea, B. moniliforme, and Lemanea fucina occur in a large number of streams which have a wide pH and conductivity range whereas S. tenuissima and B. ectocarpum are confined to one of the sites examined.Ultrastructural findings are reported concerning the cell organization of Boldia as well as the relationship between Batrachospermum plants and the "chantransia" stage. A key to the 10 taxa is included plus descriptions and a list of epiphytes of each alga are presented.

Dynamic Response of a Centrifugal Blower to Periodic Flow Fluctuations

1986 ◽  
Vol 108 (1) ◽  
pp. 77-82 ◽  
Author(s):  
A. N. Abdel-Hamid
Keyword(s):  
Flow Rate ◽  
Static Pressure ◽  
Pressure Rise ◽  
Rotation Frequency ◽  
Periodic Flow ◽  
Average Flow Rate ◽  
Centrifugal Blower ◽  
Inertia Effects ◽  
Average Flow ◽  
Discharge Flow Rate

Experimental investigation of the dynamic response of a centrifugal blower to periodic flow rate modulations was carried out at different blower operating conditions. For modulation frequencies in the range of 0.0085–0.085 of the shaft rotation frequency, the fluctuating pressures at inlet, discharge, and across a flow orifice were simultaneously measured and analyzed in the time and frequency domains. Measurements of the amplitude and phase of the transfer function between the blower static pressure rise and the discharge flow rate fluctuations indicated that the quasi-steady approximation should be limited to frequencies lower than 0.02 of the shaft rotation frequency. For the same average flow rate, the static pressure rise progressively lagged the discharge flow rate fluctuations as the frequency was increased. The trend was similar to that of the inertia effects of a fluctuating flow in a pipe. For the same frequency these inertia effects increased as the average flow rate through the blower was decreased. Applications of the results to on-line measurements of the slope of the characteristic curve and improved dynamic modeling of centrifugal compressors and blowers are discussed.

Left atrial conduit volume is generated by deviation from the constant-volume state of the left heart: a combined MRI-echocardiographic study

2004 ◽  
Vol 286 (6) ◽  
pp. H2416-H2424 ◽  
Author(s):  
Andrew W. Bowman ◽  
Sándor J. Kovács
Keyword(s):  
Flow Rate ◽  
Left Atrial ◽  
Left Ventricular ◽  
Constant Volume ◽  
Left Heart ◽  
Filling Rate ◽  
Average Flow Rate ◽  
Average Flow ◽  
Volume State ◽  
The Relationship

Although modeling the four-chambered heart as a constant-volume pump successfully predicts causal physiological relationships between cardiac indexes previously deemed unrelated, the real four-chambered heart slightly deviates from the constant-volume state by ventricular end systole. This deviation has consequences that affect chamber function, specifically, left atrial (LA) function. LA attributes have been characterized as booster pump, reservoir, and conduit functions, yet characterization of their temporal occurrence or their causal relationship to global heart function has been lacking. We investigated LA function in the context of the constant-volume attribute of the left heart in 10 normal subjects using cardiac magnetic resonance imaging (MRI) and contemporaneous Doppler echocardiography synchronized via ECG. Left ventricular (LV) and LA volumes as a function of time were determined via MRI. Transmitral flow, pulmonary vein (PV) flow, and lateral mitral annular velocity were recorded via echocardiography. The relationship between the MRI-determined diastolic LA conduit-volume (LACV) filling rate and systolic LA filling rate correlate well with the relationship between the echocardiographically determined average flow rate during the early portion of the PV D wave and the average flow rate during the PV S wave ( r = 0.76). We conclude that the end-systolic deviation from constant volume for the left heart requires the generation of the LACV during diastole. Because early rapid filling of the left ventricle is the driving force for LACV generation while the left atrium remains passive, it may be more appropriate to consider LACV to be a property of ventricular diastolic rather than atrial function.

scholarly journals Parameter sensitivity analysis of a lumped-parameter model of a chain of lymphangions in series

2013 ◽  
Vol 305 (12) ◽  
pp. H1709-H1717 ◽  
Author(s):  
Samira Jamalian ◽  
Christopher D. Bertram ◽  
William J. Richardson ◽  
James E. Moore
Keyword(s):  
Sensitivity Analysis ◽  
Flow Rate ◽  
Pressure Difference ◽  
Lymphatic System ◽  
Lumped Parameter Model ◽  
Average Flow Rate ◽  
Average Flow ◽  
Lumped Parameter ◽  
Time Average ◽  
A Chain

Any disruption of the lymphatic system due to trauma or injury can lead to edema. There is no effective cure for lymphedema, partly because predictive knowledge of lymphatic system reactions to interventions is lacking. A well-developed model of the system could greatly improve our understanding of its function. Lymphangions, defined as the vessel segment between two valves, are the individual pumping units. Based on our previous lumped-parameter model of a chain of lymphangions, this study aimed to identify the parameters that affect the system output the most using a sensitivity analysis. The system was highly sensitive to minimum valve resistance, such that variations in this parameter caused an order-of-magnitude change in time-average flow rate for certain values of imposed pressure difference. Average flow rate doubled when contraction frequency was increased within its physiological range. Optimum lymphangion length was found to be some 13–14.5 diameters. A peak of time-average flow rate occurred when transmural pressure was such that the pressure-diameter loop for active contractions was centered near maximum passive vessel compliance. Increasing the number of lymphangions in the chain improved the pumping in the presence of larger adverse pressure differences. For a given pressure difference, the optimal number of lymphangions increased with the total vessel length. These results indicate that further experiments to estimate valve resistance more accurately are necessary. The existence of an optimal value of transmural pressure may provide additional guidelines for increasing pumping in areas affected by edema.

Rock Remover Design for an Amadas Combine1

2003 ◽  
Vol 30 (2) ◽  
pp. 88-91
Author(s):  
P. D. Blankenship
Keyword(s):  
Flow Rate ◽  
Consumer Acceptance ◽  
Duct System ◽  
Average Flow Rate ◽  
Conveyor System ◽  
Preliminary Testing ◽  
Average Flow ◽  
System A ◽  
Foreign Materials ◽  
Rock Weight

Abstract Peanuts are harvested with various amounts and types of foreign materials that must be removed during post-harvest processing for consumer acceptance of peanut products. To assist in rock removal during harvest, a modification to the pneumatic conveyor system used to transport peanuts from underneath a standard Amadas combine to the holding bin was designed. The design utilizes air flow patterns and cavitations following an elbow in the duct system and consists of a properly sized and spaced opening in one component of the conveyor system. A stationary pneumatic conveyor system with a controllable peanut delivery apparatus was utilized in developing the duct modification. After preliminary testing during development, the efficiency of the duct modification rock removal was evaluated with three lots of peanuts averaging 0.45 t containing an average 371 rocks (3.2% of sample mass). Peanuts were conveyed through the duct system at an average flow rate of 3.9 t/hr. An average of 30 rocks comprising 42.5% of the total rock weight was extracted from the peanuts. The weight of rocks removed averaged 153.5 g and ranged from 18.7 to 320.7 g. Rocks not removed averaged 24.2 g and ranged from 1.7 to 202.8 g. Results from the tests indicate that the design of the duct modification appears to be effective in removing larger rocks from peanuts but not effective in removing smaller rocks.

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