scholarly journals The Effect of Geometrical, Operational, Mixing Methods, and Rheological Parameters on Discharge Coefficients of Internal-Mixing Twin-Fluid Atomizers

Processes ◽  
2020 ◽  
Vol 8 (5) ◽  
pp. 563
Author(s):  
Farid A. Hammad ◽  
Kai Sun ◽  
Jan Jedelsky ◽  
Tianyou Wang
Keyword(s):  
Discharge Coefficient ◽  
Cold Test ◽  
Rheological Parameters ◽  
Discharge Coefficients ◽  
Control Factors ◽  
Air Core ◽  
Internal Mixing ◽  
Wide Range ◽  
Inside Out ◽  
Liquid Ring

Accurate prediction of the discharge coefficient (CD) for internal-mixing twin-fluid (IMTF) atomizers is challenging, the effect of control factors remains inadequately understood, and comparative data on the CD of IMTF atomizers are unavailable. This work presents an experimental study on CD for different IMTF atomizers with a wide range of factors, including the gas-to-liquid ratio (GLR), the inlet-overpressure ratio (∆pmix/pamb), the orifice length-to-diameter ratio (Lo/do), and the liquid viscosity (µL). Five atomizers with different internal-mixing principles were probed on a cold test rig, including the frequently studied outside-in-gas (OIG) and inside-out-gas (IOG) effervescent types, the recently-introduced outside-in-liquid (OIL) and air-core-liquid-ring (ACLR) atomizers, and our new design named the swirling-air-core-liquid-ring (SACLR) atomizer. The results demonstrate that CD is governed mainly by GLR, and reduces if GLR, Lo/do, or µL is increased. An increase in ∆pmix/pamb causes a CD reduction up to ∆pmix/pamb = 0.98, and CD increases for a higher ∆pmix/pamb. Surprisingly, differences in CD amid examined atomizers were found negligible, although the flow visualization inside the orifice showed a significantly different flow character for each one of the atomizers. Finally, a general CD correlation fitting with an R2 ≥0.99 for all the tested nozzles was proposed. The results amend the present knowledge, allow design optimization, and provide flow rate prediction for a variety of IMTF atomizers.

scholarly journals Numerical Research of Flows into Gullies with Different Outlet Locations

Water ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 794 ◽  
Author(s):  
Rita F. Carvalho ◽  
Pedro Lopes ◽  
Jorge Leandro ◽  
Luis M. David
Keyword(s):  
Surface Runoff ◽  
Discharge Coefficient ◽  
Drainage System ◽  
Flow Conditions ◽  
Hydraulic Behavior ◽  
Discharge Coefficients ◽  
Wide Range ◽  
Flow Features ◽  
Numerical Research ◽  
Estimation Of Uncertainty

Gullies are sewer inlets placed in pavements usually covered by bar grates. They are the most common linking-element used to drain a wide range of flows from surface runoff into the buried drainage system. Their hydraulic behavior and their overall hydraulic performance is dependent on the flow conditions, the gully dimension, geometry, and location of the outlet device. Herein a numerical research based on Volume Of Fluid ( V O F ) to detect the interface, and on the Shear Stress Transport S S T k - ω turbulence model was conducted to study the importance of the outlet location and characterize flows through them in drainage conditions. Results provided detailed information about flow features, discharge coefficients, and efficiencies for different outlet locations. The authors identified three different regimes, R 1 , R 2 , and R 3 , and concluded that the outlet location influences the velocity field along the gully, the discharge coefficient, and the drainage efficiency. This allows for the estimation of uncertainty and its variation for different outlet positions.

Discharge Coefficients of Rotating Short Orifices With Radiused and Chamfered Inlets

2004 ◽  
Vol 126 (4) ◽  
pp. 803-808 ◽  
Author(s):  
M. Dittmann ◽  
K. Dullenkopf ◽  
S. Wittig
Keyword(s):  
Discharge Coefficient ◽  
Pressure Ratio ◽  
Reynolds Numbers ◽  
Frame Of Reference ◽  
Efficient Operation ◽  
Discharge Coefficients ◽  
Wide Range ◽  
Secondary Air ◽  
Cooling Air ◽  
Actual Geometry

The secondary air system of modern gas turbine engines consists of numerous stationary or rotating passages to transport the cooling air, taken from the compressor, to thermally high loaded components that need cooling. Thereby the cooling air has to be metered by orifices to control the mass flow rate. Especially the discharge behavior of rotating holes may vary in a wide range depending on the actual geometry and the operating point. The exact knowledge of the discharge coefficients of these orifices is essential during the design process in order to guarantee a well adapted distribution of the cooling air inside the engine. This is crucial not only for a safe and efficient operation but also fundamental to predict the component’s life and reliability. In this paper two different methods to correlate discharge coefficients of rotating orifices are described and compared, both in the stationary and rotating frame of reference. The benefits of defining the discharge coefficient in the relative frame of reference will be pointed out. Measurements were conducted for two different length-to-diameter ratios of the orifices with varying inlet geometries. The pressure ratio across the rotor was varied for rotational Reynolds numbers up to ReΦ=8.6×105. The results demonstrate the strong influence of rotation on the discharge coefficient. An analysis of the complete data shows significant optimizing capabilities depending on the orifice geometry.

Steady Compressible Flow through a Single Row of Radial Holes in the Wall of a Pipeline

1970 ◽  
Vol 12 (4) ◽  
pp. 248-258 ◽  
Author(s):  
G. H. Trengrouse
Keyword(s):  
Discharge Coefficient ◽  
Pressure Change ◽  
Single Row ◽  
One Dimensional ◽  
Discharge Coefficients ◽  
Wide Range ◽  
Theoretical Predictions ◽  
Flow Through ◽  
Flow Theories ◽  
Good Agreement

Measured values of discharge coefficient for air flow through a single row of radial holes in the wall of a pipeline are reported, together with the values of pipe Mach numbers in the immediate vicinity of the holes. A wide range of pressure and area ratios are considered, the flow through the holes being either into or out of the pipe. It is shown that the effects on the measured values of both the pressure level at discharge from the holes and the air temperature are negligible. The agreement between the pressure change in the pipeline due to the holes, obtained experimentally, and that predicted by simple, one-dimensional flow theories is generally unsatisfactory. However, theoretical predictions of the jet efflux angles based on two-dimensional, incompressible, non-viscous flow arguments are in good agreement with those measured, but discrepancies do arise in the prediction of discharge coefficients.

Discharge Coefficients of Rotating Short Orifices With Radiused and Chamfered Inlets

2003 ◽  
Author(s):  
M. Dittmann ◽  
K. Dullenkopf ◽  
S. Wittig
Keyword(s):  
Discharge Coefficient ◽  
Pressure Ratio ◽  
Reynolds Numbers ◽  
Frame Of Reference ◽  
Efficient Operation ◽  
Discharge Coefficients ◽  
Wide Range ◽  
Secondary Air ◽  
Cooling Air ◽  
Actual Geometry

The secondary air system of modern gas turbine engines consists of numerous stationary or rotating passages to transport the cooling air, taken from the compressor, to thermally high loaded components that need cooling. Thereby the cooling air has to be metered by orifices to control the mass flow rate. Especially the discharge behavior of rotating holes may vary in a wide range depending on the actual geometry and the operating point. The exact knowledge of the discharge coefficients of these orifices is essential during the design process in order to guarantee a well adapted distribution of the cooling air inside the engine. This is crucial not only for a safe and efficient operation but also fundamental to predict the component’s life and reliability. In this paper two different methods to correlate discharge coefficients of rotating orifices are described and compared, both in the stationary and rotating frame of reference. The benefits of defining the discharge coefficient in the relative frame of reference will be pointed out. Measurements were conducted for two different length-to-diameter ratios of the orifices with varying inlet geometries. The pressure ratio across the rotor was varied for rotational Reynolds numbers up to Reφ = 8:6 × 105. The results demonstrate the strong influence of rotation on the discharge coefficient. An analysis of the complete data shows significant optimising capabilities depending on the orifice geometry.

scholarly journals Discharge Coefficient Measurements of Film-Cooling Holes With Expanded Exits

1997 ◽  
Author(s):  
M. Gritsch ◽  
A. Schulz ◽  
S. Wittig
Keyword(s):  
Mach Number ◽  
Film Cooling ◽  
Discharge Coefficient ◽  
Pressure Ratio ◽  
Cylindrical Hole ◽  
Flow Conditions ◽  
Discharge Coefficients ◽  
Wide Range ◽  
Cooling Hole ◽  
Film Cooling Holes

This paper presents the discharge coefficients of three film-cooling hole geometries tested over a wide range of flow conditions. The hole geometries include a cylindrical hole and two holes with a diffuser shaped exit portion (i.e. a fanshaped and a laidback fanshaped hole). The flow conditions considered were the crossflow Mach number at the hole entrance side (up to 0.6), the crossflow Mach number at the hole exit side (up to 1.2), and the pressure ratio across the hole (up to 2). The results show that the discharge coefficient for all geometries tested strongly depends on the flow conditions (crossflows at hole inlet and exit, and pressure ratio). The discharge coefficient of both expanded holes was found to be higher than of the cylindrical hole, particularly at low pressure ratios and with a hole entrance side crossflow applied. The effect of the additional layback on the discharge coefficient is negligible.

Effect of Crossflows on the Discharge Coefficient of Film Cooling Holes With Varying Angles of Inclination and Orientation

2001 ◽  
Author(s):  
Michael Gritsch ◽  
Achmed Schulz ◽  
Sigmar Wittig
Keyword(s):  
Inclination Angle ◽  
Film Cooling ◽  
Discharge Coefficient ◽  
Orientation Angle ◽  
Discharge Coefficients ◽  
Wide Range ◽  
Cooling Hole ◽  
Discharge Behavior ◽  
Hole Geometry ◽  
Film Cooling Holes

Measurements of discharge coefficients for five configurations of cylindrical film cooling hole geometries are presented. These comprise holes of varying angles of inclination (α= 30, 45, and 90deg) and orientation (γ= 0, 45, and 90deg) which are tested over a wide range of engine like conditions in terms of internal and external crossflow Mach numbers (Mam=0…1.2, Mac=0…0.6) as well as pressure ratios (ptc/pm=1…2.25). Results show that discharge coefficients do not solely depend on hole geometry but are also profoundly affected by the internal and external crossflow conditions. The effect of increasing the orientation angle on the discharge behavior is very similar to the effect of increasing the inclination angle. Both result in higher losses particularly at the cooling hole inlet while the losses at the hole exit are only slightly affected.

Further Experiments and Investigations for Discharge Coefficient of PTC 6 Flow Nozzle in a Wide Range of Reynolds Number

2015 ◽  
Vol 138 (4) ◽  
Author(s):  
Noriyuki Furuichi ◽  
Yoshiya Terao ◽  
Shinichi Nakao ◽  
Keiji Fujita ◽  
Kazuo Shibuya
Keyword(s):  
Reynolds Number ◽  
Turbulent Flow ◽  
Power Plants ◽  
Discharge Coefficient ◽  
High Accuracy ◽  
Steam Turbines ◽  
Number Range ◽  
Accurate Evaluation ◽  
Discharge Coefficients ◽  
Wide Range

The discharge coefficients of the flow nozzles based on ASME PTC 6 are measured in a wide range of Reynolds number from Red = 5.8 × 104 to Red = 1.4 × 107, and the equations of the discharge coefficients are developed for the laminar, the transitional, and the turbulent flow ranges. The equation of the discharge coefficient consists of a nominal discharge coefficient and the tap effect. The nominal discharge coefficient is the discharge coefficient without tap, which is experimentally determined from the discharge coefficients measured for different tap diameters. The tap effects are correctly obtained by subtracting the nominal discharge coefficient from the discharge coefficient measured. The deviation of the present experimental results from the equations developed is from −0.06% to 0.04% for 3.0 × 106 < Red < 1.4 × 107 and from −0.11% to 0.16% for overall Reynolds number range examined. The developed equations are expected to be capable of estimating the discharge coefficient of the throat tap nozzle defined in PTC 6 with a high accuracy and contribute for the high accurate evaluation of steam turbines in power plants.

Effect of Crossflows on the Discharge Coefficient of Film Cooling Holes With Varying Angles of Inclination and Orientation

2001 ◽  
Vol 123 (4) ◽  
pp. 781-787 ◽  
Author(s):  
Michael Gritsch ◽  
Achmed Schulz ◽  
Sigmar Wittig
Keyword(s):  
Inclination Angle ◽  
Film Cooling ◽  
Discharge Coefficient ◽  
Orientation Angle ◽  
Discharge Coefficients ◽  
Wide Range ◽  
Cooling Hole ◽  
Discharge Behavior ◽  
Hole Geometry ◽  
Film Cooling Holes

Measurements of discharge coefficients for five configurations of cylindrical film cooling hole geometries are presented. These comprise holes of varying angles of inclination (α=30, 45, and 90 deg) and orientation (γ=0, 45, and 90 deg), which are tested over a wide range of engine-like conditions in terms of internal and external crossflow Mach numbers (Mam=0…1.2,Mac=0…0.6) as well as pressure ratios ptc/pm=1…2.25. Results show that discharge coefficients do not depend solely on hole geometry, but are also profoundly affected by the internal and external crossflow conditions. The effect of increasing the orientation angle on the discharge behavior is very similar to the effect of increasing the inclination angle. Both result in higher losses, particularly at the cooling hole inlet while the losses at the hole exit are only slightly affected.

The Leakage Thru Straight and Slant Labyrinths and Honeycomb Seals

1975 ◽  
Vol 97 (4) ◽  
pp. 495-501 ◽  
Author(s):  
C. A. Meyer ◽  
J. A. Lowrie
Keyword(s):  
Discharge Coefficient ◽  
Pressure Ratio ◽  
Test Results ◽  
Labyrinth Seals ◽  
Previous Theory ◽  
Discharge Coefficients ◽  
Wide Range ◽  
Honeycomb Seals

Leakage tests have been run over a wide range of pressure ratios and clearances for several types of seals. The results of tests of labyrinth seals show some important differences compared to previous theory. The discharge coefficient of a single seal has been found to jump from 0.62 to 0.78 when a second seal is added downstream. This effect depends on the clearance, pitch, and the pressure ratio across the seal. This phenomena has not been considered in past theories which assumed fixed seal discharge coefficients independent of the seal position and its pressure ratio in the Labyrinth. The test results are presented in a form which is easier to use than those based on the more complicated previous theory.

scholarly journals Rhythm and rate control of atrial fibrillation in the emergency department – A large community-based observational study

CJEM ◽  
2017 ◽  
Vol 20 (6) ◽  
pp. 834-840 ◽  
Author(s):  
Cameron J. Gilbert ◽  
Paul Angaran ◽  
Zana Mariano ◽  
Theresa Aves ◽  
Paul Dorian
Keyword(s):  
Atrial Fibrillation ◽  
Emergency Department ◽  
Rate Control ◽  
Primary Diagnosis ◽  
Left Ventricular ◽  
Rhythm Control ◽  
Chads2 Score ◽  
Control Factors ◽  
Wide Range ◽  
Canadian City

AbstractObjectiveAtrial fibrillation (AF) is the most common arrhythmia presentation to the emergency department (ED) and frequently results in admission to the hospital. Although rarely life-threatening and not usually an emergent condition, AF places a large burden on our health-care system. The objective of this study was to describe the practices of ED physicians in the management of AF in a large urban Canadian city.MethodsFrom January 1, 2010 to December 31, 2010, patients with a primary diagnosis of AF were identified across 10 EDs in Toronto, Canada (N=2,609). Fifty patients were selected at random from each hospital for a detailed chart review (n=500).ResultsTwo hundred thirty-two patients (46%) received rate control, and 129 (26%) received rhythm control with the remainder (28%) receiving neither therapy. Sixty-seven percent of patients were discharged home. Most patients (79%) were symptomatic on arrival; however, only a minority of these (31%) received rhythm control. Factors that were associated with rhythm control included younger age, duration of palpitations ≤ 48 hours, a lower CHADS2 score, and the absence of left ventricular dysfunction.ConclusionOur data suggest a wide range of practice amongst ED physicians treating patients presenting to the ED with a primary diagnosis of AF. A randomized trial is needed to better understand the optimal management strategy in this patient population and setting.

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