scholarly journals A comparison between a Coriolis meter and a combination method of a volumetric positive-displacement flowmeter and a densitometer in measuring liquid fuel mass flow at low flow rates

2021 ◽  
Vol 18 ◽  
pp. 100321
Author(s):  
Kar-Hooi Cheong ◽  
Noriyuki Furuichi ◽  
Ryouji Doihara ◽  
Shouta Kamazawa ◽  
Shigenori Kasai ◽  
...  
Keyword(s):  
Mass Flow ◽  
Liquid Fuel ◽  
Combination Method ◽  
Low Flow ◽  
Flow Rates ◽  
Fuel Mass ◽  
Positive Displacement

Large Eddy Simulation of a Bluff-Body–Stabilized Flame With Close-Coupled Liquid Fuel Injection

2013 ◽  
Vol 136 (3) ◽  
Author(s):  
Andrew G. Smith ◽  
Suresh Menon ◽  
Jeffery A. Lovett ◽  
Baris A. Sen
Keyword(s):  
Mass Flow ◽  
Flow Rate ◽  
Liquid Fuel ◽  
Bluff Body ◽  
Fuel Flow Rate ◽  
Flow Rates ◽  
Fuel Mass ◽  
Fuel Flow ◽  
Large Eddy ◽  
Mass Flow Rates

Large eddy simulations (LES) are performed of a bluff-body–stabilized flame with discrete liquid fuel injectors located just upstream of the bluff-body trailing edge in a so-called “close-coupled” configuration. Nonreacting and reacting simulations of the Georgia Tech single flameholder test rig [Cross et al., 2010, “Dynamics of Non-premixed Bluff Body-Stabilized Flames in Heated Air Flow,” Proceedings of ASME Turbo Expo, Paper No. GT2010-23059] are conducted using an Eulerian–Lagrangian approach with a finite volume solver. Experimental data is first used to characterize the boundary conditions under nonreacting conditions before simulating reacting test cases at two different fuel mass flow rates. The two fuel mass flow rates not only result in different global equivalence ratios but different spatial distributions of fuel, especially in the near-field wake of the bluff body. The differing spatial distribution of fuel results in two distinct flame dynamics; at the high-fuel flow rate, large-scale sinusoidal Bérnard/von-Kármán (BVK) oscillations are observed, whereas a symmetric flame is seen under the low-fuel flow rate condition.

Design and Development of a Radial Turbine for Low Flow Turbocharging

2019 ◽  
Author(s):  
Dhinagaran Ramachandran ◽  
Srinivasa Rao Billa ◽  
Balamurugan Mayandi ◽  
Perumal Balappan ◽  
Shyamaprasad Kanthila ◽  
...  
Keyword(s):  
Transient Response ◽  
Mass Flow ◽  
Aerodynamic Performance ◽  
Low Flow ◽  
Angle Distribution ◽  
Turbine Wheel ◽  
Structural Requirements ◽  
Flow Rates ◽  
Mass Flow Rates ◽  
Low Mass

Abstract The scope of this study is to develop a turbocharger turbine wheel with improved aerodynamic performance at low mass flow rates and with reduced inertia for better transient response. The contrasting effect of geometrical shape and size parameters on the objectives of aerodynamic performance and transient response gives rise to the need to explore the design space for the best design having good trade-off between the multi-objective requirements. The search for an optimum aerodynamic design is a challenge due to structural requirements as well. A turbine wheel that is best suited for the current application is selected from the library as a baseline and this wheel is further optimized to meet the targets. Preliminary screening allowed the identification of parameters having major impact on the objectives and these results have been used to train a Response Surface (RS). Further, in the interest of reducing computational cost, a virtual optimization algorithm based on the RS has been employed to predict optimum design within the design constraints. The optimum designs thus obtained are validated with Computational Fluid Dynamics simulations for flow performance and Finite Element solver for satisfying structural requirements. This approach has allowed for application-based design of turbine wheel for instance, by changing key parameters like blade angle distribution, number of blades, axial length, blade height and width. An inertia reduction up to 10% has been obtained while retaining the performance at low mass flow rates.

The Behavior of Liquid Fuel Sprays in Acoustically-Forced Air Swirler Flows

2012 ◽  
Author(s):  
Wookyung Kim ◽  
Shiling Zhang ◽  
Paul Palies ◽  
Jeffrey Cohen ◽  
Scott Liljenberg ◽  
...  
Keyword(s):  
Mass Flow ◽  
Liquid Fuel ◽  
Ambient Pressure ◽  
Stokes Number ◽  
Fuel Spray ◽  
Fuel Mass ◽  
Fuel Droplets ◽  
Air Mixing ◽  
Acoustic Forcing ◽  
Cfd Analyses

The effects of air flow forcing on fuel spray characteristics in a premixing swirler were assessed using ambient-pressure experiments and CFD (LES) analyses. Experimental measurements were performed using phase-locked Phase-Doppler Interferometry on two different swirler/mixer designs. The CFD analyses employed an advanced spray modeling technique to track the surface of the liquid fuel. The swirler designs chosen were representative of advanced low-emissions combustor concepts that emphasize thorough fuel/air mixing for Jet-A fuel. Significant post-processing of the results was performed in order to extract the response of the fuel spray mass flow rate fluctuations and fuel/air ratio to acoustic forcing. The results demonstrated that i) acoustic air forcing did not significantly change the atomization process, but did influence the unsteady transport of fuel droplets within the swirler flow field, ii) the level of fuel mass flow fluctuation was higher for one swirler and the level of fuel/air ratio fluctuations was higher for the other swirler and iii) the different behaviors between the two swirlers are primarily caused by the discrepant alignment of fuel and air distribution and the dissimilar droplet Stokes number which governs the unsteady transport. CFD results were interrogated to help understand the root causes of the observed phenomena. These showed that, for the swirler in which fuel mass flow fluctuations were observed, the swirl number was modulated by the acoustic forcing.

Pressure Losses in Solar Chimney Power Plant

2018 ◽  
Vol 140 (2) ◽  
Author(s):  
Xinping Zhou ◽  
Yangyang Xu
Keyword(s):  
Power Plant ◽  
Mass Flow ◽  
Pressure Loss ◽  
Dynamic Pressure ◽  
Low Flow ◽  
Solar Chimney ◽  
Flow Rates ◽  
Pressure Losses ◽  
Pressure Loss Coefficient ◽  
Solar Chimney Power Plant

This technical brief develops a theoretical model of all the pressure losses in the solar chimney power plant (SCPP, also called solar updraft power plant) and analyzes the pressure losses for different chimney internal stiffening appurtenance (SA) structures, different roof heights, and different collector support parameters. Results show that the exit dynamic pressure drop (EDPD) accounts for the majority of the total pressure loss (TPL), while other losses constitute only small proportions of the TPL, and the collector inlet loss is negligible. Pressure losses are strongly related to the mass flow rate, while reasonable mass flow rates excluding too low flow rates have little influence on the pressure loss ratios (PLRs, defined as the ratios of the pressure losses to the TPL) and the total effective pressure loss coefficient (TEPLC). Designing of the SA structure in view of reducing the drag, for example, using the ring stiffeners without wire spoked instead of the spoked bracing wheels (SBWs), reducing the width of the chimney internal rims of SAs, or reducing the number of SAs results in large reduction of the SA PLR and the TPL. Lower roof leading to higher velocity inside the collector, larger supports, or shorter intersupport distance leads to the increase in the support PLR. This technical brief lays a solid foundation for optimization of SCPPs in future.

Novel Approach to Estimate the Optimum Zone Fuel Mass Flow Rates for a Walking Beam Type Reheating Furnace

2017 ◽  
Vol 39 (7-8) ◽  
pp. 586-597 ◽  
Author(s):  
Chien-Nan Lin ◽  
Yi-Ping Luo ◽  
Jiin-Yuh Jang ◽  
Chao-Hua Wang
Keyword(s):  
Mass Flow ◽  
Flow Rates ◽  
Fuel Mass ◽  
Reheating Furnace ◽  
Novel Approach ◽  
Mass Flow Rates ◽  
Beam Type

scholarly journals Backflow effects on mass flow gain factor in a centrifugal pump

2021 ◽  
Vol 104 (2) ◽  
pp. 003685042199886
Author(s):  
Wenzhe Kang ◽  
Lingjiu Zhou ◽  
Dianhai Liu ◽  
Zhengwei Wang
Keyword(s):  
Centrifugal Pump ◽  
Mass Flow ◽  
Flow Rate ◽  
Low Frequency ◽  
Gain Factor ◽  
Low Flow ◽  
Cavity Volume ◽  
Cavitating Flows ◽  
Inlet Tube ◽  
Low Flow Rate

Previous researches has shown that inlet backflow may occur in a centrifugal pump when running at low-flow-rate conditions and have nonnegligible effects on cavitation behaviors (e.g. mass flow gain factor) and cavitation stability (e.g. cavitation surge). To analyze the influences of backflow in impeller inlet, comparative studies of cavitating flows are carried out for two typical centrifugal pumps. A series of computational fluid dynamics (CFD) simulations were carried out for the cavitating flows in two pumps, based on the RANS (Reynolds-Averaged Naiver-Stokes) solver with the turbulence model of k- ω shear stress transport and homogeneous multiphase model. The cavity volume in Pump A (with less reversed flow in impeller inlet) decreases with the decreasing of flow rate, while the cavity volume in Pump B (with obvious inlet backflow) reach the minimum values at δ = 0.1285 and then increase as the flow rate decreases. For Pump A, the mass flow gain factors are negative and the absolute values increase with the decrease of cavitation number for all calculation conditions. For Pump B, the mass flow gain factors are negative for most conditions but positive for some conditions with low flow rate coefficients and low cavitation numbers, reaching the minimum value at condition of σ = 0.151 for most cases. The development of backflow in impeller inlet is found to be the essential reason for the great differences. For Pump B, the strong shearing between backflow and main flow lead to the cavitation in inlet tube. The cavity volume in the impeller decreases while that in the inlet tube increases with the decreasing of flow rate, which make the total cavity volume reaches the minimum value at δ = 0.1285 and then the mass flow gain factor become positive. Through the transient calculations for cavitating flows in two pumps, low-frequency fluctuations of pressure and flow rate are found in Pump B at some off-designed conditions (e.g. δ = 0.107, σ = 0.195). The relations among inlet pressure, inlet flow rate, cavity volume, and backflow are analyzed in detail to understand the periodic evolution of low-frequency fluctuations. Backflow is found to be the main reason which cause the positive value of mass flow gain factor at low-flow-rate conditions. Through the transient simulations of cavitating flow, backflow is considered as an important aspect closely related to the hydraulic stability of cavitating pumping system.

Assessment of the Use of Humidified Nasal Cannulas for Oxygen Therapy in Patients with Epistaxis

ORL ◽  
2021 ◽  
pp. 1-5
Author(s):  
Jingjing Liu ◽  
Tengfang Chen ◽  
Zhenggang Lv ◽  
Dezhong Wu
Keyword(s):  
Flow Rate ◽  
Oxygen Therapy ◽  
Preliminary Investigation ◽  
Nasal Cannula ◽  
Low Flow ◽  
Antiplatelet Drugs ◽  
Flow Rates ◽  
The Past ◽  
Oxygen Inhalation ◽  
Significant Difference

<b><i>Introduction:</i></b> In China, nasal cannula oxygen therapy is typically humidified. However, it is difficult to decide whether to suspend nasal cannula oxygen inhalation after the nosebleed has temporarily stopped. Therefore, we conducted a preliminary investigation on whether the use of humidified nasal cannulas in our hospital increases the incidence of epistaxis. <b><i>Methods:</i></b> We conducted a survey of 176,058 inpatients in our hospital and other city branches of our hospital over the past 3 years and obtained information concerning their use of humidified nasal cannulas for oxygen inhalation, nonhumidified nasal cannulas, anticoagulant and antiplatelet drugs, and oxygen inhalation flow rates. This information was compared with the data collected at consultation for epistaxis during these 3 years. <b><i>Results:</i></b> No significant difference was found between inpatients with humidified nasal cannulas and those without nasal cannula oxygen therapy in the incidence of consultations due to epistaxis (χ<sup>2</sup> = 1.007, <i>p</i> &#x3e; 0.05). The same trend was observed among hospitalized patients using anticoagulant and antiplatelet drugs (χ<sup>2</sup> = 2.082, <i>p</i> &#x3e; 0.05). Among the patients with an inhaled oxygen flow rate ≥5 L/min, the incidence of ear-nose-throat (ENT) consultations due to epistaxis was 0. No statistically significant difference was found between inpatients with a humidified oxygen inhalation flow rate &#x3c;5 L/min and those without nasal cannula oxygen therapy in the incidence of ENT consultations due to epistaxis (χ<sup>2</sup> = 0.838, <i>p</i> &#x3e; 0.05). A statistically significant difference was observed in the incidence of ENT consultations due to epistaxis between the low-flow nonhumidified nasal cannula and nonnasal cannula oxygen inhalation groups (χ<sup>2</sup> = 18.428, <i>p</i> &#x3c; 0.001). The same trend was observed between the 2 groups of low-flow humidified and low-flow nonhumidified nasal cannula oxygen inhalation (χ<sup>2</sup> = 26.194, <i>p</i> &#x3c; 0.001). <b><i>Discussion/Conclusion:</i></b> Neither high-flow humidified nasal cannula oxygen inhalation nor low-flow humidified nasal cannula oxygen inhalation will increase the incidence of recurrent or serious epistaxis complications; the same trend was observed for patients who use anticoagulant and antiplatelet drugs. Humidification during low-flow nasal cannula oxygen inhalation can prevent severe and repeated epistaxis to a certain extent.

scholarly journals Net-exergetic, hydraulic and thermal optimization of coaxial heat exchangers using fixed flow conditions instead of fixed flow rates

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Tobias Blanke ◽  
Markus Hagenkamp ◽  
Bernd Döring ◽  
Joachim Göttsche ◽  
Vitali Reger ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Laminar Flow ◽  
Mass Flow ◽  
Flow Rate ◽  
Heat Exchangers ◽  
Circular Ring ◽  
Flow Conditions ◽  
Flow Rates ◽  
Mass Flow Rates ◽  
Pipe Radius

AbstractPrevious studies optimized the dimensions of coaxial heat exchangers using constant mass flow rates as a boundary condition. They show a thermal optimal circular ring width of nearly zero. Hydraulically optimal is an inner to outer pipe radius ratio of 0.65 for turbulent and 0.68 for laminar flow types. In contrast, in this study, flow conditions in the circular ring are kept constant (a set of fixed Reynolds numbers) during optimization. This approach ensures fixed flow conditions and prevents inappropriately high or low mass flow rates. The optimization is carried out for three objectives: Maximum energy gain, minimum hydraulic effort and eventually optimum net-exergy balance. The optimization changes the inner pipe radius and mass flow rate but not the Reynolds number of the circular ring. The thermal calculations base on Hellström’s borehole resistance and the hydraulic optimization on individually calculated linear loss of head coefficients. Increasing the inner pipe radius results in decreased hydraulic losses in the inner pipe but increased losses in the circular ring. The net-exergy difference is a key performance indicator and combines thermal and hydraulic calculations. It is the difference between thermal exergy flux and hydraulic effort. The Reynolds number in the circular ring is instead of the mass flow rate constant during all optimizations. The result from a thermal perspective is an optimal width of the circular ring of nearly zero. The hydraulically optimal inner pipe radius is 54% of the outer pipe radius for laminar flow and 60% for turbulent flow scenarios. Net-exergetic optimization shows a predominant influence of hydraulic losses, especially for small temperature gains. The exact result depends on the earth’s thermal properties and the flow type. Conclusively, coaxial geothermal probes’ design should focus on the hydraulic optimum and take the thermal optimum as a secondary criterion due to the dominating hydraulics.

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