Experimental Analysis of Simplex Atomizer Spray and Swirling Flow Interactions in Unconfined Conditions

2015 ◽  
Author(s):  
Muthu Selvan ◽  
Muralidhara Suryanarayana Rao ◽  
Indu Kharb ◽  
Sundararajan Thirumalachari ◽  
Vinod Kumar Vyas ◽  
...  
Keyword(s):  
Size Distribution ◽  
Water Flow ◽  
Droplet Size ◽  
Flow Rate ◽  
Swirling Flow ◽  
Air Flow ◽  
Single Mode ◽  
Air Flow Rate ◽  
Volume Percentage ◽  
Flow Rates

An experimental study has been conducted to investigate the interaction between the conical spray produced by simplex atomizer and the swirling flow from an axial swirler. This work has been carried out in an unconfined ambience at isothermal conditions, using water. Malvern spray analyzer with a three dimensional traverse is used to characterize the swirling flow and spray interactions at various axial and radial locations. Images of spray at different conditions of air and water mass flow rates have been analyzed. Increasing the air mass flow through swirler at constant water flow rate, changes the spray structure significantly. These structural changes are sudden and highly dependent on the initial conditions of the spray. At smaller air flow rates, single-mode droplet size distribution at mid-plane changes into a bi-modal distribution at an air flow rate of about 35 kg/hr, with higher contribution of larger droplets. With further increase in air flow rate (90, 110 and 130 kg/hr), the bi-modal size distribution is maintained but with a larger volumetric fraction of small droplets. At different axial distances, the droplet size distributions are similar (single mode and bimodal distributions depending on air flow rate). But volume percentage of larger droplets is less compared to those of smaller droplets, at larger axial distance. At outer radial locations of the spray, volume percentage of larger droplets reduces and that of smaller droplets increases significantly, due to secondary droplet breakup. The interaction between the swirl and spray causes droplets to move radially outwards, resulting in droplet break-up by impact on the dome. Cases with higher air to water flow ratios exhibit significant changes in drop size distribution due to such swirl-spray interactions.

scholarly journals Experimental Study on Thermal Radiation Attenuation Using Water Mist of Twin-fluid Atomizer

2021 ◽  
Vol 35 (4) ◽  
pp. 24-32
Author(s):  
Jae Geun Jo ◽  
Chi Young Lee
Keyword(s):  
Thermal Radiation ◽  
Water Flow ◽  
Flow Rate ◽  
Air Flow ◽  
Water Flow Rate ◽  
Water Mist ◽  
Air Flow Rate ◽  
Radiation Attenuation ◽  
Rate Condition ◽  
Flow Rates

In this study, the thermal radiation attenuation performance of water mist was investigated using twin-fluid atomizers. The water and air flow rates of Small atomizer were 36~105 g/min and 10~30 L/min, whereas those of Large atomizer were 37~300 g/min and 20~60 L/min, respectively. In the present experimental range, the thermal radiation attenuation of Small atomizer and Large atomizer were 6.1~11.9% and 5.2~14.6%, respectively. With the increase in water and air flow rates, the thermal radiation attenuation increased, and under similar water and air flow rate conditions, Small atomizer showed higher thermal radiation attenuation than Large atomizer. Based on the present experimental data, it was found that the air (gas) discharge area is a potentially important factor in determining the thermal radiation attenuation performance. Additionally, through the analysis of thermal radiation attenuation per unit water flow rate, it was confirmed that the twin-fluid atomizer can result in higher thermal radiation attenuation than the single-fluid atomizer under the same water flow rate condition.

Velocity Characteristics of a Confined Highly-Turbulent Swirling Flow Near a Swirl Plate (Data Bank Contribution)

1994 ◽  
Vol 116 (4) ◽  
pp. 685-693 ◽  
Author(s):  
R. X. Shi ◽  
B. Chehroudi
Keyword(s):  
Flow Rate ◽  
Recirculation Zone ◽  
Swirling Flow ◽  
Air Flow ◽  
Tangential Velocity ◽  
Velocity Profiles ◽  
Air Flow Rate ◽  
Reversed Flow ◽  
Swirl Number ◽  
Flow Rates

Axial and tangential components of the velocity vector are measured using a Laser Doppler Velocimeter (LDV) system in a confined highly turbulent isothermal swirling flow near a swirl plate. The flow has essential features of swirl-stabilized flame combustors. Throughout this study, a constant “nominal” swirl number of 0.36 is generated by air jets from a set of slots in a swirl plate. A low-speed coflowing air, referred to as dilution air, is uniformly distributed around the swirling flow by use of an annular-shaped honeycomb. Three different swirling air flow rates with a fixed dilution flow rate are studied and results are discussed. Detailed mean axial and tangential velocity profiles at several axial locations show that the size and the strength of the central recirculation zone are strongly dependent on the swirling air flow rate. Increasing the swirl air flow rate increases both the radial extent and the axial length of the central recirculation zone. Mean total and reversed air flow rates are calculated by integrating the mean axial velocity profiles. In the setup used in this study and up to the axial positions investigated, the reversed flow rate as a percent of the total flow rate seems to be linearly proportional to the reversed-flow zone area, being independent of the swirl air flow rate at a fixed nominal swirl number value. As swirl air flow rate is increased, the root mean square (rms) of the axial and tangential velocity fluctuations increase monotonically at almost all radial positions except sufficiently away from the swirl plate and near the chamber axis. Several velocity biasing correction methods are reviewed. A simple velocity biasing correction scheme is applied in this study to investigate its effect on the conclusions reached in the study.

scholarly journals Geometrical Optimization of a Venturi-Type Microbubble Generator Using CFD Simulation and Experimental Measurements

Designs ◽  
2021 ◽  
Vol 5 (1) ◽  
pp. 4
Author(s):  
Dillon Alexander Wilson ◽  
Kul Pun ◽  
Poo Balan Ganesan ◽  
Faik Hamad
Keyword(s):  
Water Flow ◽  
Flow Rate ◽  
Cfd Simulation ◽  
Air Flow ◽  
Bubble Diameter ◽  
Diameter Ratio ◽  
Experimental Measurements ◽  
Cfd Model ◽  
Flow Rates ◽  
Throat Diameter

Microbubble generators are of considerable importance to a range of scientific fields from use in aquaculture and engineering to medical applications. This is due to the fact the amount of sea life in the water is proportional to the amount of oxygen in it. In this paper, experimental measurements and computational Fluid Dynamics (CFD) simulation are performed for three water flow rates and three with three different air flow rates. The experimental data presented in the paper are used to validate the CFD model. Then, the CFD model is used to study the effect of diverging angle and throat length/throat diameter ratio on the size of the microbubble produced by the Venturi-type microbubble generator. The experimental results showed that increasing water flow rate and reducing the air flow rate produces smaller microbubbles. The prediction from the CFD results indicated that throat length/throat diameter ratio and diffuser divergent angle have a small effect on bubble diameter distribution and average bubble diameter for the range of the throat water velocities used in this study.

Model-Based Analysis of Transient Behavior of Large Scale CFB Boilers

2003 ◽  
Author(s):  
Ari Kettunen ◽  
Timo Hyppa¨nen ◽  
Ari-Pekka Kirkinen ◽  
Esa Maikkola
Keyword(s):  
Flow Rate ◽  
Large Scale ◽  
Air Flow ◽  
Model Parameters ◽  
Air Flow Rate ◽  
Process Data ◽  
Cfb Boiler ◽  
Flow Rates ◽  
Load Change ◽  
Secondary Air

The main objective of this study was to investigate the load change capability and effect of the individual control variables, such as fuel, primary air and secondary air flow rates, on the dynamics of large-scale CFB boilers. The dynamics of the CFB process were examined by dynamic process tests and by simulation studies. A multi-faceted set of transient process tests were performed at a commercial 235 MWe CFB unit. Fuel reactivity and interaction between gas flow rates, solid concentration profiles and heat transfer were studied by step changes of the following controllable variables: fuel feed rate, primary air flow rate, secondary air flow rate and primary to secondary air flow ratio. Load change performance was tested using two different types of tests: open and closed loop load changes. A tailored dynamic simulator for the CFB boiler was built and fine-tuned by determining the model parameters and by validating the models of each process component against measured process data of the transient test program. The know-how about the boiler dynamics obtained from the model analysis and the developed CFB simulator were utilized in designing the control systems of three new 262 MWe CFB units, which are now under construction. Further, the simulator was applied for the control system development and transient analysis of the supercritical OTU CFB boiler.

scholarly journals Experimental Investigation on Improvement of Wet Cooling Tower Efficiency with Diverse Packing Compaction Using ANN-PSO Algorithm

Energies ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 167
Author(s):  
Hasan Alimoradi ◽  
Madjid Soltani ◽  
Pooriya Shahali ◽  
Farshad Moradi Kashkooli ◽  
Razieh Larizadeh ◽  
...  
Keyword(s):  
Neural Network ◽  
Water Temperature ◽  
Water Flow ◽  
Flow Rate ◽  
Cooling Tower ◽  
Air Flow ◽  
Water Flow Rate ◽  
Pso Algorithm ◽  
Outlet Temperature ◽  
Air Flow Rate

In this study, a numerical and empirical scheme for increasing cooling tower performance is developed by combining the particle swarm optimization (PSO) algorithm with a neural network and considering the packing’s compaction as an effective factor for higher accuracies. An experimental setup is used to analyze the effects of packing compaction on the performance. The neural network is optimized by the PSO algorithm in order to predict the precise temperature difference, efficiency, and outlet temperature, which are functions of air flow rate, water flow rate, inlet water temperature, inlet air temperature, inlet air relative humidity, and packing compaction. The effects of water flow rate, air flow rate, inlet water temperature, and packing compaction on the performance are examined. A new empirical model for the cooling tower performance and efficiency is also developed. Finally, the optimized performance conditions of the cooling tower are obtained by the presented correlations. The results reveal that cooling tower efficiency is increased by increasing the air flow rate, water flow rate, and packing compaction.

scholarly journals A twin-fluid injector for FCC feed injection

2019 ◽  
Vol 4 (3) ◽  
pp. 109-115
Author(s):  
Deepak Kumar ◽  
Tushar Sikroria ◽  
Kushari A ◽  
Pramod Kumar ◽  
Sriganesh G
Keyword(s):  
Droplet Size ◽  
Flow Rate ◽  
Liquid Flow ◽  
Liquid Flow Rate ◽  
Air Flow ◽  
Product Yield ◽  
Droplet Velocity ◽  
Injection System ◽  
Airflow Rate ◽  
Air Flow Rate

In Fluidized Bed Catalytic Cracking (FCC) process, hydrocarbon feed undergoes vapour phase cracking in presence of hot regenerated catalyst to produce valuable products like LPG, Gasoline and Diesel. FCC feed injection system is most critical hardware component of FCC unit in order to get desired product yield by minimizing the undesirable dry gas and coke yield. Typically, twin-fluid nozzles (hydrocarbon and stream) are used to atomize the feed. In the present study, a twin-fluid injector, with an internal impactor to minimize the droplet size and velocity, is designed, developed and characterized. The performance of the feeding injector was evaluated using water and air as operating fluids and the droplet size and velocity were measured 150 mm downstream of the injector tip using a PDPA system for different water and air flow rates. The average droplet size (D32) showed an increase while the droplet velocity remained almost constant with the increase in the liquid flow rate for a given flow rate of air, consistent with the increase in droplet size with decreasing air-liquid ratio for twin–fluid atomizers. But, for a given liquid flow rate, the droplet SMD decreased and the droplet velocity increased with increasing airflow rate, which can be attributed to the increase in overall kinetic energy due to the increase in air flow rate. The flow rate of liquid was seen to be independent of air flow rate unlike conventional twin-fluid atomizers. The droplet size was found to be a function of ALR and the local volume flux of the droplets was found to be a function of the liquid flow rate.

Coordinated control of fuel flow rate and air flow rate of a supersonic heat-airflow simulated test system

2020 ◽  
Vol 124 (1278) ◽  
pp. 1170-1189
Author(s):  
C. Cai ◽  
L. Guo ◽  
J. Liu
Keyword(s):  
Flow Rate ◽  
Control Algorithm ◽  
Air Flow ◽  
Coordinated Control ◽  
Test System ◽  
Gas Temperature ◽  
Air Flow Rate ◽  
Flow Rates ◽  
Fuel Flow ◽  
Simulated Test

ABSTRACTThe gas temperature of the supersonic heat airflow simulated test system is mainly determined by the fuel and air flow rates which enter the system combustor. In order to realise a high-quality control of gas temperature, in addition to maintaining the optimum ratio of fuel and air flow rates, the dynamic characteristics of them in the combustion process are also required to be synchronised. Aiming at the coordinated control problem of fuel and air flow rates, the mathematical models of fuel and air supply subsystems are established, and the characteristics of the systems are analysed. According to the characteristics of the systems and the requirements of coordinated control, a fuzzy-PI cross-coupling coordinated control strategy based on neural sliding mode predictive control is proposed. On this basis, the proposed control algorithm is simulated and experimentally studied. The results show that the proposed control algorithm has good control performance. It cannot only realise the accurate control of fuel flow rate and air flow rate, but also realise the coordinated control of the two.

Water Flow Distribution in Horizontal Protruding-Type Header Contaminated With Bubbles

1999 ◽  
Author(s):  
Sachiyo Horiki ◽  
Masahiro Osakabe
Keyword(s):  
Uniform Distribution ◽  
Gas Phase ◽  
Water Flow ◽  
Flow Rate ◽  
Water Distribution ◽  
Air Flow ◽  
Water Flow Rate ◽  
Flow Distribution ◽  
Air Flow Rate ◽  
Distribution Behavior

Abstract Flow header for small multiple pipes is commonly used in boilers and heat exchangers. The system contributes to raise the heat transfer efficiency in the components. The flow distribution mechanism of the header for water has been studied and the calculation procedure for the design has been recommended for a single-phase condition. It is also recommended to avoid the bubbles in the header to obtain a uniform water flow rate to each small pipe. But in some cases, the header has to be used to distribute a flow containing bubbles. Distribution behavior of water with a gas-phase was studied experimentally in a horizontal header with four vertical pipes. In the present experimental header, it was possible to protrude the branch pipes inside of the header and the effect of protruding length on the water distribution behavior was studied. When the protruding length was 0, the water distribution rate to the first pipe rapidly increased and the rates to the others decreased with a small amount of bubbles. As the bubbles in the header were absorbed only into the first pipe, the average two-phase density in the first pipe decreased. The decreased pressure head promotes the rush of water into the first pipe such as in an airlift pump. By increasing the air flow rate in the header inlet further, the flow rate to the first pipe took a maximum and then tended to decrease. The increased air flow rate in the first pipe increased the pressure loss in the pipe and resulted in a reduction in the water flow rate. The more important and serious behavior could be seen in the other pipes where the water flow rate decreased to 1/5 of the uniform distribution rate. By increasing the protruding length, the non-uniform distribution of water was suppressed because the gas-phase entered not only the first pipe but also the others. The best result was obtained when the four branch pipes were protruded into the center of header.

scholarly journals Investigations of hydraulic operating conditions of air lift pump with three types of air-water mixers

2015 ◽  
Vol 47 (1) ◽  
pp. 69-85 ◽  
Author(s):  
Marek Kalenik
Keyword(s):  
Water Flow ◽  
Flow Rate ◽  
Air Flow ◽  
Operating Conditions ◽  
Water Delivery ◽  
Air Flow Rate ◽  
Analysis Of Results ◽  
Delivery Pipe ◽  
Air Lift

Abstract: Investigations of hydraulic operating conditions of air lift pump with three types of air-water mixers. The paper presents the analysis of results of the investigations concerning the influence of various constructive solutions of the air-water mixers on hydraulic operating conditions of the air lift pump. The scope of the investigations encompassed the determination of characteristics of delivery head and delivery rate for three types of air-water mixers applied in the constructed air lift pump. Using the obtained results, the efficiency of the three types of air-water mixers applied in this air lift pump was determined. The analysis was carried out and there was checked whether the improved analytical Stenning-Martin model can be used to design air lift pumps with the air-water mixers of these types. The highest capacity in the water transport was reached by the air lift pump with the 1st type air-water mixer, the lowest one – with the 3rd type air-water mixer. The water flow in the air lift pump increases along with the rise in the air flow. The lower are the hydraulic losses generated during flow of the air flux by the air-water mixer, the higher is the air lift pump capacity. Along with the rise in the water delivery head, the capacity of the air lift pump decreases. The highest efficiency is reached by the air lift pump with the 1st type air-water mixer, the lowest – with the 3st type air-water mixer. The efficiency of the air lift pump for the three investigated types of air-water mixers decreases along with the rise in air flow rate and water delivery head. The values of submergence ratio (h/L) of the delivery pipe, calculated with the use of the improved analytical Stenning-Martin model, coincide quite well with the values of h/L determined from the measurements.

Development of Air/Water Two-Phase Flow Centrifugal Pump and Its Operating Characteristics

2003 ◽  
Author(s):  
Akinori Furukawa ◽  
Satoshi Ohshita ◽  
Kusuo Okuma ◽  
Satoshi Watanabe
Keyword(s):  
Water Flow ◽  
Flow Rate ◽  
Two Phase Flow ◽  
Air Flow ◽  
Water Flow Rate ◽  
Phase Flow ◽  
Air Flow Rate ◽  
Operating Characteristics ◽  
Two Phase ◽  
Flow Pump

A centrifugal impeller, the pumping action of which could be highly kept even at an air-water two-phase flow condition of inlet void fraction more than 30% in the region of relatively high water flow rate, has been developed. In the present paper, the design concept of two-phase flow impeller is described, at first, with experimental results. The short bladed forward impeller with high outlet blade angle was decided to keep theoretical head higher even in two-phase flow condition and to disperse the air accumulating region on the suction blade surface by the water jet flow coming from the pressure side. Furthermore, the tandem arrangement of outer and inner rotating cascades with the same blade numbers was adopted to suppress the rotating stall phenomena appearing in the case of a single stage of outer cascade. It should be noted that these results were obtained with operating a boost pump installed upstream of mixing section of air and water, that is not an actual operation of two-phase flow pump. Secondly, the operating characteristics of this two-phase flow pump with change of air flow rate were investigated experimentally without operating the boost pump. As the trajectory of operating point with increasing air flow rate appears along the resistance curve of piping system, the impossibility of pumping occurs at lower air flow rate even though pump head takes a positive value at high air flow rate with increasing water flow rate. It is recognized that it is necessary to improve two-phase flow head characteristic curves in the region of low water flow rate to operate in wider two-phase flow conditions.

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