Analytical Study of Wind Influence on In-Flight Sprinkler Droplets

An analytical model to describe the dynamics of in-flight droplets is presented in this paper to augment information on wind influence on travel distance of in-flight sprinkler droplets. The model is ballistic-theory based. It employs a relatively simple, wide-range empirical relationship between drag coefficient and Reynolds' number to replace the several sets of relations for a specified range of Reynolds numbers. The fourth-order Runge-Kutta numerical integration techniques were used to solve the trajectory equations. A modified exponential model for droplet size distribution was used during the simulation. Comparative analysis showed that agreement exists between the predictions of this model and that of earlier models. Droplets with a diameter smaller than 0.1 mm travelled farthest. Within the droplet range of 0.5 mm to 4.5 mm, as droplet diameter increased, travelled distance increased with increasing wind speed. The extent of drift increased sharply within the droplet range of 0.5 mm to 0.05 mm and increased mildly for droplet diameters greater than 0.5 mm. The model also attempts to identify droplets that are likely to contribute to drift loss and those that have a high probability of contributing only to distortion of the distribution pattern

Antiseismic response research of horizontal residual heat removal pump in different seismic spectrum input directions

A million kilowatt horizontal residual heat removal pump is an essential part of the first loop residual heat removal system in nuclear power plants; it is the second most significant piece of nuclear power equipment. The residual heat removal pump of a nuclear power plant is examined by using a multiseismic spectrum, multiinput direction method to analyze its dynamic characteristics and responses. The aim of this analysis was to determine the seismic responses and possible actions to reduce damage to the integral structure. The favorable and unfavorable spectra are investigated as well. The research focuses on avoiding the damaging effects caused by earthquakes. The maximum value of seismic effect and the corresponding seismic input direction are determined, laying a speculative foundation for structural design and installation. Utilizing a response spectrum method, the antiseismic performance of a pump at SSE seismic load has been analyzed according to an algorithm using the square root of the sum of the squares. The result shows that the deformation of the impeller surface fitted with a wear ring decreases along the direction of flow in different input directions of the seismic spectrum. The largest deformation occurs at an angle of approximately 135 degrees; thus, antiseismic analysis should be conducted at this input angle to conservatively evaluate the antiseismic performance, and the installation angle designed for frequent earthquakes should avoid 135 degrees to decrease the deformation caused by the seismic force. Calculation results prove that the clearance between the rotor and the stator of the horizontal residual heat removal pump shows satisfactory seismic response performance that fulfills the requirements for antiseismic design according to the RCC-M standard; this may reduce seismic damage and avoid environmental disasters

Investigation on the influence of jetting equipment on the characteristics of centrifugal pump

To reduce radial noises from the motor of centrifugal pumps, this study designed a water cooling system called jettingequipment to replace traditional fan cooling systems in pump motors. By measuring radiated noises, head, efficiency, andcavitation performance, the research compared the differences among experimental results of the original pump unit,the one with a normal design jetting pipe and another one with a larger jetting pipe. Results show that the radiatedsound pressure level of the model pump was significantly reduced by 8.3 dB after integrating the jetting pipe. With a nor-mal jetting pipe, no significant changes were observed in the head, efficiency, and shaft power curves, and cavitation per-formance improved under small flow rate. However, the performance with the larger jetting pipe worsened, except thehump phenomenon of the model pump under a small flow rate was enhanced. Computational fluid dynamics methodwas used to calculate the internal flow of three model pumps in order to investigate the jetting flow effect. A compari-son among the flow fields at the inlet of the three types of pumps indicated that high-pressure water injection can effec-tively control inlet recirculation and improve velocity distribution in the inlet flow field with decreased recirculationvortex strength and recirculation onset critical flow rate

Performance Improvement of a Micro Impulse Water Turbine Based on Orthogonal Array

The study on structural design and efficiency improvement of the micro impulse water turbine with the super-low specific speed has rarely been reported in literature. In this paper, a micro impulse water turbine was optimized on the base of the orthogonal array of L18(37) with six factors. The range analysis and variance analysis were conducted to present the significance ranking of factors and the optimal combinations of factors, aiming to improve the water turbine efficiency taken as the experimental indicator in the orthogonal experiment. And then the optimal parameter combination for the water turbine was calculated by orthogonal experiment. Moreover, the internal flow field and hydraulic performance were simulated numerically to investigate the principle of performance improvement by comparing the optimized water turbine with the original. Also, the numerical method was verified by experimental result from performance tests of the original water turbine. As a result, the runner torque of the optimized water turbine was 13% higher than that of the original and the water turbine efficiency was improved by 5.8 percentage points at the rated operating condition

Seismic response research of a residual heat removal pump at startup considering the fluid-induced vibration

Residual heat removal pumps used in nuclear power plants are activated by an emergency or accident such as an earthquake. Their antiseismic performance is therefore a critical factor. In this study, we used a new method based on computational fluid dynamics and finite element analysis to investigate the seismic response of a residual heat removal pump under a 1/2 SSE seismic load. The fluid-induced vibration was also considered in the simulation to ensure accurate prediction of the antiseismic performance. The deformation of the trailing edge of the impeller at startup was quantitatively analyzed by examining the seismic response and fluid-induced vibration. The expression for the clearance between the impeller and diffuser at startup was obtained by combining the effects of the seismic load and fluid-induced vibration. An analysis of the results showed that the deformation of the trailing edge of the impeller produced a greater safety margin in the pump structure when it is subjected to a seismic load. The fluid-induced vibration had greater effect on seismic response analysis at startup. The expression of the clearance between the impeller and diffuser at startup was obtained as a damped oscillation function that combines an exponential function and a sine function

Antiseismic response research of horizontal residual heat removal pump in different seismic spectrum input directions

A million kilowatt horizontal residual heat removal pump is an essential part of the first loop residual heat removal system in nuclear power plants; it is the second most significant piece of nuclear power equipment. The residual heat removal pump of a nuclear power plant is examined by using a multiseismic spectrum, multiinput direction method to analyze its dynamic characteristics and responses. The aim of this analysis was to determine the seismic responses and possible actions to reduce damage to the integral structure. The favorable and unfavorable spectra are investigated as well. The research focuses on avoiding the damaging effects caused by earthquakes. The maximum value of seismic effect and the corresponding seismic input direction are determined, laying a speculative foundation for structural design and installation. Utilizing a response spectrum method, the antiseismic performance of a pump at SSE seismic load has been analyzed according to an algorithm using the square root of the sum of the squares. The result shows that the deformation of the impeller surface fitted with a wear ring decreases along the direction of flow in different input directions of the seismic spectrum. The largest deformation occurs at an angle of approximately 135 degrees; thus, antiseismic analysis should be conducted at this input angle to conservatively evaluate the antiseismic performance, and the installation angle designed for frequent earthquakes should avoid 135 degrees to decrease the deformation caused by the seismic force. Calculation results prove that the clearance between the rotor and the stator of the horizontal residual heat removal pump shows satisfactory seismic response performance that fulfills the requirements for antiseismic design according to the RCC-M standard; this may reduce seismic damage and avoid environmental disasters

Antiseismic response research of horizontal residual heat removal pump in different seismic spectrum input directions

A million kilowatt horizontal residual heat removal pump is an essential part of the first loop residual heat removal system in nuclear power plants; it is the second most significant piece of nuclear power equipment. The residual heat removal pump of a nuclear power plant is examined by using a multiseismic spectrum, multiinput direction method to analyze its dynamic characteristics and responses. The aim of this analysis was to determine the seismic responses and possible actions to reduce damage to the integral structure. The favorable and unfavorable spectra are investigated as well. The research focuses on avoiding the damaging effects caused by earthquakes. The maximum value of seismic effect and the corresponding seismic input direction are determined, laying a speculative foundation for structural design and installation. Utilizing a response spectrum method, the antiseismic performance of a pump at SSE seismic load has been analyzed according to an algorithm using the square root of the sum of the squares. The result shows that the deformation of the impeller surface fitted with a wear ring decreases along the direction of flow in different input directions of the seismic spectrum. The largest deformation occurs at an angle of approximately 135 degrees; thus, antiseismic analysis should be conducted at this input angle to conservatively evaluate the antiseismic performance, and the installation angle designed for frequent earthquakes should avoid 135 degrees to decrease the deformation caused by the seismic force. Calculation results prove that the clearance between the rotor and the stator of the horizontal residual heat removal pump shows satisfactory seismic response performance that fulfills the requirements for antiseismic design according to the RCC-M standard; this may reduce seismic damage and avoid environmental disasters

Review of intelligent sprinkler irrigation technologies for remote autonomous system

Changing of environmental conditions and shortage of water demands a system that can manage irrigation efficiently. Autonomous irrigation systems are developed to optimize water use for agricultural crops. In dry areas or in case of inadequate rainfall, irrigation becomes difficult. So, it needs to be automated for proper yield and handled remotely for farmer safety. The aim of this study is to review the needs of soil moisture sensors in irrigation, sensor technology and their applications in irrigation scheduling and, discussing prospects. The review further discusses the literature of sensors remotely communicating with self-propelled sprinkler irrigation systems, distributed wireless sensor networks, sensors and integrated data management schemes and autonomous sprinkler control options. On board and field-distributed sensors can collect data necessary for real-time irrigation management decisions and transmit the information directly or through wireless networks to the main control panel or base computer. Communication systems such as cell phones, satellite radios, and internet-based systems are also available allowing the operator to query the main control panel or base computer from any location at any time. Selection of the communication system for remote access depends on local and regional topography and cost. Traditional irrigation systems may provide unnecessary irrigation to one part of a field while leading to a lack of irrigation in other parts. New sensors or remotely sensing capabilities are required to collect real time data for crop growth status and other parameters pertaining to weather, crop and soil to support intelligent and efficient irrigation management systems for agricultural processes. Further development of wireless sensor applications in agriculture is also necessary for increasing efficiency, productivity and profitability of farming operations

Experimental Investigations on the Inner Flow Behavior of Centrifugal Pumps under Inlet Air-Water Two-Phase Conditions

Centrifugal pumps are widely used and are known to be sensitive to inlet air-water two-phase flow conditions. The pump performance degradation mainly depends on the changes in the two-phase flow behavior inside the pump. In the present paper, experimental overall pump performance tests were performed for two different rotational speeds and several inlet air void fractions (αi) up to pump shut-off condition. Visualizations were also performed on the flow patterns of a whole impeller passage and the volute tongue area to physically understand pump performance degradation. The results showed that liquid flow modification does not follow head modification as described by affinity laws, which are only valid for homogeneous bubbly flow regimes. Three-dimensional effects were more pronounced when inlet void fraction increased up to 3%. Bubbly flow with low mean velocities were observed close to the volute tongue for all αi, and returned back to the impeller blade passages. The starting point of pump break down was related to a strong inward reverse flow that occurred in the vicinity of the shroud gap between the impeller and volute tongue area

Structural design and performance characteristics of the fluidic sprinkler application technology for saving irrigation water: a review

The fluidic sprinkler was designed to have the prospect of a simple design, ease of construction, low energy consumption, and water saving. The present review focused on the fluidic sprinkler, compared the performance parameters of the fluidic sprinkler with the impact sprinkler, and highlighted the main challenges associated with the fluidic sprinkler. Even though the fluidic sprinkler compares quite well with the impact sprinkler, the review highlighted that the fluidic sprinkler appears to have more variability in application rate (0-1.5 mm/h) than the impact sprinkler (0-0.8 mm/h). The wetted radii were, on average, less than the impact sprinkler by 9.7, 9.3, 11.0, and 9.9% at 200, 250, 300, and 350 kPa operating pressures, respectively. Experiments on the fluidic sprinkler have mainly concentrated on the structural design of the fluidic component, water distribution profile, coefficient of uniformity, droplet size characterisation, and rotation uniformity, as well as the effect of different nozzle sizes on hydraulic performance under varying discharge and pressure conditions ranging from 100-500 kPa under indoor conditions. However, experimental studies on its performance in the field remain scanty. Statistical analysis of research papers published on the fluidic sprinkler indicates that less than 10% of the studies focused on the performance of the fluidic sprinkler on the field, and more than 90% on the design, structural and hydraulic performance under indoor conditions. Rotation stability of the fluidic sprinkler and testing with different sizes of the nozzle under low-pressure conditions on the field require further research to achieve energy and water saving through optimisation of the operating conditions