Drop Inlet Research Articles

Study on spray characteristics of a compact pressure swirl nozzle integrating tangential inlet flow channel and swirl chamber

Pressure swirl nozzles are widely applied in various heat and mass transfer applications due to advantages of reliable performance, simple structure, and easy processing. However, the complex design of the nozzle structure makes it difficult to miniaturize the pressure swirl nozzle, which restricts its use in limited spaces. In this study, a compact pressure swirl nozzle is proposed by merging a swirl chamber with the tangential inlet flow channel, addressing the issue of liquid atomization in limited spaces. The key geometric parameters are determined based on the internal flow properties by swirl chamber simulation. A spray test bench utilizing a phase Doppler particle analyzer and a high-speed camera was built to study the effect of pressure drop, geometric size, and nozzle inlet shape on spray characteristics. The simulation results show that the nozzle diameter and inlet shape are the main factors affecting flow in the swirl chamber. The experimental results further demonstrate that increasing nozzle diameter increases flow rate and spray cone angle, causing the droplets to move to the spray edge. The spray characteristics are affected by the inlet shape of the nozzle hole: radial velocity and particle size show a wider range of change with a funnel-shaped inlet. Axial velocity and pressure drop are obviously affected by a cylindrical-shaped inlet. This study provided a new design approach for pressure swirl nozzles and achieved flow rate of 5–35 l/h and Sauter mean diameter below 40 μm with an overall weight of 12 g. This compact nozzle construction is a reference for the design of atomizing nozzles in limited spaces.

Emission characteristics and performance of SCR coated on DPF with different soot loads

Selective catalytic reduction (SCR) catalyst coated on diesel particulate filters (DPF), term as SDPF, become a popular subject of current research due to the capability of improving the NOx conversion efficiency and catalytic activity under low-temperature and low-load conditions. This study investigated the impact of SDPF emission characteristics and performance with different soot loads. The results showed that, soot load had little effect on engine fuel consumption. With the increase in soot load, the pressure drop and SDPF inlet temperature showed an upward trend, and the NOx conversion efficiency decreased sharply. NOx conversion efficiency was the result of competition between exhaust temperature and NO2 concentration. When the soot load was 9.97 g/L, SDPF lost the ability to reduce NOx emission. SDPF could reduce nucleation-mode particle number (PN) emission by 2–3 orders of magnitude, the filtration efficiency of nucleation-mode PN emission was the competition result between physical collection mechanism and chemical reaction. The particle diameter of particles with passive regeneration reaction with NO2 ranges from 10.8 to 45.3 nm. SDPF could reduce the accumulation-mode PN emission by 1–2 orders of magnitude, and the filtration efficiency of accumulation-mode PN emission was greatly affected by the physical collection mechanism. Increasing the soot load of SDPF could effectively reduce the nucleation-mode PN emission, but had no obvious effect on the accumulation-mode. At low engine speed, the filtration efficiency of nucleation-mode and accumulation-mode PN increased significantly with the increase in the SDPF soot loads. The maximum filtration efficiencies of nucleation-mode, accumulation-mode, and total PN were 99.93 %, 99.36 %, and 99.56 %, respectively. With the increase in soot load, the geometric mean diameter of SDPF-out increased.

Culvert Inspection Vehicle with Improved Telemetry Range

Proper inspection of small culverts can prevent roadway failures, traffic disturbances, and save tens of thousands of dollars on costly repairs. The Vermont Agency of Transportation (VTrans) has adopted a policy that requires all culverts to be inspected every 5 years. Because of this, approximately 9,600 small culverts must be inspected annually. In this study, a lightweight inspection vehicle was designed, built, and tested to meet VTrans requirements for efficient and affordable small culvert inspection. Optimal parameters for video transmission through small culverts were understood through theory and a series of field tests. Vehicle form factor was chosen for maneuverability through small, flooded culverts. Performance for drop inlet inspection scenarios is characterized and discussed. Compared with prior designs, the “Hydraulic Inspection Vehicle Explorer (HIVE) 2.0” inspection vehicle offered much greater video telemetry range and superior maneuverability.

Effects of the bottom slope and guiding wall length on the performance of a vortex drop inlet.

Laboratory experiments were conducted to assess the performance of a vortex drop inlet with a spiral intake in subcritical and supercritical flow conditions. The water surface elevation at multiple locations was measured for different flowrates by varying the extent of the guiding wall and the longitudinal and radial bottom slopes. The measurements show that a steeper longitudinal bottom slope decreases the water surface elevation at the beginning of the intake, resulting in a transcritical flow in the intake structure. However, a steeper longitudinal bottom slope also causes the maximum water surface elevation to occur within the spiral intake. For an effective vortex drop inlet design, achieving a low water surface elevation throughout the entire spiral intake structure is required. Experimental results show that the two seemingly conflicting design criteria, namely, achieving a low water surface elevation in the approach channel and reducing the maximum water surface elevation in the intake structure, can be simultaneously achieved by adding a radial bottom slope.

Evaluation of Soil Saver Walls on Aquatic Organism Passage Through Box Culverts

Abstract Reinforced concrete box culverts are designed to provide hydraulic conveyance at peak stream discharge in a cost-effective manner; however, these structures can promote headcutting. Many state departments of transportation construct soil saver walls or similar structures on the upstream of box culverts to prevent headcutting. These walls act as a drop inlet and may hinder free movement of aquatic organisms. The potential impact on aquatic organism passage has resulted in regulatory pressure to develop alternatives or modifications to the traditional soil saver wall design. This article contains the results of an analysis of the potential impact of box culverts with solid soil saver walls on aquatic organism passage. The results of a survey of thirty states and fifteen field sites on the current state-of-practice for box culverts, and flume tests using model box culverts with a solid soil saver wall and with modified design to promote aquatic passage are presented. Modifications to the soil saver wall design are recommended based on the results of the survey of states, field surveys, and flume testing.

A computer model for designing of permanent gully control structures

Engineering measures of soil and water conservation are an integral part of watershed management or development, and thus they must be designed accurately and economically. Designing of various gully control structures plays a vital role in the success of any watershed development programme. Analytical designing of these structures in terms of hydrologic, hydraulic and structural stability is very important. The study aims at developing comprehensive module for software namely SCS_Designer model for designing of different permanent gully control structures (drop spillway, drop inlet spillway and chute spillway) and other structures along with testing and validation of the developed module of the model. SCS_Designer model also has the provision to check the step-wise procedure followed by the model for the designing of various structures. These help the users especially students to analyze the differences in design parameters by changing the input data. Also these saved step-wise procedure files make SCS_Designer an effective teaching tool. SCS_Designer was tested with the help of standard examples for different permanent gully control structures. The design results obtained using the SCS_Designer were compared with the corresponding design results from different sources and error analysis was performed. In most cases, the design results obtained using the model matched exactly with the respective design results given in the source. Small deviation in design parameters was due to truncation and round off errors. Thus, it was concluded that SCS_Designer is validated and can be used as a standard designing tool for different permanent gully control structures viz drop spillway, drop inlet spillway and chute spillway. Furthermore, it can be used as an effective teaching tool. Key words: Gully control, structures, validation, computer model.

The core pressure drop characteristics in a CANDU 6 reactor

The core pressure drop characteristics in a CANDU 6 have been examined to reveal the mechanism inducing the difference in the core pressure drop among four passages. The general characteristics for the inlet header temperature and core pressure drop are deduced from the measured data of CANDU 6 NPPs. The passages, which are connected to the purification system, are shown to have a larger core pressure drop and lower inlet header temperature compared with other passages in a loop. The temperature difference among four inlet headers has been analytically obtained by considering the effect of the purification system and verified by the measured data of CANDU 6 NPPs. The relationship between the inlet header temperature and core pressure drop has been secured from the magnetite transport mechanism in a CANDU 6. The analytical computations for a CANDU 6 NPP have revealed that the core pressure drop difference among four passages is largely dependent on the single phase friction factor rather than the mass flow rate in a passage. The calculated single phase friction factors are in accord with the magnetite deposition characteristics derived from the difference in the inlet header temperature.

Ecological engineering in a new town development: Drainage design in The Woodlands, Texas

This paper presents a comparative study of two different drainage designs in a 10,930-ha new town development of The Woodlands, Texas. Open surface drainage by shallow grassed swales was used in the first two subdivisions that were developed with ecological approaches. Open surface drainage mimics the natural flow regime and is regarded to mitigate development impacts on watershed. In other later subdivisions, the drainage design shifted back to a conventional stormwater drainage system, that is, curb and gutter, drop inlet, and underground piping, known to concentrate stormwater and lead to downstream flooding. The objective of this study is to compare The Woodlands’ two drainage systems on their correlation with downstream floods. Two sub-watersheds within The Woodlands that used different drainage designs were compared. U.S. Geological Survey stream data from the gauge station at the outlet of each sub-watershed were used for analysis. Geographic Information System was used to quantify the development conditions. Correlation analysis was performed using measured precipitation and streamflow data. Results show that open drainage watershed generated less storm runoff than the conventional drainage watershed, given the similar impervious area in both watersheds. Furthermore, the open surface drainage watershed responded to rainfall in a way similar to its predevelopment natural forest conditions, indicating effective flood mitigation post development. In contrast, in the conventional drainage watershed, the precipitation–streamflow correlations increased enormously after development. The open drainage system presents an advantage over the conventional drainage one in mitigating flood problems in urban development.

Modelling for Simplifying Hydraulic Design Procedure of Drop Inlet Spillway

Models were developed to determine the hydraulic design dimension of drop inlet structure. The kinetic energy and drop of flowing water were taken as independent variables. The kinetic energy was estimated from the design discharges and drops of the structures made by Department of Soil Conservation, Government of Uttar Pradesh. Coetlicient of determination (R2) of estimate of the models was 0.9907 and 0.9998 respectively for diameter and length of drop inlet pipe. The predicated (model) values were in close agreement with standard design values. The models estimated hydraulic design values within ± 7 and 3% accuracy level for diameter and length of drop inlet pipe, respectively. The Students t-test between standard procedure and models values indicated that model estimate were at par with standard values at 0.01% significance level.

Roof collection and storage of rainwater for drinking

Collecting rainwater from house roofs can provide both a reliable supply and one that complies with World Health Organisation drinking water guidelines. Mass balance allowance allows the storage volume to be assessed. Pathogen die-off in accordance with first order kinetics shows that two or more tanks operating in series will remove substantially more pathogens than a single tank of the same capacity. Drop inlet pipe, bottom overflow and a floating arm draw-off can provide the quiescent conditions for Cryptosporidium oocysts to settle and achieve drinking water protozoa compliance without microfiltration or ozone disinfection.

Pressure drop and helium inlet in ITER CS1 conductor

A number of pressure drop measurements have been carried out at CRPP on a section of ITER cable-in-conduit conductor, using pressurized water at room temperature. The longitudinal friction factor is deduced for the strand bundle area and the central hole. Two layouts of radial helium inlet have been investigated and the measured radial pressure drop is assessed in terms of the equivalent conductor length producing the same pressure drop in axial direction.

Analyzing water distribution systems for swine growing and finishing units

An analysis procedure for livestock water distribution systems with nipple waterers is presented. The procedure uses the finite element analysis techniques to calculate the pressure distribution in a system with several branches and nipple waterers. The procedure also optimize the system for flow uniformity and cost. The formulation allows the use of the drop inlet as a discharge point to reduce the size of the solution matrix. The discharge parameters were developed at this inlet using waterer flow characteristics. The flow rate at each nipple waterer can be then calculated based on the drop inlet pressure. The solution for a typical network is presented. The method can be used as the basis for the design and evaluation of water distribution systems in swine growing and finishing units.

Model Study for Non-Standard Principal Spillway

Model tests were conducted on a non-standard principal spillway to evaluate the performance of the proposed drop inlet and impact basin and to evaluate the riprap size and placement downstream of the impact basin. An undistorted 1:24 model scale was used. The prototype pipe was 2.13 m (84 in.) in diameter. The outlet structure was a USBR Type VI impact basin. The design discharge was 43.9 m/s (1550 cfs). The spillway was a 1 3, two-stage, covered drop inlet with baffle trash racks and four low-stage orifices that occupied half the length of each side. The proposed design performed poorly with flow in the orifices. The trash rack was modified, performed very well, and was recommended for design. With the drop inlet in a berm [with the berm 0.610 m (2.0 ft) below the orifice invert elevations] the entrance loss coefficients were 0.28 and 0.26, respectively, with and without orifices. Locating the drop inlet in a berm will require riprap around the drop inlet entrance to prevent erosion of the berm. The outlet impact basin performed very well. There was minor scour over a considerable area downstream of the basin, but the riprap design is adequate.

Vortex Drop Inlet for Supercritical Approaching Flow

The inlet of vortex drops for supercritical approaching flow is discussed. Based on detailed experimental observations collected at various inlet geometries, the shape of vortex inlet was optimized. The geometry recommended is of spiral shape, and depends mainly on the shaft radius and on the width of the approaching channel. Particular features of the inlet are its wide domain of application regarding the Froude number and bottom slope of the approaching channel, and zero transverse inlet slope. The discharge capacities of vortex drops are shown to be of the same order for both sub- and supercritical approach flows. Further, the surface profile along the outer guiding wall is analyzed. It is found that both the Froude number of the approach flow and the radius of outer inlet wall influence significantly the maximum height of standing wave. A nondimensional surface profile along the outer wall is given, and prominent flow features in drop inlet structures are discussed.

Bend losses in drop inlet spillways

The drop inlet spillway consists of a vertical riser open at the top and connected to a horizontal conduit or tunnel at the bottom. A 90° change in direction is required at the connection between the riser and the conduit. In the interests of simplicity a square bend, sometimes called a miter bend, is often used for small unimportant structures. This type of bend produces separation zones and large eddy losses (bend loss). At the other extreme is the fully curved bend, commonly used for large shaft spillways. A properly designed curved bend will eliminate separation and minimize head loss. However, layout and forming for construction of a curved bend for a tunnel is complicated and expensive because the elbow surface is of double curvature.In this paper the results of hydraulic tests on five bend designs are presented. It was found that a simplified design with only an inside curve performed almost as well as the fully curved bend. It is suggested that the proposed design will meet the requirement for many low head drop inlets where use of the fully curved bend is not warranted but the square bend is not satisfactory.

Prototype Spillway Performance Verification

The flow performance of a prototype closed conduit spillway which could not be explained analytically was verified by a physical model. During the falling stage of the outflow from the reservoir, full conduit flow was observed in the Marsh Creek spillway even though the pool level was below the spillway crest. Engineers inspecting the spillway could not agreeably explain the flow performance. A physical model of the prototype was built and tested to verify the prototype performance. Tested with open and closed air vents, the model demonstrated the hysteresis shown in the falling limb of the prototype head-discharge relationship and the siphon-regulated flow observed in the prototype. Model observations indicate that the prototype flow control problem is the result of inadequate venting of the covered-top drop inlet.

Prediction of Sediment Basin Performance

ABSTRACT PUBLIC Law 92-500 requires the control and reduction of point and nonpoint pollution to meet the 1983 water quality standards. Current legislation in several states requires the use of sediment detention basins to control pollution from strip mining and construction activities. It is envisaged that sediment basins may successfully be employed to control the nonpoint pollution associated with agriculture and silviculture. This paper presents a mathematical model for describing the sedimentation characteristics of detention basins. Using data generated by the model, the significance of the factors determining sediment deposition in esti-mating basin trap efficiency and peak effluent sediment concentrations has been analyzed. Regression equations are presented for estimating trap efficiency and peak effluent sediment concentrations from basins equipped with either a perforated riser or a drop inlet riser. The effects of selective withdrawal from the basin have been studied as well as the effect of sediment accumulations in the basin on the trap efficiency. The model has been tested in simulation studies on several actual basins and appears to give a good estimate of measured trap efficiencies.

Erratum for “Crest Losses for Two-Way Drop Inlet”

Erratum for “Crest Losses for Two-Way Drop Inlet”

Closure to “Crest Losses for Two-Way Drop Inlet”

Closure to “Crest Losses for Two-Way Drop Inlet”

Discussion of “Crest Losses for Two-Way Drop Inlet”

Discussion of “Crest Losses for Two-Way Drop Inlet”