Rhythmic fountain design study

Rhythmic fountain design study

designing a linear fountain with six independent groups; From hydraulic calculations to adjusting the movement of water and light

The rhythmic fountain creates visible movement by the programmed change of height and sequence of fountain activity. The quality of this movement depends on the coordination between the arrangement of the nozzles, the water circuits, the response of the pumps and the control program.

In this chapter, an educational example is examined from the beginning to the planning stage of the delivery test. The goal is to show the relevance of design decisions: how a visual demand translates into equipment grouping, pump operating point, schedule, and acceptance criteria.

This study is a hypothetical educational project. Employer name, actual location, customer satisfaction or performance outcome are not attributed to it. Nozzle sizes, efficiencies and response times are also assumptions and are not considered specifications of GSO products.

On the GSO website, rhythmic projects are presented as independent groups. In order to convert the current study into a real project file, the information of the same project should be replaced with assumptions according to the format of Chapter 41. GSO rhythmic fountain projects ^[301]

45–1. Definition of the problem and the need of the employer

It is assumed that a linear water feature will be designed for public viewing on the edge of a city sidewalk. The surrounding space is a place for citizens to pass and make a short stop, and it is also used at night.

The main demands are:

• creating visible movement along the sidewalk;

• Performing various programs without depending on music;

• The possibility of lowering the height in unfavorable wind conditions;

• Proper access for cleaning and repair;

• The possibility of continuing a simple show if a group leaves the circuit;

• Recording errors and simplifying the operator's work.

This fountain is intended for viewing from outside the pond. The water game or the entry of users to the pool is not in its user domain.

The depth selected in this table is a volumetric assumption and does not alone indicate the safety of the pond. Edge details, intrusion prevention, and communication with the travel path must be designed separately.

45–2. Spatial arrangement of nozzles

The nozzles are placed in two parallel rows. The length of the fountain is divided into six zones and each zone has four nozzles; Two nozzles per row.

Groups are identified from the beginning of the fountain to the end with the identifiers G1 to G6.

This arrangement enables three main patterns:

Linear movement: increase in height from G1 to G6 or vice versa.

Symmetrical movement: activity of G1 and G6 pairs, then G2 and G5, and then G3 and G4.

Alternation of groups: changing the height of odd and even groups.

The four nozzles inside each group have a common command; Therefore, the design has six independent water control units, not 24.

The exact location of the nozzles is determined after checking the spray, wind, visibility and service access points. The dimensions of the pond alone do not guarantee that the spray will remain in all modes.

Fig. 45-1 — Grouping plan

Draw a 18 x 5 meter pond plan. 6 areas with different colors and 24 nozzles in two rows. The main viewing path, the location of the equipment and the direction of the show should also be displayed.

* Subtitle: "Conceptual makeup of educational sample; The final distances are subject to the selection of equipment and the inspection of spraying.

45–3. Choosing the water circuit architecture

For this example, six independent circuits are selected:

Pond → dedicated suction → group pump → main line → four nozzle branches → water return to the pond

All circuits draw water from a common pool, but the output of the pumps is not connected to a common pressure collector.

This choice simplifies the setup of each group and reduces the pressure dependence of the groups on each other. On the contrary, the number of pumps, drives and service points increases.

Another option is to use a common pump and independent branch adjustment equipment. That option requires checking the pressure behavior when changing branches simultaneously and is not in the scope of this example.

For each circuit, the following facilities are provided:

• Disassembly for repair;

• Access to filter and pump;

• pressure and flow measurement place;

• The possibility of evacuation;

• Opening connection for equipment replacement;

• Initial setting of flow distribution between four nozzles.

The suctions and the return location of the purification circuit should be placed so that air entry, vortex, accumulation of pollution and inappropriate fluctuation of the surface do not occur.

45–4. Assumption of nozzle performance and flow rate calculation

For the long mode, the hypothetical performance of each nozzle is defined as:

These three values are the hypothetical specifications of a performance point. In the actual project, the relationship between height, discharge and head should be obtained from the manufacturer's documents or a valid test.

In this example, the total inlet head means the sum of the pressure head and velocity in the nozzle inlet reference section. If the catalog states only the inlet pressure, the velocity contribution must be properly included in the energy equation.

Flow of each group:

$Q_g=4\times 0.9=3.6m^3/h$

Convert to the appropriate unit of calculation:

$Q_g=\frac{3.6}{3600}=0.001m^3/s$

Total discharge of six groups in high mode at the same time:

$Q_{display}=6\times 3.6=21.6m^3/h$

This number is the circulation flow rate of the display circuits; The compensatory water consumption or the necessary flow rate for purification cannot be obtained from it directly.

45–5. Calculation of path loss of a group

For the critical path of a group, the following assumptions are considered:

Diameters are assumed internal diameters and should not be converted to nominal pipe sizes without checking.

Darcy's friction coefficient is assumed to be 0.025 for educational calculation. In the final design, this coefficient is a function of material, roughness, Reynolds number and flow conditions.

Flow rate:

$v=\frac{4Q}{\pi D^2}$

Longitudinal drop:

$h_f=f\frac{L}{D}\frac{v^2}{2g}$

Local drop:

$h_m=K\frac{v^2}{2g}$

With $g=9.81m/s^2$, the results are:

The drop of four parallel branches does not add up. To determine the pump head, the path to the critical nozzle is checked; Proper flow distribution between branches should be controlled separately.

The values of $K$ are assumed in this example for the set of components of each track. In the actual calculation, valves, strainers, elbows and other components must be entered according to the selected specifications.

45–6. Required head and initial pump selection

It is assumed that the reference section of the nozzle inlet is 0.15 meters above the free water level of the pond.

Required head of the circuit:

$H_p=H_{nozzle}+\Delta z+h_{loss}$

$H_p=5+0.15+0.873=6.023m$

Therefore, the consideration point for the initial selection of any pump is approximately equal to:

$Q=3.6m^3/hH\approx 6.1m$

Rounding the number to 6.1 meters is not a general design reserve or consistent recommendation for all projects.

The selection of the final model should be done by checking the actual curve of the pump and the circuit. The following still need to be controlled:

• Performance at all display heights;

• Permissible distance and flow range;

• Efficiency at work points;

• Adequate suction and margin conditions relative to required NPSH;

• Startup and shutdown behavior;

• Motor and drive compatibility;

• Required power in the entire operating range.

Placing the pump below the water level alone does not complete the suction check. Flatness drop, water temperature, location height and installation conditions are also effective.

Power calculation

Hydraulic power at the selected point:

$P_h=\rho gQH$

$P_h=1000\times 9.81\times 0.001\times 6.1=59.84W$

If the total efficiency from drive power input to hydraulic power is hypothetically 0.38:

$P_{electrical}=\frac{59.84}{0.38}\approx 157.5W$

For a preliminary estimate, the input power of each group in high mode is assumed to be about 0.16 kW.

This number is not the recommended nominal power of the engine. Also, if the efficiency used is only related to the pump, motor and drive losses should be considered separately. The efficiency breakdown of the pump and drive assembly is also explained in the KSB technical reference. Definition of efficiency in pumping system, KSB ^[302]

45–7. Water volume, level control and purification circuit

Initial geometric volume of pond water:

$V=18\times 5\times 0.35=31.5m^3$

In the actual volume, the occupation of the equipment and details of the structure and the volume of water in other parts of the circuit should also be checked.

When the show starts, part of the water is placed in the paths and fountains, and after stopping, it returns to the pond. Therefore, level control must distinguish between the short-term change caused by the display and the actual reduction of water.

For example, if the increase in the volume of water outside the pond during operation is hypothetically 0.3 cubic meters:

$\Delta h=\frac{0.3}{18\times 5}=0.00333m$

It means about 3.3 mm of average surface change. Local waves can exceed this value; Sensor location and control logic must take this into account.

Independent purification circuit

To show the calculation method, if the nominal circulation time is assumed to be six hours:

$Q_f=\frac{31.5}{6}=5.25m^3/h$

The number of six hours is an educational assumption and is not a general health standard for water fountains. The final treatment flow rate, disinfection method and monitoring program should be determined based on the application, water conditions and applicable requirements.

Also, volume circulation of water alone does not mean sanitary control. Cleaning surfaces, preventing sedimentation and biofilm, and managing operating conditions are important. CDC guidelines also consider cleaning and disinfection as part of managing decorative fountains. Management of Legionella in decorative fountains, CDC ^[303]

Place Figure 45–2 — Independent circuits

Show six circuits from the reservoir to the pumps and nozzle groups. Draw the filter circuit with a different color. Compensatory water, overflow and discharge should also be specified.

*Subtitle: "Independent treatment allows for water quality management without direct dependence on performance."*

45–8. Architecture of control and lighting

For each group, an independent command to drive the pump is considered. The central controller manages the timing and command amount of the groups.

In lighting, 24 RGB lights are assumed. If each light consumes three DMX channels in its selected mode:

$N_{channels}=24\times 3=72$

This number is only related to brightness. Actual lamp modes may have additional channels for overall intensity or additional functions; The addressing map must be set according to the selected device.

The control of the pumps in this example is done from the industrial communication path or the appropriate command of the drive. The number of lighting channels does not determine the number of pump commands.

The controller must have several specific modes:

Demonstration command should not be able to bypass necessary equipment protection. Selection of electrical protection, lamp power, matching and equipment suitable for wet environment is part of detailed electrical design and is not replaced by controller selection.

45–9. Convert target height to pump command

Three target heights are defined for the program:

These names refer to the water output, not the drive frequency percentage.

A 50% command does not necessarily create a 50% height. Pump curve, fixed head, path loss, nozzle characteristics and permissible working range affect the steering and height relationship.

An adjustment table must be prepared for each group:

First, the four nozzles inside each group are balanced; Then the groups are matched with each other. Increasing the pump speed to compensate for a blocked nozzle or unbalanced branch is not a good method of adjustment.

If the short height is not compatible with the permissible operating range of the pump, the selection of the equipment or the definition of the display must be modified.

45–10. Sample rhythmic program

For this design, a 120 second display cycle is suggested.

The duration of the transition, the minimum time to stay in each mode and the speed of command change are determined after testing the equipment. The table above is the initial artwork.

In the basic program, the height change is done with a controlled change of distance. Repeated turning off and on of motor power to create rhythm is not the basis of this example.

If the design requires a very fast water shut-off, the equipment suitable for that behavior must be selected from the beginning. The ability to run a slow wave is not the same as the ability to create rapid water shocks.

Place Figure 45–3 — Display timeline

Draw six rows for G1 to G6 and one row for light. Display the target height of each group during the cycle. The boundaries of scenes and soft transitions should be clear.

45–11. Response delay measurement and compensation

The time of sending the command is not the same as the time of seeing the height change. Lags can be caused by drive, engine acceleration, water circuit and fountain movement.

To teach the adjustment method, let's assume that the time for each group to reach 90% of the target height change is as follows:

This table is not the actual test result.

In this example, the faster group command can be sent later to make the groups reach the defined point almost simultaneously. With reference to 1.2 seconds:

$t_{delay,i}=1.2-t_{response,i}$

For G1:

$t_{delay,G1}=1.2-0.8=0.4s$

As a result, the G1 command is sent four tenths of a second after the G5 command.

This compensation is only valid for the same transition and test conditions. Upward, downward and start-to-stop responses may vary. The final criterion is to observe and measure the behavior of water.

In its services, Crystal Fountains also introduces sample testing, simulation, and display setup at startup to check performance and design realization. Crystal Fountains technical service and test ^[304]

45–12. The logic of wind, error and return to work

Wind can blow the spray out of the pool area. In this example, three situations are considered:

• Normal display;

• Low altitude display;

• Stop the show.

Wind speed limits should be determined from site conditions and spray test. Determining a fixed number is not suitable for all fountains.

To avoid frequent state changes near the boundary, the control logic must have a time delay and an appropriate difference between the entry and exit thresholds.

Soft stop is for normal display changes. In a critical safety event, the type and timing of the stop should follow safety logic and should not be delayed simply to preserve the aesthetics of the show.

45–13. Estimation of daily energy consumption

The input power of six pumps in high mode, based on the previous assumption:

$P_{display,max}\approx 6\times 0.16=0.96kW$

This number is not the constant power of the rhythmic program.

For daily estimation, the following assumptions are considered:

The full power of lighting is obtained from 24 18-watt lamps and a hypothetical efficiency of 90% for power supply:

$P_{lighting,input}=\frac{24\times 18}{0.90}=480W$

The average power of the pumps in the table is an independent assumption for estimation and is not accurately extracted from the time table of the display. In a real project, the power of each state and the duration of its presence should be recorded or measured.

The working hours of the treatment must also be determined according to the water management plan; This example number is not a general operating recommendation.

45–14. The order of implementation and adjustment

The sample run is scheduled as follows:

1. Consolidation of the architectural map, facility routes and service location; 2. Implementation of structure and passing parts and sealing control; 3. Installation of independent circuits and equipment ID registration; 4. Piping test and washing of routes; 5. Installation of nozzles, lights and control equipment; 6. Performing electrical tests before operation; 7. Dewatering and setting up the purification circuit; 8. Adjustment of individual groups; 9. Transient response measurement and program adjustment; 10. Integrated testing, training and delivery.

Final programming should be done after hydraulic adjustment. If nozzle height or branch flow is unbalanced, timing correction alone will not produce a regular display.

Figure 45–4 — Setting up groups

Choose a picture of the nozzle setting and a picture of a group test from the company's archive. The name of the real project and the subject of the photo should be included in the caption; The images should not be introduced as a hypothetical sample implementation of this chapter.

45–15. Exam program and acceptance criteria

Before delivery, it should be clear how each request will be checked.

Test conditions, such as wind, water level, filter condition and program mode, should be recorded. Without this information, comparing the results of two test sessions may not be valid.

Tolerances should be determined before the test and according to the equipment; They should not change after seeing the result just to get the job accepted.

45–16. Delivery documents and operation plan

The delivery file of this sample should include the following:

• Map of construction of water and electricity circuits;

• list of equipment with ID groups;

• Command table corresponding to set heights;

• program file and backup copy;

• Lighting addressing map;

• hydraulic and electrical test results;

• Error logic, wind and return to work;

• cleaning, purification and service program;

• The method of removing a group from the circuit;

• List of spare parts and order method;

• Register operator training.

The operator must be able to tell the difference between a program-induced drop in height, a clogged nozzle, a drop in water level, and a pump error.

Recording the status of each group is also important. If the G3 is out of circuit, the report should not just say "fountain is on"; The type of service provided and the existing limitation should be specified.

45–17. Study output and transferable experience

The preliminary calculation output of this example is:

This table is the result of a preliminary design and is not a performance report of an executed project. The final equipment model, suction conditions, actual drop coefficients, allowable working range and time settings should be completed in detailed design and testing.

The main experience of this study is the relationship between spatial grouping, independence of circuits and temporal response of water. A rhythmic program finds the expected quality when these three parts are adjusted together with the lighting and the result is checked from the actual location of the audience.