Provider of agricultural engineering, water management and water quality services
 

 

 

 

Proposal for an Experimental Procedure in Determining Orifice Discharge Coefficients
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


Ramy Atiyeh

Southern DataStream

132 North Lee St.

LaBelle

Florida 33935

ratiyeh@intellitemps.net

 

 

Summary:

 

 

Based on Loai Naamani study, a previous intern at Southern DataStream, we have noticed that the discharge coefficients through the orifices installed on the T-split system have been neglected, and not given the proper magnitude. Since it is of prime importance to our study and to be able to evaluate them exactly with the minimum possible errors, we will try to give in this document a thorough explanation of  an experimental procedure for solving this issue.

The experiment can be reproduced easily in our workshop with the existing material. No expenses are expected for that matter. A rough estimate of the time required is around 1 day, but the results will be an essential component in our project. If this proposal is approved, we suggest to start working on this issue the upcoming Monday July 29, 2002. The experiment will be repeated for different sizes of orifices. Data will be collected, calculated, and based on the results, recommendations will be issued regarding the design of the new water splitting system that we are currently working on.

 

 

Problem Definition

 

 

The design of the splitter system for the new generation of the water-sampling unit involves us in the study of the machine from a Fluid Mechanics point of view. Accuracy in sampling is of prime importance for researchers, which leads us to implement a new concept for the next generation of these machines. Time has shown that the present splitter systems are unreliable as well as unpredictable. Clogging problems from sand particles seems inevitable in addition to difficulties in maintenance and cleaning.  What we are proposing is to produce a simple experiment enabling us to obtain accurate data about the splitting system’s behavior. In order to calculate and to obtain a desirable water-sampling ratio, a thorough knowledge of the water flow through the discharge orifice leading to the sampling buckets is essential. Our experiment consists in determining empirical values for the friction and head loss of water flowing through different orifice sizes. The following proposal describes our understanding of the scope of work and our work plan.

 

 

Scope of work:

 

 

We suggest that our scope of work include the following:

 

·        Reproduce an experiment allowing us to determine the orifice coefficients essential to our design.

·        Collect all necessary data and document it.

After achieving successfully our task, we will issue recommendations from our experience; valuable for the design of the new generation T split systems of the water-sampling units as well as for future reference. As you requested, at a later stage, a program will be developed which will enable its user to easily determine all the useful parameters for building this kind of instrument.

 

 

Work plan:

 

 

Task 1: Experimental procedure

The material required for this experiment can be found in our workshop. The following describes the needed components:

·        1 bucket of water of a volume of 1 liter

·        Multiple plates having different orifice sizes

·        Drill

·        Silicon based glue

·        Caliper measuring device

·        Measuring tape

·        Stopwatch

·        Tap water

A hole is going to be drilled using the appropriate tools for the job slightly higher than the base of the water bucket. This will help on trapping sand particles at the bottom of the bucket instead of flowing through control orifice and clogging it. Then the round stainless steel plate, which controls the flow of water, will be glued onto the hole and closed temporarily to prevent any leakage. The bucket is then filled with a known volume of water. Time to empty the bucket through hole will be measured using the stopwatch. With the aid of the caliper, we can easily determine the diameter of the metal plate hole.  The measuring tape is used to determine the coordinates of the point where the water is hitting the ground. Please check reference 1 for further details.

 

 

Task 2: Evaluation of collected data and calculations:

The data collected will help us make all the necessary calculations for the determination of the overall orifice discharge coefficient. The following table summarizes the use of each one of the collected parameters:

 

Collected data

Use

Hole diameter

Calculate orifice area

Water hitting point coordinates

Calculate discharge velocity

Time

Calculate water discharge

Diameter of water exiting orifice

Calculate area of exiting jet

 

According to reference 1, the overall orifice coefficient is given by:

 Equation (a)

 is known as the contraction coefficient and is the coefficient of velocity. More information regarding the nature and the origin of these coefficients can be found in reference1.

 

The velocity of the free jet is calculated from the equation:

Where the abbreviations stand for:

Q: Water discharge rate.

A:   Area of orifice.

V:   Velocity of exiting free water jet.

x:    Abscissa measured from the edge of the water bucket to the point of water impact on    the ground.

y:    Ordinate equal to the height of the orifice from the ground.

H:   Available water head in the bucket.

g:    Gravitational acceleration or  .

 

is calculated using the following equation:

and :

Once all of these are calculated, the overall discharge orifice coefficient is found using equation (a).

 

 

Task 3: Interpretation and documentation of results:

The experiment will be repeated several times using the same orifice diameter to prevent any human error and a statistical study will be performed using MS Excel program to evaluate average values that will be used. All the results will be published on our websites (www.intellitemps.net/atiyeh and www.intellitemps.net/bizhanov) for future reference.

 

 

Schedule:

 

 

We propose to start executing our plan the upcoming Monday July 29, 2002, assuming that all necessary material and components are available in our workshop. We anticipate performing the work associated with task 1 within 2 hours of the experiment. Task 2 and 3 are estimated to take 3 to 4 hours of our time. The final calculated data and recommendations will be presented and posted on the web within late afternoon that date.

 

 

Cost estimate:

 

 

We estimate the cost of this experiment to be null given that the crucial components to the success of the procedure are available in our workshop. Otherwise a maximum estimate of 10$ is expected. All the needed hardware can be found in shops such as ACE Hardware.

 

 

Conclusion:

 

 

If you have any comment or questions about our recommended approach, or about any other aspect of this proposal, please feel free to contact us.

 

 

References:

 

 

1.     John Wiley & Sons, “Hydraulics – 5th edition”, February 1949.