Conclusion and acknowledgment

 


Dimensioning of an hydraulic system

for water bombing from an aircraft


 

Conclusion

 

During our study, we created a program in order to simulate water bombing from an aircraft. This program gives good results according to the comparisons we made with our experiment. However, there are slight differences between the program and reality, which means that the program can be improved, especially regarding the aspects we neglected or simplified.

First, to go further, the acceleration phase should be included in the program.

 

Then, we think that the improvements should be concentrated on the modelisation of pressure drop. Indeed, we made several assumptions regarding this matter:

- we neglected the establishment length: in fact, the formulas presented on our website regardind regular and singular drop of pressure are only valid after a certain length of establishment. Before that, the laws are different and should be included in our program.

- we neglected the roughness of the walls of the tank. In fact, for high Reynolds, we choose to neglect the roughness by using the Blasius formula. To improve the program, the Colebrook formula should be used to calculate the coefficient of friction for high Reynolds:

$\frac{1}{\lambda ^2}=-2log(\frac{2.51}{Re \sqrt{\lambda}}+\frac{\epsilon}{3.7 D})$

 

Besides, in most cases, tanks in water bomber aircrafts are equipped with a vent, which fills the tank with air as it empties. This orifice modifies the pressure in the tank and hence the discharge. We gave some key ideas on this matter on the page:  Effect of depression in the tank.

 

Last, we think that our study could be useful in two domains: fire extinction and thermal imaging. We developped these points in the appendix:

 

Acknowledgments

 

We would like to express our gratitude to our supervisor Dominique Legendre whose expertise  and patience added to our understanding of the problem.


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