Chart For Jet Design

[navarch_hish]

I am designing a jet drive based on the ship trust and Vs/Va.

I am looking for a chart which is a plot of Vs/Va and Vs/Vj (jet ratio)..

it has an optimum effciency line, what we do based on the ship's Vs/Va we find out Vs/Vj for optimum efficiency..

I am lookn for the chart, can anyone provide me the chart, it will be really helpful for my project work..

here

Vs= ship speed
Va = Velocity of advance

Vj= velocity of water at jet outlet..

ALso can anyone tell me jet effeciency applicable for cataramans operating in the range of 35 knots?

[alpamis34]

Hi mate,
The initial issue while designing a jet propulsion is to take the Vin/U ratio into account where Vin is the velocity of the flow in the duct just after the water intake gap. U is the velocity of the downstream flow ,basically the domain beneath the hull. If this ratio is too low, the duct will end up with a choked flow and if it is high then it will have erosion aand cavitation problems.

I dont have the charts on my pc but I have some on the books and as I have read from them , the efficiency of the waterjet prop. comes above 30 35 knots.I might give you some info as I go more throughly.

Cheers