SimScale CAE Forum

Power Requirement for 80 knot Wave Piercing Tunnel Hull Surface Effect Catamaran

Simulation of a zero carbon high speed open water racing vessel to challenge existing records. NYC to Miami /London to Monaco.

The 16 x 4 meter vessel would be an Air Cushion Tunnel Hull Catamaran designed with Bow and Stern Hovercraft Skirts and the associated Lift Fan System.

Propulsion would be 2 x Waterjets each driven by 3 x 300 kW shaft through Electric Motors powered by Hydrogen Fuel Cells. Fuel System would be Liquid Hydrogen

Benefits of the propulsion system would include:

Zero Carbon emissions

Reduced fuel consumption by up to 50%

Better Sea keeping, more comfortable ride under all conditions

80 knots top speed

Hi @rsauter!

Do you have a project already uploaded and could share the link with us? :slight_smile:

Best,

Jousef

I have not uploaded the project because I don’t know what data is required

Cheers

Richard

Hi @rsauter,

First thing you will need is a geometry. From there we will work through the basic steps for each individual portion of the analysis. For your information, the analysis is split into 4 main parts:

  1. Geometry
  2. Mesh
  3. Simulation
  4. Validation

There are alot of intricate details within each of these areas. So lets start with the first one. Do upload your geometry in your preferred format first and we will discuss and correct that before moving onto meshing etc which then requires some specific data and assumptions.

Cheers.

Regards,
Barry

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Ok, I have to finalize the geometry by deciding on which of the 4 brands of 900kw Waterjets is best in this application. Each of the 2 asymmetric wave piercing tunnel hulls is 16 meters long, but their beam can be as narrow as the Waterjet inlet requires. The range of width (beam) between the 4 brands is 650mm, 690mm, 750mm and 810mm. Obviously the narrower the better.

As the vessel is supported by pressurized air, the displacement of the hulls is only relevant in regard to the pitch restoring moment and to seal off the sides of the air cushion, while the flexible skirts seal off the air at the bow and stern. This being the case extremely high length to beam ratios of over 24 to 1 are possible.

Other issues regarding the Waterjets relate to aeration at the inlets from air escaping from the captured air bubble (CAB) To prevent this problem which is better; an inlet at the stern with a flat bottom vs an inlet at the stern with a slight dead rise angle. Something CFD can help us determine. but which one to start with first?

Your thoughts?

Cheers

Richard

Hi Richard!

A lot of terms I have to understand first I have to admit :wink: Can you upload the geometry as mentioned by Barry and share the link with us? I guess your quantity of interest is the power output needed for 80 knot, so that’s something to start with or at least get the power output somehow via a result control (which I would need to check first).

Best,

Jousef

1 Like

I understand, so when I finalize the geometry I’ll provide you with the 3D files

Cheers

Richard

1 Like

Awesome Richard,

looking forward to it! Also some tips: The geometry has to be watertight and make sure to defeature your geometry as much as you can by removing very small fillets or components that won’t influence the flow, makes things much easier: “A good model is half the rent” :smiley:

Best,

Jousef

Thanks for everything, will do

Richard