I need your vote for a new Rotary HCCI engine ! 4

[RodRico]

Fellow engineers,

This post promotes my design, but it's also informative for those curious about new developments in engine design, so I hope it's OK. Please accept my apologies if not.

I have submitted my patent pending design for a "Hybrid Miller Cycle Rotary HCCI Engine for RQ-7 Class Drones" in the "Create the Future" contest. You may find it by googling the engine name above or by visiting

https://contest.techbriefs.com/2017/entries/aerospace-and-defense/8090.

Preliminary analysis indicates power density (3 HP per pound) and efficiency (45% with 0.300 BSFC) comparable to a turbofan when operated at full equivalency. When operated in Low Temperature Combustion (LTC) mode, the engine still produces nearly 1 HP per pound but creates very few emissions. Because of its small 10" diameter and 6.5" thickness, multiple engines can be arranged in a clover-leaf pattern around a common shaft to yield 380 HP in a 24" by 6.5" volume. Another set of engines can be arranged behind the first to yield 760 HP in 24" by 16" volume. Note it's not mechanically efficient to add a third engine set due to limitations in my design.

I would greatly appreciate your support of my contest entry. Viewing my entry helps, but voting for it (which requires simple e-mail verification) helps even more. As it stands, I'm only one vote ahead of a "free energy" device ! That's just wrong ! Please circulate the link as widely as possible and encourage all your engineering friends and colleagues to help me win this contest! If I win the contest 100% of the money will go to funding 3D modeling of CFD/Combustion/Heat Loss by a consultant.

Thank you very much for your time and any support you can offer. If you have questions or comments, please post them here or on the contest site and I will answer them to the best of my abilities. I view criticism as being more valuable than praise when it comes to design, so don't hesitate to challenge my design (but please keep it respectful per normal engineering tradition).

Respectfully,

Rod Newstrom

P.S. Some may wonder why I targeted my contest entry at military drones. I would have preferred to emphasize the efficiency and low emissions qualities of my engine when operating in Low Temperature Combustion (LTC) mode. I targeted the military application instead because the administration wants to zero funding at the DOE/ARPA-E (who would normally fund such advances) while simultaneously increasing military budgets. I mention the RQ-7 drone, an unarmed surveillance drone, specifically because my engine fits in the volume and weight envelope of its current engine (the AR-741 Wankel), and the Army issued a Request For Information in 2016 for a replacement engine.

 

[RodRico]

CWBI,

Thank you for pointing that out. As I noted in prior comments, the next phase of development will be 3D Multi-Physics modeling encompassing CFD, combustion, heat transfer, etc. Perhaps I should have started with 3D Multi-Physics. It's time consuming and costly, however, so I started with basic feasibility analysis of first order thermodynamics, heat transfer, materials and stresses.

Rod

 

[LionelHutz]

I haven't seen anything that goes past this being yet another 3-D CAD experiment. So, I'm really not seeing much else useful to comment on besides your poor use of terminology.

 

[SwinnyGG]

How detailed have your gas flow analyses been to this point?

Your ports appear to have a very high area/perimeter ratio. Have you checked for localized supersonic limits on flow?

Checked for effects on charge homogeneity and droplet size during pumping through these highly restrictive orifices?

 

[RodRico]

JgKRI,

Port sizing was rudimentary, and I have done no spray analysis. My consultant is performing only first order analysis at present, suitable for a sanity check. Assuming it checks out, I'll fund him to do full CFD of gas and spray along with combustion, heat transfer, etc. I hope to offset the cost of that work by winning the contest mentioned in my original post. I'll fund it out of pocket if I don't win. I was fortunate in my career as an engineer, retired early, and can afford to carry this to prototype if need be. I'd rather not, however.

Rod

 

[enginesrus]

Just wow ! I see some critical heat treated hard parts with high contact stress, and a device that will be in need of constant low hour overhauls, and super costly parts to keep them in operation. Its kind of funny all the ideas that attempt to replace the crank chain in the reciprocating engine, and how it hasn't been done and will not be done until everyone settles on electric motors. Its just not me, but I vote for the electric motor its just way less monkey motion than that engine design and little to none wear parts that need constant attention.

 

[Lou Scannon]

IC reciprocating engines, turbines, and electric motors each have their strengths and weaknesses, and are applied accordingly.
I don't expect to see an electric motor generating electric power anytime soon.

"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz

 

[RodRico]

Lithium ion battery: 0.8 MJ/kg, motor efficiency: 95%
Diesel #2/JP-8: 45.5 MJ/kg, engine efficiency: 40%
Try to design a drone to carry a 1,000 pound payload for 24+ hours.
Electric needs better batteries to compete in aviation.

 

[GregLocock]

Oh. can a diesel powered heavier than air craft fly for 336 hours, 22 minutes and 8 seconds?

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[RodRico]

At under 20,000 feet so radar and cameras can be used to observe the ground?

 

[djhurayt]

http://www.reuters.com/article/us-m...SS&feedName=newsOne&google_editors_picks=true

 

[BrianPetersen]

Yup, and they're doing it with a traditional layout that will go down a standard production line and will be completely familiar to any technicians that may have to work on it.

I've known about this for a while. Other manufacturers have been attempting to get HCCI to operate over the whole speed and load range. Mazda did the common sense thing, "screw it" just put in spark plugs and use them as a redundant ignition source when the engine doesn't feel like operating in compression-ignition mode.

 

[3DDave]

Greg,

They are working on a plane that can reach 70,000 feet without a propulsion system, with a pilot, while not weighing less than one.

Thus far, high-endurance electrical aerial vehicles have been very limited. The Zephyr has no cargo capacity to speak of, low maneuverability, limited scaleability. Electrics are far from general purpose and occupy a niche similar in size to LTA.

 

[enginesrus]

Being an engine person my vote for electric motor was against this engine idea, not against ICR engines.
Hemi, Lincoln built a welder where the motor did run a generator for power, and there are many other such examples for generating power at other than 60Hz. When fuel cell technology is better they will generate the electricity.
Again has the TBO for this engine on paper been addressed?
I would like to know what the HP requirement is for this special drone engine?
As long as there are no special emissions requirements and restrictions it will be easier, to get the efficiency and power needed. Approximately what is the fuel load allowed in the drone?
So is there a video of a model of this engine that you propose running? If there are no running examples you are looking at many hours of time spent to find out it may not be feasible. I personally feel the materials will not last from the stresses. Its difficult to get solid tappets to last, how do you expect to transfer major HP through that cam and keep it lubricated? The side loads on the pistons and lack of advantage that recip crank arm has by using a cam ramp? ]
In this engine design you have lots to learn, and won't happen till you make the metal parts and give it a go.

 

[BigClive]

I don't think you can call this engine "rotary" as the pistons undergo cyclic acceleration. In a rotary piston engine the pistons travel in a circular path and only undergo a constant centrifugal force.

 

[RodRico]

Enginesrus,

The targeted drone is the RQ-7. It currently uses the AR-741 Wankel producing 38 HP at 7800 RPM. The Army issued an RFI in 2016 seeking an improved engine. You can google the drone and engine to learn more. There are no emissions requirements in the military application. Note the pistons in this engine are are under constant preload, and FEA has been completed on the preliminary design with normal 4x safety factor. There are no side loads on the pistons. Lateral thrust is from the camshaft behind the followers to the slot in the rotor. The engine is not built or running yet. It is still in preliminary anaysis. I hope to commence full 3D analysis with CFD, chemical kinetics, and heat transfer this year. I am hoping to use the contest prize money to fund that analysis, but will fund it myself if need be. Yes it will be a long slog, and it may end in failure, but I'm retired and have plenty of time and money.

BigClive,

You lost me when you said my engine is not like a rotating cylinder radial piston engine. Other than the fact I replace the crank mechanism with cams, I see no difference. Perhaps you can clarify further.

Rod

 

[gruntguru]

There will be side loads on the pistons - even if the cam is frictionless the force is applied to the piston normal to the cam contact.

je suis charlie

 

[RodRico]

grunt,

I'm probably screwing up terminology again. There are large lateral forces on the assemblies. The lateral travel is constrained, however, by support structures; the follower that's integral to the small inner piston rides between supports, and the outer cam shaft rides in a slot of the rotor. The intent of these supports is to take the load related to the cam so the piston rings aren't compressed against one side of the cylinder. The figures below show the assembly of the rotor and expose the supports around the inner piston cam follower as well as the cam shafts of the outer piston assemblies which pass through slots in the rotor. Note the supports around the inner piston follower are the soft metal of the rotor body while the slots containing the cam shafts have polished tool steel inserts. Also note the center of mass of the outer piston assemblies is centered on the cam shaft.

Rod

 

[BigClive]

To continue on the theme of whether the engine is rotary or not: - with the use of a four-cornered cam ring the pistons wouldn't follow a circular path - thus they would accelerate back and forth. Having the pistons travel in a circle would be my definition of a "rotary" engine. If you had just one circular cam ring - then the engine would be rotary.
I may have missed it - but just why are you proposing a rotating-block engine? Rotating block engines (even if they are true rotaries) have many disadvantages and very few advantages.

 

[RodRico]

BigClive,

I see what you're saying, but personally feel it's a legitimate rotary. Patents are filed with classifications to help folks find those that are relevent to a field. Each classification is accompanied by a description, and mine complies with the description of a rotating cylinder, radial engine. If you look for other engines in that class, you find the classic radial rotaries of years gone by.

Rotating cylinder engines do have one key advantage... only one fuel injector is needed per cycle to service any number of cylinders. Though I show 12 cylinders in the illustrated instantiation, there are only four fuel injectors (one per complete cycle separated by 90 degrees). The mechanical aspects are also simpler with a rotating block. Visualize how to spin that central shaft *and* the outer cam rings while plumbing air passeges from the outer cylinders to the inner *and* incorporating an electric motor/generator into the engine. It's a complicated mess!

Traditional rotating cylinder engines have two key disadvantages IMHO. The largest is getting the devices that initiate combustion (spark plug or fuel injector) into the cylinders. The common approach is to spin the spark plug/fuel injector with the cylinder or to have the cylinders rotate past a stationary "head." The former leads to challenges in passing fuel or spark energy to the rapidly rotating spark plug or injector while the later creates complications in high pressure seals and combustion. I sidestep these problems using HCCI.

Another problem with rotating block engines is, of course, centripetal forces and rotational inertia. Centripetal forces are included in my stress analysis which looks OK, but it *will* limit the diameter/RPM of the engine... The 7800 RPM engine doesn't scale well up to larger sizes, for example. Rotational inertia will certainly affect acceleration, but the rotor is made of aluminum or titanium (depending on RPM) and doesn't weigh any more than flywheels and balancers commonly found on 100 HP class engines. In versions equipped with the electric motor/gen, I will also have the torque of the electric motor to aid acceleration.

Bottom line: the rotating block just emerged as the cleanest answer given use of HCCI. Note that my patent explicity states that the core claims apply to an engine with a rotating *or* stationary block (as do most patents in this class).

Rod

 

[enginesrus]

Very expensive and difficult parts to manufacture. And many wear points to lubricate, and saying nothing about the
lack of proper tribological design for the bearing areas. So what is max weight the engine design can be, and hp? Maybe I should enter, how and where to do that? My design has way less parts.

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