ThermofluidStream.Examples.SimpleAirCycle

[RaphaelGebhart]

Isses about ThermofluidStream.Examples.SimpleAirCycle;

1. I first thought the two sides of the model represent left and right pack of an aircraft. It took a while, until i understood, that this is not intended by the model and that the sides are actually two seperate models, that would never be combined into one aircraft. Therefor i suggest to highlight it by using seperate inlets and outlets for simple cycle and three wheel bootstrap cycle.

2. It would be beneficial to explain the ram air boundary conditions, i.e. p_in = 0.3 bar is the total pressure, T_in = -30 °C is the total temperature and p_out = 0.22 bar is the static pressure. Those values correspond to a static temperature T = -50.6 °C and velocity v = -203.5 m/s = 730 km/h. The static pressure and static temperature approximately correspond to an altitude h = 11.1km and a temperature difference of dT = 5.9 K to ISA0 (Actually h = 11.1km is slightly above the limit of troposphere h = 11km and i did not check the exponent in the tropopause but the 100m dont matter a lot i guess). That means: the boundary conditions are meaningful, but one needs some knowledge to check where they come from.

3. The fan has a pressure ratio pr = 0.53/0.3 = 1.76, the compressor has a pressure ratio pr = 3.0/2.5 = 1.2 which does not seem realistic to me. In my opinion the main reason is the rather bad implementation of ThermofluidStream.Processes.Internal.TurboComponent.dp_tau_const_isentrop. The example prooves that even for an official example we can not manage to design turbocomponents using the function. I made another issue for this implementation.

4. The simple cycle yields outlet temperature T_out = -2.37°C and a mass flow rate m_flow = 0.514 kg/s, the three wheel bootstrap cycle yields outlet temperature T_out = -1.57°C and a mass flow rate m_flow = 0.507 kg/s, i.e. from this example one would conclude that a simple cycle yields better performance (lower outlet temperature and higher mass flow rate) at lower complexity/weight/higher safety than a three wheel bootstrap cycle. I think we should reconsider that.

5. It might be beneficial to use displayInstanceNames, displayParameters, rename components and order them correctly to simplify the use of the example.

6. For a better overview sensors/displays might be beneficial too.

[IngelaLind]

* To further improve this we might consider using corrected speed and mass flow rates https://en.wikipedia.org/wiki/Compressor_map for compressor curves This is the form in which we usually receive component data from vendors.

[RaphaelGebhart]

Yes we might consider if some one wanna write a thesis and implement a nice compressor/fan/turbine component, im not sure if i have enough time...

[IngelaLind]

Sorry if I am a bit confused. I tried to applaud your suggestion on using corrected speed and corrected flow as an answer to the mail sent on #217, where that suggestion was included. But on the web page the text differs from the mails and the suggestion is only in #218. The mail for #218 is empty… But anyhow. Good suggestion!

[RaphaelGebhart]

Yes sorry, first I got it wrong :)

[tobolar]

@RaphaelGebhart Your comments are all fine. Additionally, this shall be documentad accordingly in the model. (I suppose you are not the only person who misunderstand the example.)