Commit 1f971fc4 authored by Olivier's avatar Olivier

Exercises 2: fix two errors in questions

Two important errors in the problem questions are fixed, with my
sincere apologies:
* Question 2.3.2 could not be answered. The velocity is now given
  in the problem description and is not an unknown
* For questions 2.5.9+, the temperature at outlet must be taken
  as 165°C not 65°C.
parent c27258c7
......@@ -126,13 +126,12 @@ Balance of energy in a considered volume with steady flow:
% Fuel mass flow rough calculation: \dot Q = (\dot m * c_p * \Delta T)_air = 250 kW
% \dot Q / c_comb = 0,005 kg/s
At the outlet, the hot gases have pressure \SI{24,5}{\bar} and temperature \SI{1550}{\degreeCelsius}.
At the outlet, the hot gases have pressure \SI{24,5}{\bar} and temperature \SI{1550}{\degreeCelsius}, and exit with a speed of~\SI{50}{\metre\per\second}.
We consider that the air and gas have the same thermodynamic properties throughout the combustor ($c_\text{v} = \SI{718}{\joule\per\kilogram\per\kelvin}$, $R_\air = \SI{287}{\joule\per\kilogram\per\kelvin}$).
\begin{enumerate}
\item What is the volume flow at inlet and at outlet?
\item What is the flow velocity at outlet?
\item What is the power provided to the flow as heat?
\item What is the net force exerted on the gas as it travels through the combustor?
\end{enumerate}
......@@ -203,7 +202,7 @@ Balance of energy in a considered volume with steady flow:
\item What is the kinetic energy per unit mass of the air at point~3?
\end{enumerate}
Once it has passed point 3, the air undergoes complex loss-inducing evolutions (including going through a \vocab{shock wave}, where its properties change very suddenly), before it discharges into the atmosphere with pressure \SI{1}{\bar} and temperature is~\SI{65}{\degreeCelsius}.
Once it has passed point 3, the air undergoes complex loss-inducing evolutions (including going through a \vocab{shock wave}, where its properties change very suddenly), before it discharges into the atmosphere with pressure \SI{1}{\bar} and temperature is~\SI{165}{\degreeCelsius}.
\begin{enumerate}
\shift{8}
\item What is the fluid velocity at outlet?
......
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