Performance Envelope of a Turbojet Engine

[roldy]

In this project I'm tasked to do several things:

(1) Find the area at each station in the turbojet and calculate the thrust, $$\dot{m}_{fuel}$$ by calculating all relevant parameters at each station.

On-Design Values

$$M_0=0.8$$

$$\pi_c=15.472$$

$$M_2=0.5$$

$$\dot{m}_{corr,2}=35 kg/s$$

$$\pi_b=1.0, T_{t4}=1300K$$

$$\eta_t=0.86$$

$$T_0=230K$$

$$P_0=30000 Pa$$

$$RPM_{design}=70000 RPM$$

(2) After performing part (1), I need to develop the operating line of the engine. I've been working on this section but still need to iron out some issues.

(3) Develop the performance envelope of this engine.
I need to plot Thrust vs. flight Mach number for 3 different altitudes. On each of these plots, I'll have 5 lines corresponding to 5 different $$\dot{m}_{fuel}$$ values.

I have done this using MATLAB and also in Excel to double check my loop program. What I'm questionable about is the way the $$\dot{m}_{fuel}$$ lines cross over each other (looks like all at some flight Mach number between 1 and 2). I was wondering if this makes sense.

I also need to plot for three different altitudes the RPM vs. flight Mach number with 5 different fuel settings. What equation relates RPM to flight Mach number?

 

[Navin A S]

The RPM vs. flight Mach number plot will be determined by the turbojet's design parameters and the operating line. The equation that relates RPM to flight Mach number is given by:RPM = \frac{M \sqrt{\gamma R T_{t4}}}{\sqrt{\gamma R T_0}} \times RPM_{design}where M is the flight Mach number, \gamma is specific heat ratio and R is the gas constant.