## 3 Properties of the Mixture of Jet A-1 Aviation Kerosene and FAME Biofuel
#### 4.1.4 The Course of Changes in SJE-20 Parameters When Using a Mixture of 70% Jet A-1 and 30% FAME  
The fourth series of measurements was aimed at determining the parameters of the experimental SJE-20 during its operation with a fuel mixture consisting of 70% Jet A-1 aviation kerosene and 30% FAME biofuel (see Figure 7 and Table 9). The measurements followed immediately after the previous series of measurements. The temperature of the SJE-20 engine before starting was t\({}_{\text{MPM}}\) = 71.0 \({}^{\circ}\)C. The starting process of the engine, at the given temperature state of the engine, took place normally. The mixture was ignited only at 4.6. seconds, corresponding to starting the engine with pure Jet A-1 aviation kerosene.  
Figure 6: Graphic course of changes in SJE-20 parameters when using a mixture of 80% Jet A-1 aviation kerosene and 20% FAME biofuel.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline Parameter & **20 th Second** & **25 th Second** & **30 th Second** & **35 th Second** & **40 th Second** & **45 th Second** \\ \hline Temperature t\({}_{0}\) [\({}^{\circ}\)C] & 28.8 & 27.5 & 27.5 & 27.5 & 27.6 & 27.6 \\ Temperature t\({}_{2t}\) [\({}^{\circ}\)C] & 55.3 & 85.7 & 93.4 & 92.6 & 102.5 & 95.5 \\ Temperature t\({}_{3t}\) [\({}^{\circ}\)C] & 1094.1 & 956.8 & 986.6 & 1003.9 & 1011.2 & 1026.6 \\ Temperature t\({}_{4t}\) [\({}^{\circ}\)C] & 765.0 & 604.9 & 615.9 & 634.8 & 654.7 & 665.9 \\ Pressure p\({}_{2t}\) [Pa] & 260,738.0 & 273,515.4 & 269,633.5 & 268,204.3 & 269,522.1 & 271,780.1 \\ Pressure p\({}_{3t}\) [Pa] & 181,221.0 & 192,419.9 & 187,818.4 & 185,895.0 & 186,290.9 & 189,165.8 \\ Flow Q\({}_{\text{fuel}}\). [L.min\({}^{-1}\)] & 1.164 & 1.299 & 1.264 & 1.261 & 1.247 & 1.249 \\
**Revolutions n [min\({}^{-1}\)]** & 42,228.6 & 46,770.6 & 46,702.6 & 46,798.9 & 46,657.1 & 46,786.4 \\
**Thrust F.T. [N]** & 418.7 & 460.9 & 460.8 & 454.7 & 456.4 & 462.7 \\ \hline \hline \end{tabular}
\end{table}
Table 8: Mixture of 80% Jet A-1 aviation kerosene and 20% FAME biofuel, 1 st launch (40 th second).  
The addition of 30% FAME biofuel to Jet A-1 aviation kerosene resulted in an increase in the maximum total gas temperature in front of the gas turbine \(\Delta\)t\({}_{3\text{,max}}\) by 13.35 \({}^{\circ}\)C and a decrease in the maximum total gas temperature behind the gas turbine \(\Delta\)t\({}_{4\text{,max}}\) by \(-\)9.7 \({}^{\circ}\)C, as well as a decrease in the total gas temperature in front of the gas turbine \(\Delta\)t\({}_{3\text{,max}}\) by \(-\)3.4 \({}^{\circ}\)C and a decrease in the total gas temperature behind the gas turbine \(\Delta\)t\({}_{4\text{,max}}\) by \(-\)6.4 \({}^{\circ}\)C. The value of the total air temperature behind the compressor \(\Delta\)t\({}_{2\text{}}\) decreased by \(-\)9 \({}^{\circ}\)C, the value of the total air pressure behind the compressor \(\Delta\)p\({}_{2\text{}}\) decreased by \(-\)1493.7 Pa, and the value of the total gas pressure in front of the gas turbine \(\Delta\)p\({}_{3\text{}}\) decreased by \(-\)3217.2 Pa. The thrust of the SJE-20 engine was reduced by \(\Delta\)F\({}_{\text{T}}\) = \(-\)2.1 N, with a simultaneous increase in fuel consumption \(\Delta\)Q\({}_{\text{fuel}}\). = 0.051 L.min\({}^{-1}\).