The values of the parameters in the Schmidt model influence not only the indicated work according to (10.2), but also the forced work. As an illustration, Figure 10.3 shows a sequence of three Schmidt gamma engine cycles with differing piston-to-displacer swept volume ratios, ? = V ₂ /V ₁. In each of the cycles, the displacer swept volume V ₁ and the mean cycle pressure are the same, and are taken as unity. Each engine cycle has the same temperature ratio ? = 0 .7 and phase angle ? = ?/2, and no dead space V _D = 0. The values of the swept volume ratio ? for the three cycles are 0.5, 1.0, and 1.5.

Figure 10.3: The effect of changing the swept volume ratio on the pressure volume cycle of a Schmidt gamma engine with fixed displacer volume. The table shows calculated work values and mechanical efficiency based on a mechanism effectiveness of E = 0.8.

The cycle diagrams are all drawn to the same scale. Because the displacer swept volume is the same for the three cases, the cycles in this example increase in size with ?. The table gives the work values...