Question: A 250-V, 4-pole, wave-wound d.c. series motor has 782 conductors on itsarmature. It has armature and series field resistance of 0.75 ohm. The motor takesa current of 40 A. Estimate its speed and gross torque developed if it has a flux per pole of 25 mWb Answer: Step 1 Mechanical Engineering homework question answer, step 1, image 1 Mechanical Engineering homework question answer, step 1, image 2 Step 2 Mechanical Engineering homework question answer, step 2, image 1 Step 3 Mechanical Engineering homework question answer, step 3, image 1

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a)power for 6 cylinder is 300 kw for 1 cylinder 50 kw

$$\begin{gathered} P=p_{bemp}\times A\times l=18.5\times {10}^2\times \frac{\pi }{4}\times {D_b}^2\times D_b \\ {D}_b=0.325m \\ intake valve area A_{ i}=1.3{D_b}^2\times \left(\frac{{\left(P_s\right)}_{max}}{C_i}\right)=1.3\times 0.{325}^2\times \left(\frac{500\times {10}^3}{363.02}\right) \\ {A}_i=0.189m^{2 } for 2 valve 0.378m^2 \\ actual area 0.35\times 0.378=0.1323m^2 \\ dia of intake valve D_i=0.49 m \end{gathered}$$

b) $$\begin{gathered} valave area ratio \varphi =\sqrt{\frac{T_i}{T_{exh}}}=\sqrt{\frac{328}{873}}=0.61 \\ Exhaust valve area A_{exh}=0.61\times 0.1323=0.08m^2 \end{gathered}$$

c) $$\begin{gathered} flow through exhaust : \\ area of piston: P_s\times A_p=V\times A_i \\ {A}_p=0.0829m^2 \\ velocity of flow \left(V\right)=\frac{500\times {10}^3\times 0.0829}{0.189}=219.46m/sec \\ {V}_{exh}=0.6\times 0.08\times 219.46=10.626m^3/sec \end{gathered}$$