Module 4   :   Unbalance in Multicylinder Engines – In-line, V-twin and Radial Engines;  Balancing  Techniques.
Lecture 1 :    Unbalance in Multicylinder Engines – In-line, V-twin and Radial Engines;  Balancing  Techniques.

STATE OF BALANCE OF A RADIAL ENGINE

A radial engine is one in which all the cylinders are arranged circumferentially as shown in Fig. 4.5. These engines were quite popularly used in aircrafts during World War II. Subsequent developments in steam/gas turbines led to the near extinction of these engines. However it is still interesting to study their state of balance in view of some elegant results we shall discuss shortly. Our method of analysis remains identical to the previous case i.e., we proceed with the assumption that all cylinders are identical and the cylinders are spaced at uniform interval around the circumference. Thus the crank angle for an cylinder will be given by:

                                                                                                                                    (4.10)

Inertia force due to reciprocating parts of the cylinder is given by:

                                                                                                   (4.11)

Resolving this along global Cartesian X-Y axes, we have,

                                                     
                      (4.12)
   
                      (4.13)

When summed up for all the cylinders, we get the resultant inertia forces for the whole radial engine.

 


Fig. 4.5 Typical Radial Engine (Not to scale)
 

   
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