Rotor blade cooling

A rotor blade, comprising:

• a root portion;
• an airfoil portion extending radially outwardly from the root portion, the airfoil portion having a leading edge and a trailing edge, wherein the airfoil terminates radially at a tip portion;
• a forward primary cooling passage defined within the rotor blade and having a first inlet disposed along the root portion and a first outlet disposed along the tip portion to permit a coolant to exit the airfoil portion through the tip portion, wherein the forward primary cooling passage is in fluid communication with a first trailing edge cooling passage disposed along the trailing edge of the airfoil portion;
• an intermediate primary cooling passage defined within the rotor blade and having a second inlet disposed along the root portion and a second outlet disposed along the tip portion to permit the coolant to exit the airfoil portion through the tip portion, wherein the intermediate primary cooling passage is in fluid communication with a second trailing edge cooling passage disposed along the trailing edge of the airfoil portion;
• an aft primary cooling passage defined within the rotor blade and having a third inlet disposed along the root portion and a third outlet disposed along the tip portion to permit the coolant to exit the airfoil portion through the tip portion, wherein the aft primary cooling passage is in fluid communication with a third trailing edge cooling passage disposed along the trailing edge of the airfoil portion;
• and
• wherein the forward primary cooling passage, the intermediate primary cooling passage and the aft primary cooling passage are fluidly isolated from each other within the rotor blade.