Fuel cell flow field channel with partially closed end

1. A fuel cell flow field plate, comprising:

a first fuel cell flow field section having a plurality of first channels that are parallel, each first channel having an unobstructed channel inlet and an unobstructed channel outlet; and

a second fuel cell flow field section having a plurality of second channels, each second channel having a channel inlet section and a channel outlet section, wherein at least one of the channel inlet section or the channel outlet section includes an obstruction member that partially blocks flow through the respective one of the channel inlet section or the channel outlet section, and the second fuel cell flow field section is in flow-receiving communication with the first fuel cell flow field section.

2. The fuel cell flow field plate as recited in claim 1 , wherein each second channel comprises a flow passage between elongated channel walls, and the obstruction member extends into the flow passage between the elongated channel walls.

3. The fuel cell flow field plate as recited in claim 2 , wherein the obstruction member comprises a first protrusion that extends from one of the elongated channel walls into the flow passage.

4. The fuel cell flow field plate as recited in claim 3 , wherein the obstruction member comprises a second protrusion that extends from the other of the elongated channel walls into the flow passage.

5. The fuel cell flow field plate as recited in claim 1 , wherein the obstruction members block greater than about 70% and less than about 90% of a nominal cross-sectional area of the second channels.

6. The duel cell flow field plate as recited in claim 5 , wherein the obstruction member blocks about 80% of the nominal cross-sectional area.

7. The fuel cell flow field plate as recited in claim 1 , wherein the obstruction member includes a first closure member that extends adjacent to one of the channel inlet section or the channel outlet section to partially block flow through the flow passage.

8. The fuel cell flow field plate as recited in claim 7 , including a second closure member that extends adjacent the other of the channel outlet section or the channel inlet section to partially block flow through the flow passage.

9. The fuel cell flow field plate as recited in claim 1 , wherein the channel outlet section includes an outlet opening at least partially formed by the obstruction member and the channel inlet section includes an inlet opening that is larger than they outlet opening.

10. The fuel cell flow field plate as recited in claim 1 , wherein each second channel comprises a curved channel surface.

11. The fuel cell flow field plate as recited in claim 1 , wherein each second channel extends between channel walls that are angled relative to one another such that the second channel is tapered.

12. The fuel cell flow field plate as recited in claim 1 , wherein each second channel includes a flow passage between a bottom wall, elongated side walls, an open top, a channel inlet section at one end of the elongated side walls, and a channel outlet section at another end of the elongated side walls, wherein the obstruction member includes a protrusion that extends partially into the flow passage from one of the walls, and the protrusion includes a curved surface.

13. The fuel cell flow field plate as recited in claim 1 , wherein the obstruction member includes a first plate that is movable to adjust the partial blockage of the flow.

14. The fuel cell flow field plate as recited in claim 13 , wherein the obstruction member includes a second plate that is movable independently of the first plate to adjust the partial blockage of the flow.

15. A fuel cell flow field plate, comprising:

a first fuel cell flow field section having a plurality of first channels, each first channel having a channel inlet section and a channel outlet section, wherein at least one of the channel inlet section or the channel outlet section includes an obstruction member that partially blocks flow through the respective one of the channel inlet section or the channel outlet section; and p 1 a second fuel cell flow field section having a plurality of interdigitated second channels including entrance channels with fully open inlets and fully closed outlets and exit channels with fully open outlets and fully closed inlets, and the second fuel cell flow field section is in flow-receiving communication with the first fuel cell flow field section. channel inlet section or the channel outlet section includes an obstruction member that partially blocks flow through the respective one of the channel inlet section or the channel outlet section; and a second fuel cell flow field section having a plurality of interdigitated second channels including entrance channels with fully open inlets and fully closed outlets and exit channels with fully open outlets and fully closed inlets, and the second fuel cell flow field section is in flow-receiving communication with the first fuel cell flow field section.

16. The fuel cell flow field plate as recited in Claim 15 , wherein the obstruction member includes a first plate that is movable to adjust the partial blockage of the flow.

17. The fuel cell flow field plate as recited in Claim 16 , wherein the obstruction member includes a second plate that is movable independently of the first plate to adjust the partial blockage of the flow.

18. The fuel cell flow field plate as recited in Claim 15 , wherein a flow path extends through the first channels to the entrance channels, through the entrance channels into a gas exchange layer, through the gas exchange layer into the exit channels, and through the exit channels.