There exist the optimal D1/H ((D1/H)opt) and optimal H/L ((H/
L)opt) which lead to the double minimum MTR ð~Rt;mmÞ of the
EGTB, but there does not exist an optimal H1/H which leads to
the triple minimum MTR of the EGTB. By increasing f and
decreasing H1/H help to improve the thermal performance of
the EGTB. However, the EGTB cannot be slender enough and
the cavity edge distance cannot be infinitesimal considering
the structural strength of the blade.