An experimental investigation of simultaneously developing, steady, turbulent fow under heating conditions in both straight and helically finned tubes with surface roughness (sand grain type) has been performed. Length-averaged heat transfer and pressure drop were obtained using air as the test fluid in twelve rough fin tubes and one rough tube without fins. Adiabatic friction factors and Nusselt numbers were measured for fin geometries of 18<=N<=60, 0.056<=H<=0.269, 7.562#mu#m<=Ra_(t,i)<=14.941#mu#m and 0 deg<=#gamma#<=26 deg> Turbulent flow operating conditions ranged from 7,500展开▼
机译：进行了在加热条件下同时在具有表面粗糙度（砂粒型）的直翅片和螺旋翅片管中同时产生稳定湍流的实验研究。在十二根粗翅片管和一根不带翅片的粗管中，使用空气作为测试流体，获得了平均长度的传热和压降。对于18 <= N <= 60、0.056 <= H <= 0.269、7.562＃mu＃m <= Ra_（t，i）<= 14.941＃mu＃m和0的翅片几何形状，测量了绝热摩擦系数和Nusselt数deg <=＃γ＃<= 26 deg湍流运行条件的范围为7,500 展开▼
