Effect of hole arrangement patterns on the leakage and rotordynamic characteristics of the honeycomb seal

The honeycomb seal is a vital component to reduce the leakage flow and improvethe system stability for the turbomachines. In this work, a three-dimensional model is established for the interlaced hole honeycomb seal (IHHCS) and the non-interlaced hole honeycombseal (NIHHCS) to investigate its leakage and rotordynamic characteristics by adopting computational fluid dynamics (CFD). Results show that the hole arrangement patterns have littleimpact on the pressure drop and turbulence kinetic energy distribution for the seals, and theIHHCS possesses a slightly lower leakage flow rate than the NIHHCS. Moreover, the numericalresults also show that the NIHHCS possesses a better rotordynamic performance than theIHHCS at all investigated conditions. Both seals show a larger k and a lower Ceff with the increase of the positive preswirl ratios and rotational speeds, while the negative preswirl ratioswould reduce the k and improve the Ceff. The NIHHCS possesses a higher absolute value ofFt for all operating conditions, this could explain the distinction of Ceff for both seals atdifferent working conditions.

3D Computation of Hydrogen-Fueled Combustion around Turbine Blade-Effect of Arrangement of Injector Holes

Recently, a number of environmental problems caused from fossil fuel combustion have been focused on. In addition, with the eventual depletion of fossil energy resources, hydrogen gas is expected to be an alternative energy resource in the near future. It is characterized by high energy per unit weight, high reaction rate, wide range of flammability and the low emission property. On the other hand, many researches have been underway in several countries to improve a propulsion system for an advanced aircraft. The system is required to have higher power, lighter weight and lower emissions than existing ones. In such a future propulsion system, hydrogen gas would be one of the promising fuels for realizing the requirements. Considering these backgrounds, our group has proposed a new cycle concept for hydrogen-fueled aircraft propulsion system. In the present study, we perform 3 dimensional computations of turbulent flow fields with hydrogen-fueled combustion around a turbine blade. The main objective is to clarify the influence of arrangement of hydrogen injector holes. Changing the chordwise and spanwise spacings of the holes, the 3 dimensional nature of the flow and thermal fields is numerically studied.

The cooling performance of three-row compound angle holes on the suction surface of a rotating turbine blade

Experiments were carried out to study the effects of compound angle,hole arrangement,and blowing ratio on the film cooling performance of multiple rows of holes on the suction surface of a turbine blade.The turbine worked at rotational speed of 600 rpm corresponding to the rotational Reynolds number of 5.36
105.Three rows of cylindrical holes arranged in line or in stagger were drilled on the rotor blade suction surface at the streamwise location of 12.4%,17.8%,and 23.2%,respectively.Three compound angles,with the same streamwise angle of 45but different lateral deflection angles of 45,0,and45,were studied.The film cooling effectiveness was obtained using pressure sensitive paint(PSP)technique with average blowing ratios varied from 0.5 to 2.0.The results showed that the application of compound angle changes the jet direction in the near-hole region and makes the film spread laterally.Compared with the film cooling without compound angle,using positive and negative compound angle can improve overall average film cooling effectiveness by about 20%and 25%,respectively.The effects of the secondary flow also can be weakened.A stagger film trajectory arrangement can achieve more uniform film coverage with higher overall film cooling effectiveness.The film trajectory arrangement of a positive compound angle injection is determined by the combined effect of hole arrangement and blowing ratio.While,the film trajectory arrangement of a negative compound angle injection is almost the same as the hole arrangement and nearly does not change with the blowing ratio.