Simulation on Heating and Current Drive Using Neutral Beam Injection with Variable Injection Angle on EAST

The heating and current drive using NBI （neutral beam injection） with a variable injection angle （the angle between the axis of the NBI system with the center axis of the injection window） on EAST is simulated by using NBEAMS code. The influence of the injection angle on the neutral beam current drive, heating efficiency and beam shinethrough power is discussed to explore the optimum injection angle for the EAST NBI system. According to the simulation, an injection angle of 19.5° is the optimum for EAST with its typical experimental parameters. With this injection angle, the increase in both the beam energy and power can improve the current drive and heating efficiency. The problem that the beam shinethrough power increases with the higher injection energy and power could be controlled through an increase of the plasma density.

Development of a 140 GHz Steerable Launcher for the HL-2A ECRH System

A new electron cyclotron resonance launcher system has been designed and installed on heating and current drive （ECRH/ECCD） the HL-2A tokamak to inject four beams and enable continuous millimeter-wave beam scanning independently in the toroidal and poloidal direc- tions for ECRH/ECCD experiments. The launcher is connected to four mm-wave lines capable of transmitting high power up to 3 MW with two 1 MW/140 GHz/3 s and two 0.5 MW/68 GHz/1 s beams. Based on ray tracing simulation using the TORAY-GA code, tile scanning range of wave beams is -15~~15~ in the toroidal direction and 0~~10~ in the poloidal one for 140 GHz beams, which could cover half of the cross section of plasmas and can satisfy the requirements of advanced physical experiments. The beam radii in the plasma is 17.1 mm and 20 mm for the two 140 GHz beams and 29.5 nnn for the two 68 GHz beams, respectively, allowing a very high localization of the absorbed power. The performance of the steering system was proven to be reliable and the linearity is perfect between the displacement of drive shaft and rotate angle of mirror. Addition- ally the injection performance of the wave beams was optinfized by simultaneously setting the injection angle and the polarization to realize desirable pure O- or X-mode injection.

Effects of Injection Angles and Aperture Ratios on Film Cooling Performance of Sister Holes

In this paper,to analyze the influences of the injection angles and aperture ratios (AR) of the primary hole and the side hole on the film cooling performance of a flat plate model,pressure sensitive paint (PSP) technology was used to study the forward and backward jet of a single hole and four sister holes,and a numerical simulation was supplemented to explore the flow structure of the sister holes.The sister holes had a better film cooling performance than the cylindrical hole at all blowing ratios (BR).The backward jet of the primary hole or the side hole could increase the spanwise film coverage of the sister hole.In this study,with the primary hole featuring a backward jet and the side hole featuring a forward jet,the film cooling performance was the best,11.9 times higher than the areal mean film cooling efficiency of the cylindrical hole when AR=1 and BR=1.5.At a low blowing ratio,the counter-rotating vortex pair (CRVP) of the side hole could suppress the strength of the CRVP of the primary hole.At a high blowing ratio,when the primary hole featured a backward jet and the side hole featured a forward jet,the CRVP of the side hole had the optimal performance for suppressing the CRVP of the primary hole.

Modulation of driving signals in flow control over an airfoil with synthetic jet

A new skill of modulating driving signals of a synthetic jet with low frequency is introduced to enhance the control authority.Based on dynamic mesh technique,the effect of flow control over a NACA0015 airfoil with a Synthetic Jet Actuator(SJA)has been investigated.The SJA is located at x/c=10%,and two jet injection angles of 90°and 30°have been considered.Flow structures indicate that modulation with low frequency can reduce the dissipation rate of vortices after they shed off the surface.Thus aerodynamic performance of the airfoil could be improved.For the injection angle of 90°,modulation can increase the control authority of the SJA.Compared to the unmodulated case,increment of lift-to-drag ratio is up to 15%.The modulating frequency corresponding to the largest increment is F_(M)^(+)≈1.For the injection angle of 30°,improvement of aerodynamic forces positively relates to momentum coefficient of the SJA.Due to the decrease of effective momentum,modulation degrades the effect of flow control.The opposite responses to modulation are believed to have a relationship with the variation of primary control mechanism.When jet injection angle varies from 90°to 30°,the primary mechanism changes from the interaction of vortices and waves to the direct momentum addition.The skill of modulation of driving signals is very useful for applications of SJA.