微激励振荡射流集中耗散气波制冷机制及强化

To overcome the drawbacks of static gas wave refrigerator, a novel refrigeration mechanism with micro incentive jet oscillation and centralized dissipation in dual-opened short pulse tubes is developed. Several radical innovation theories involved in the study must be studied thoroughly: control of unsteady high speed jetting boundary layer, mechanism of micro incentive jet oscillation and its geometry optimization, dynamic thermal separation in dual-opened short pulse tubes, and constraint mechanisms of end outlet boundary condition..The novel refrigeration mechanism can eliminate reflective shockwaves and can overcome the shortcomings of energy loss on former jet oscillation and tube vibrations. The research also includes: high efficient inspiration and induction mechanisms of micro jet, corresponding properties and oscillation control or intensification of major jet; the relationship between waves motion characteristics and energy transfer, the relationship between temperature differences, pressure amplitude and process efficiency under condition of the same chamber for short pulse tubes; study on dynamic control measures, energy losses of mixing, elimination of reflective shocks, and structural optimization. Based on the above research, a novel high efficiency gas wave refrigeration equipment without movement parts will be developed. The study findings in the study will contribute to the development of the theory of jetting control and gaswave applications.

针对目前静止式气波制冷机制的缺陷，提出以微射流高效激励、低损失地产生可调控的附壁振荡射流，再进双开口短气波管中高效传输分离能量，最后在共容腔中集中耗散的新型高效气波制冷机制。研究伴随两项重大变革所呈现的理论新问题：高速可压缩射流非定常流动的边界层分离控制；微射流激励射流振荡的高效机理、几何优化机制；双开口短气波管内能量的动态分离与制冷，末端开口边界条件的约束机制等。该制冷机制研究能避免原机制射流自激励振荡所产生的能量损失，和消除反射激波提高效率，及克服长气波管的振动与可靠性缺陷。.研究微射流的高效激励、诱导机制和主射流的响应性能，振荡控制与强化。研究双开口短气波管在末端共容贯通的边界条件下，管内波系的运动特征和能量传输转换关系，管内温差、压力振幅与过程效率之关系及能动控制措施；研究混合能损与反射激波的消除、流道参数优化等。以期创新高效无动件气波制冷装置，发展高速射流控制与气波应用理论。

以分散压力能高效利用为背景，研究外引激励流高效产生可控附壁振荡射流，再高效分离耗散能量的新型气波制冷机制。研究伴随这两项重大变革所呈现的新科学问题、和指导应用的普遍规律。包括提升振荡能效的宏观、微观机理，能损原因与抑制方法；振荡器几何尺寸对激励灵敏度和能效的耦合机制与几何优化；外激励流参数与时变模态对激振能力和振荡能效的关联影响；创新型中部阻波腔气波管机理与波系分析、制冷效率影响规律；气波管入口高效射流模态和实现方法；外激励二级附壁振荡模式。. 项目研究得到重要结果：(1)外激励振荡法能效率很高，膨胀比2时总压保持率K达85%，远高于射流反馈自激励振荡法；外激励流升压快、总压高、持续激励，能加速主射流切换，降低卷吸、碰撞及三通流动损失；持续压主射流不脱壁，抑制边界层分离，特别是可自膨胀加速，避免主射流抽吸动能损失。(2)获得外激励附壁振荡器几何参数对易振性和能效制约关系及优化结果：S/W＝0.3～0.4，L/W≈1.2，H/W≈4，h/W≈0.9，激励流与主射流流量比0.3，K可达90%，减小膨胀比K上升。(3)激励流总压降低、中途衰压，会显著降低振荡能效，故原有反馈自激励方式能效难提高；而外激励流参数20%的变化，对振荡稳定性和总压保持率影响轻微。(4)揭示现有气波管缺陷，发明了中部阻波腔式气波管，能强力抑制反射激波回热，和匹配管内波系，制冷效率比现有高效末端吸波腔式管相对高约10%，低谷高约18%。(5)证明了静止式气波机以射流单摆振荡注气会严重限制其制冷效率，减小占空比、使各管注气时长和周期均等是打破效率瓶颈的关键。(6)发明了二级（两次）射流附壁振荡器，高效获得1/4占空比时均脉冲，使气波管相对效率提高约40%。. 研究结果对于高速流动的主动控制、边界层流动分离的主动干预、抑制，不定常流动能量传递等当今流体力学热点研究课题，提供参考和借鉴，且有广泛应用前景：创新高效可靠的附壁振荡器，提高气波制冷机制冷效率，小膨胀比振荡脉冲用于消除流动死区、增强传质，还可用于生化反应器、污水处理、高效传热等领域。