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叙述的一种实验装置,可用来研究可贮存液体发动机的喷射区对声学干扰的整体响应特性.这一装置是以ONERA(法国国立宇航研究所)已成功地应用在固体火箭发动机中的方法为基础的.其中包括了用间歇调制喷管喉径的方法使一台模型小火箭的周期性振荡频率接近其一次纵向振型.在此情况下的喷射区的响应特性是由测量其一次纵向振型压力振荡的阻尼值来定量的,在以前的一篇文献中业已证明:在一台小型液体火箭发动机中,有可能触发出其一次纵向振型,并精确地测出不同阻尼值与参数变化之间的关系,例如用不同的喷注器、燃烧室压力、不同种类的燃料及喷管进口截面比等变化情况.这些实验采用了轴向喷注器,并假定推进剂的喷射和燃烧主要是受声压振荡干扰的(压力耦合).叙述在沿燃烧室全长的一半处装有径向喷注器的火箭发动机试验.试图用这种方式使喷雾和燃烧区受到声速扰动(速度耦合).并研究各种喷注器型式、燃烧室压力和燃料对声速扰动的影响.其间曾出现过若干自然的燃烧不稳定现象.还叙述用轴向喷注器进行的一些补充试验.对这两类实验结果加以比较即能鉴别压力耦合和速度耦合的不同特性.从某个技术角度看来,如果证实这类小型火箭发动机所获得的实验结果能转用于大型发动机,那么这种实验装置对研究液体火箭发动机的不稳定燃
Describes an experimental setup that can be used to study the overall acoustic response response of a jetted area where a liquid engine can be stored.This installation is based on the method of ONERA (French National Institute of Aeronautics) that has been successfully used in solid rocket motors as Which includes the intermittent modulation of the throat diameter of the lance to approximate the periodic oscillation frequency of a small rocket to its first longitudinal mode.The response of the injection zone in this case is determined by measuring its primary longitudinal vibration In this paper, it has been proved in a previous literature that in a small liquid propellant rocket engine, it is possible to trigger a first longitudinal vibration mode and to accurately measure different damping values and parameter variations For example, with different injectors, pressure in the combustion chamber, different fuel types and nozzle inlet cross-sectional ratios, etc. These experiments employed axial injectors and assumed predominately propellant injection and combustion Is disturbed by pressure oscillations (pressure coupling) .This describes a rocket engine test with a radial injector at half the full length of the combustion chamber. The fog and combustion zone are subject to velocity perturbations (velocity coupling) and the effects of various injector configurations, combustion chamber pressure and fuel on the speed of sound disturbances, during which a number of natural combustion instabilities have been observed, Some additional experiments were performed on the injector to compare these two types of experimental results to identify the different characteristics of pressure coupling and velocity coupling. From a technical point of view, if this small rocket engine proved to be able to get the experimental results For a large engine, then this experimental device for the study of liquid rocket engine unstable combustion