|
In modern aircraft, airborne weapon launching often causes inlet temperature transients of an axial flow compressor. As a consequence, the compressor may be forced away from its steady operating point and, depending upon its dynamic response, eventually there may be a complete breakdown in the compressor flow, thus leading to surge. This paper presents the authors' research on the unsteady response of the compressor to the temperature transients and the effect of fuel flow reduction on engine stability... In modern aircraft, airborne weapon launching often causes inlet temperature transients of an axial flow compressor. As a consequence, the compressor may be forced away from its steady operating point and, depending upon its dynamic response, eventually there may be a complete breakdown in the compressor flow, thus leading to surge. This paper presents the authors' research on the unsteady response of the compressor to the temperature transients and the effect of fuel flow reduction on engine stability when there is a sudden increase of engine inlet temperature. In recent years, some attempts have been made to simulate the unsteady response by using a mathematical model. Chamblee [5] presented a model in which the unsteady response is considered with steady state stage characteristics corrected. Das [6] described the unsteady response with a first order delay equation. In order to simulate the unsteady response more reasonably, the authors suggest a second order delay model combined with the "actuator-volume" model [7]. The unsteady response of the compressor to inlet temperature transients is then calculated, using the method of numerical integration. The calculated results are compared with test data and the calculated results supplied by other sources [4,10,11,12]. The comparison proves that the proposed models and calculation method are feasible. To the best of the authors' knowledge, there is no paper published on the effect of fuel flow reduction on engine stability. By way of analyzing the test curves of compressor surge caused by airborne weapon launching, the present paper proposes that the main reason of compressor surge is that the turbine nozzle row may be choked seriously during transient temperature rise at the engine inlet. Because fuel flow reduction can eliminate or reduce the degree of choke, it can play a role in preventing compressor surge. According to the above analyses, simulation calculations are carried out for different combinations of fuel flow reduction and temperature transients, using the second order delay model and the "actuator-volume" model. The calculated results are compared with the test curves from Ref. [1]. It is found the curve tendencies are consistent. 建立了压气机的激盘——容积模型及压气机对温度突升响应的二阶滞后模型。利用数值积分方法计算了温度突升对某涡喷发动机压气机稳定性的影响,并与发射武器的模拟试验结果及有关文献的计算结果进行了比较,证明了所用方法的可行性。对某涡喷发动机在不同温度突升和降油情况下的稳定性进行了模拟计算,确定出了降油量的大小对该发动机瞬态稳定工作边界的影响,计算结果与国外同类试验結果相比较,变化趋势是一致的。 It is the lateral error that we pay much attention when discussing the orientation problem of long-ranger weapons' launching. According to the design, the requirments of azimuth error are very rigorous. they can hardly be achie ved by general methods especially the short side propagations. In this paper, however, the author has concretely analysed the significant influnces of azimuth propagation such as focusing, plumbing and objective eccentricity. An observational method, called the method and... It is the lateral error that we pay much attention when discussing the orientation problem of long-ranger weapons' launching. According to the design, the requirments of azimuth error are very rigorous. they can hardly be achie ved by general methods especially the short side propagations. In this paper, however, the author has concretely analysed the significant influnces of azimuth propagation such as focusing, plumbing and objective eccentricity. An observational method, called the method and adjustment of angular obsefvations of short sides, is proposed. It can reduce above influences and improre the accuracy of emission greatly. 远程武器发射试验,对测绘保障提出了很高的要求,而武器的命中精度主要受横向测量误差影响。横向误差就是武器发射时的定向误差,包括起始大地方位角误差、连测基准边方位角误差及发射前的瞄准误差。本文讨论了这些误差对命中精度的影响,并对命中目标的精度作了分析,提出了一种短边传递方位的方法。 Provides the method used in undersea submarine positioning which combines the ground GPS positioning with undersea sonar.It also introduces GPS interface in the float and the software of the positioning system in detail.It can provide technical safeguard for inertial navigation readjusting and highly accurate positioning of weapon launching undersea. 提出了将水上GPS(GlobalPositioningSystem)定位技术与水下水声定位技术结合起来用于潜体水下定位的方法 ,详细介绍了定位系统中浮体的GPS接口技术及相应的软件模块。为在水下实现惯导系统的重调和武器发射时的高精度定位提供了技术保障
|