This paper describes the effects of measurement errors on the distribution of relative vertical distances (RVD) from which we may estimate the probability of vertical overlap of an aircraft pair. As typical examples of probability density functions, the double exponential distribution and the double double exponential distribution are assumed for height keeping errors. First, theoretical probability density functions (pdf) of RVD are derived for the both cases assuming that the pdfs of measurement errors are normally distributed. Then theoretical pdfs are compared with the empirical distribution generated by computer simulation in order to verify the theoretical values. Finally, some numerical examples for pdf of RVD are shown for several cases. Numerical examples suggest that the frequency in the central part (the core region) of RVD distribution in the presence of measurement errors becomes slightly less than that for the case that the measurement errors are not taken into account. On the other hand, the frequency in the tail region becomes slightly greater because of the presence of measurement errors. As a result, an estimate of the probability of vertical overlap for a given separation minimum (e.g., 1, 000ft or 2, 000ft) based on the RVD distributions would give a conservative value because of effects of measurement errors.
An orthogonal grid generation method for inlet geometries is developed using conformal mapping. In this method, the region on the physical plane is mapped onto the computational plane by one or two steps of conformal mapping; the mapping functions are determined numerically. A simple extension of this method allows the generation of three dimensional grids for asymmetric geometries. Grids of H-type are also generated through the fundamental mapping functions for C-type grids.
There is a suction flow in the unattached side output-port due to the existence of the splitter and the entrainment of the jet. This suction flow has been neglected in discussing the properties of the wall attachment device. However, it is found that the velocity and the flow rate of the suction flow will change considerably due to the shape of the devices. Since the suction flow in the unattached side output-port will exert an influence on the properties of the wall attachment devices, we can not neglect it in discussing the flow field in the devices. Hence, the purpose of this study is to clear the relation between the suction flow rate and the splitter distance. In addition, the suction flow rate is calculated numerically by referring to the reports on the attached jet, and calculated results are compared with experiments.
In recent aircraft with high by-pass ratio engines, the major noise source is the forward propagating fan noise from the engine inlet. Reported here is the investigation of the sonic inlet, which drastically reduces the abovementioned forward propagating fan noise. Model sonic inlets of both contracting wall type and translating centerbody type were designed by the newly developed analytical method based on flux analysis, and tested aero-dynamically and acoustically. Criteria for boundary layer separation, total pressure recovery characteristics, and crosswind characteristics of sonic inlet were obtained, and the model sonic inlet of the contracting wall type showed 21 PNdB noise reduction in model engine noise tests. Comparison between the analytical and experimental results proved the usefulness of the newly developed design method.
As the first step of the study of combustion control of solid propellants by electrical discharges, the effects of an arc discharge, which flows along the burning surface, on the burning rate and on the increase of enthalpy of the combustion product were investigated. For specially devised composite propellants, which are composed of Al powder and teflon powder, it was shown that the combustion can be controlled by an arc discharge; the combustion continues when the arc discharge is applied and is interrupted when the arc discharge breaks. In the present investigation, it was also shown that an arc discharge coupled with a high frequency electrical discharge has potentiality as an effective ignition method for solid propellants. For the use of this type of combustion control to an ignitor for a solid propellant rocket motor or to a control rocket motor, this method lacks flexibility in the configuration scale and needs a relatively large electric power at present stage.