Supersonic inlet buzz margin control of ducted rockets

Abstract

The maximum performance of a supersonic inlet will be achieved when operating as close as possible to its buzz boundary. In order to maintain high performance without crossing the buzz boundary, an active buzz margin predictor and controller is necessary. The goal of a control system is to acquire inlet buzz margin and maintain it as the designated value and predict inlet buzz before it occurs and then take some measures to buzz mitigation or inlet restart. The inlet buzz boundary and the margin of ducted rockets were first discussed and analysed. Then the dynamic mathematical model of a gas flow control system was established. Lastly, the inlet buzz margin controller of a ducted rocket was designed. Simulation results show that there exist antiregulation characteristics for gas flow control for ducted rockets, and it leads to the particularity of inlet buzz margin control for ducted rockets in contrast to liquid ramjet. The designed inlet buzz margin has to be bigger to avoid the appearing of inlet buzz because of anti-regulation characteristics; otherwise, the inlet buzz phenomenon probably appears. If the inlet buzz of the ducted rocket appears, the command of decreasing fuel flow could not be given immediately; otherwise, the inlet buzz will aggravate.

Buzz Cycle Description in an Axisymmetric Mixed-Compression Air Intake

“…In addition to Newsome [9], other researchers studied analytical modeling of the buzz phenomenon [10][11][12][13][14][15][16]. Sterbentz et al [10,11] considered a ram jet engine as a Helmholtz resonator and found that the buzz starts if the curve of the intake pressure recovery as a function of mass flow rate has a positive slope greater than a critical value.…”

Multi-objective regulating and protecting control for ducted rocket using a bumpless transfer scheme

“…A pressure-balanced gas regulating system, as given in the study of Shi et al, 23 is depicted in Figure 1. In the diagram, when the gas flow demand rises, the servo valve (2) can make the gas go into the valve head chamber (6) from a gas bottle (1).…”

“…Meanwhile, the valve head (5) goes forward along the valve stem (7), which makes the gas generator's (3) pressure rise but its throat area (4) decrease. The reader can refer to the study of Shi et al 23 for further details. The mathematical model of gas flow regulating system for ducted rocket can be described by the following three equations.…”

“…For not encountering inlet buzz, it is necessary to acquire and manifest the inlet buzz boundary. The buzz boundary of a supersonic inlet, given by Shi et al 23 and Chang et al 25 is adopted to investigate the protecting control design problems, which is defined as the maximum pressure ratio of inlet p u at different free-stream conditions.…”

Investigation on the anti-regulation characteristic of variable flow ducted rocket

“…11 The anti-regulation of gas flow incites sharply adverse variations of thrust and secondary combustor pressure, which may endanger the stability of the ducted rocket or lead to inlet buzz. [12][13][14] Thus, more attention should be paid on the investigation of the anti-regulation characteristic. Despite much progress in dynamic characteristics of VFDR, no consensus on the physical mechanism of anti-regulation has been achieved yet.…”