Michael Zeutzius

Propulsion System for Hypersonic Space Planes

Because of its simple construction and low weight, combined rocket, ramjet, pulse-jet engines, or detonation enginesinsteadofturbojets,weretakenintoconsiderationaspropulsionforhypersonicaircraft.Combinedpropulsion requires an active control system to change the propulsion operation mode and to sustain the high-efe cient pulse combustion. Therefore, the transient behavior of the combustor is investigated to show the benee ts that can be gained, especially from a pulse combustor with active control. Several experiments were performed to survey system performance and to e nd suitable control parameters and strategies. Propulsion installation, including thrust augmentation, is considered to dee ne the tasks of the combustor controller. Nomenclature A = cross section b = fuel consumption c = sound velocity D = pipe diameter F = thrust f = frequency H = net calorie c value L = tail pipe length M = Mach number C m = mass e ow n = rotational speed P = pressure Re = Reynolds number T = temperature t = time u = velocity X, Y = coordinates a = angle of attack D P = pressure amplitude g = efeciency j = ratio of specie c heats q = density Subscripts and Superscripts

Active Control of Twin-Pulse Combustors

The pressure losses of steady-flow combustors can be overcome with so-called pressure gain or pulse combustors. Higher combustion efficiency and low NO x are the well-known advantages that outweigh the disadvantages of noise, combustor control, and lower operational flexibility. Inlets with variable cross section enable an active control of the combustor as gas generator for turbines. Therefore, a special emphasis is given to the design of the inlet, its control capacity, and its impact on combustor and turbine performance.

A propulsion for hypersonic space plane

To date, propulsion concepts for advanced space planes are based upon combined engines that include a turbojet as core engine. Turbojets provide sufficient start thrust but also cause a lot of integration problems. Due to its simple construction, combined rocket, ramjet, pulse jet engines or detonation engines instead of turbojets were taken into account as propulsion for hypersonic aircraft. The high unsteadiness of the running engine requires special control devices to meet the demands of the atmospheric flight. Therefore, several experiments were performed to find suitable control parameters, to give a survey on system performance and to show how to integrate such an engine into a hypersonic aircraft.

Pulse combustors with active control

The focus of the investigation presented here is the active control of combustors, especially pulse combustors. Active control is necessary for the stabilization of lean combustion in steady flows and pulse combustion as well. The investigation addresses combustor design, development methods, and a combustor model that is validated by experiments. A development method and how to obtain the characteristic parameters for the combustor model are explained in detail. Aside from the model development the performance and efficiency gain by using pulse combustion is also shown.

Studies on Pulse Jet Engine by Wind Tunnel Testing

Simple design and efficiency make pulse jet engines attractive for aeronautical short-term operation applications. An active control system extends the operating range and reduces the fuel consumption considerably so that this old technology might gain a new interest. The results on wind tunnel experiments have been reported together with the impact of combustion mode (pulse or steady) on system performance.

Study on Pressure Oscillation in a Supersonic Cavity Flow

In recent year, research and development activities for next generation supersonic transport are being car-ried out actively by the world aeronautical community. In a supersonic intake, a cavity plays an important role in the control of shock waves. The study of the supersonic internal flow with the cavity is important not only for resarch on industrial applications but also for basic research in gasdynamics. In the present study, the supersonic internal flow with cavities was investigated experimentally by a schlieren optical method and pressure measurements in the case of the flow Mach number 1.9 at the cavity entrance. The effects of configurations of cavity leading edge and porous wall on the flow-induced pressure oscillation were clarified qualitatively.