Abstract
The multiduct inlet for turbine-based combined cycle engines receives a lot of attention on its aerodynamic performance. Aside of the most studied mode of transition processes, another significant severe issue regarding the aerodynamic performance of the turbine duct (T-duct) at ground states has rarely been investigated which indeed directly determines the operability and reality of similar engine systems; this issue will be addressed in the present work. Our numerical and experimental studies of an inward-turning tetraduct inlet indicate that the performance of the T-duct is seldom affected by the angle of attack, which however is of crucial importance for takeoff/landing of flight vehicles. The two T-ducts exhibit weak asymmetrical aerodynamic performance during experiment due to nonsynchronization as well as mechanical oscillation of the two turbine engines. With increasing inflow speed, the surface pressure and the total pressure recovery increase accordingly. At Ma∞=0.24, the total pressure recovery achieves 0.96 at the exit of the turbine duct which is acceptable for the engine to generate sufficient thrust for horizontal takeoff. A further quantitative comparison between simulation and experiment reveals a maximum deviation of only 3% in terms of both surface pressure and total pressure recovery.
Highlights
Hypersonic travelling has attracted intensive attention from both scientific and commercial communities recently
The total pressure recovery in the turbine duct (T-duct) can be split into two parts, i.e., the left part which is filled by flow with low energies and the right part that is filled by flow with high energies
The axial pressure distributions on surfaces of the two T-ducts under different rotational speeds of the turbine engine are provided in Figure 7, where panels (a)–(d) correspond to the axial pressure distributions of the right T-duct in the xy plane, the right T-duct in the xz plane, the left T-duct in the yz plane, and the left T-duct in the xz plane, respectively
Summary
Hypersonic travelling has attracted intensive attention from both scientific and commercial communities recently. The difficulty lies in the propulsion system which must satisfy the requirement of horizontal takeoff/landing and generate sufficient thrust at subsonic, transonic, supersonic, and even hypersonic speeds. The requirement of a wide working range promises that the only solution is an efficient combination among turbine, rocket, ramjet, or scramjet engines. Various concepts of a combined cycle engine have been proposed by different organizations historically. The Long-Term Advanced Propulsion Concepts and Technologies (LAPCAT) in Europe is aimed at developing a hypersonic transport aircraft with Reaction Engines Ltd. The Scimitar engine is based on the combined concept of a precooling turbine engine and ramjet technology [1, 2]. The Japan Aerospace Exploration Agency (JAXA) has started the research of a hypersonic combined cycle engine since the
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