4 TH EUROPEAN CONFERENCE FOR AEROSPACE SCIENCES (EUCASS) Copyright © 2011 by P. Roncioni and L. Cutrone. Published by the EUCASS association with permission. Preliminary Numerical Analysis of the LAPCAT MR2 Vehicle Configuration at Mach 8 Cruise Conditions Pietro Roncioni*, Luigi Cutrone*, Francesco Battista*, Marco Marini*, Johan Steelant** * Centro Italiano Ricerche Aerospaziali Via Maiorise, 81043 Capua (CE), Italy ** Aerothermodynamics and Propulsion Analysis Section (TEC-MPA), ESTEC-ESA Keplerlaan 1, P.O. Box 299, 2200 AG Noordwijk, The Netherlands Abstract This paper presents, in the framework of the European Union (EU) LAPCAT Program, a preliminary numerical analysis of the M8 vehicle in cruise conditions aimed at the assessment of the final configuration. Calculations for the combustion chamber analysis have been performed by means of the CIRA C3NS DB 3D code coupled with the integrated 1D module SPREAD. Some effects have been pointed out such as the effect of non-equilibrium recombination in the nozzle and the efficiency of the air compression process inside the inlet ramp. 1. Introduction At present time, the most promising technology for a drastic reduction of times to destination for long-distance (i.e. from Brussels to Sydney) civil flights is the hypersonic air-breathing propulsion. At hypersonic flight speeds, turbofan engines need to be replaced above Mach 3-4 by advanced propulsion concepts like ramjet/scramjet engines. This challenge is faced in the framework of the European Union (EU) LAPCAT Program [1] that aims at providing sound technological basis for the introduction at industrial level of innovative and advanced propulsion concepts on the long-term period (20-25 years), defining the most critical RTD-building blocks to achieve this goal and finally to investigate in depth these critical technologies by developing and/or applying dedicated analytical, numerical and experimental tools. Key objectives are the definition and evaluation of different propulsion cycles and concepts, the enhancement of integrated engine/aircraft performance, mass-efficient turbines and heat exchangers, and finally high-pressure and supersonic combustion experiments and modelling. In this scenario, CIRA activities are mainly devoted to the numerical analysis of components of the vehicles or, in the case of the M8 concept, to the vehicle itself. 2. Mission profile and activity description The activity of the present paper deals mainly with numerical simulations, at cruise flight conditions, of the LAPCAT M8 vehicle. The mission profile (Figure 1) of the M8 vehicle foresees an antipodal flight from Brussels to Sidney (> 16000 km) carrying 300 passengers with an efficient cruise at an altitude of about 30 km. The flight time is nearly 3 hours. A combination of different propulsion systems are employed for the acceleration phase of the mission, including turbojet engines based on an air-turbo rocket cycle (ATR), and dual mode ramjets [2]. For the overall performance analysis of the vehicle, the acceleration phase is of equal importance to the cruise flight, anyway this task will not be faced here. The ATR engines operate up to a Mach number of about 4.0-4.5 when the cycle is then switched to a Dual-Mode Ramjet. During previous phases of the LAPCAT program several configurations have been analyzed and a down selection is being done by a comparison of the main vehicle performances as aerodynamics, propulsion, mass estimates [1]. In this work the nose-to-tail (NtT) analysis for the MR2.4 version (Figure 2), conducted for what concerns the CIRA side, will be reported. The main aim of this work is to verify whether the aero-propulsive performances are able to sustain the vehicle (lift equal to the weight) and to maintain the velocity (thrust equal to the drag) at the cruise altitude (see Table 1). An analysis of the significant physical quantities as pressure and heat flux along the wall, average values of the main aerothermodynamic parameters along the engine axis, and the general behaviour of the vehicle will also be carried out.