Marco A. C. Alves - marco@asap.iae.cta.br
Helder F. F. M. Carneiro - helder@asap.iae.cta.br
João R. Barbosa - barbosa@mec.ita.cta.br
Instituto Tecnológico de Aeronáutica, Departamento de Energia
12228-900, São José dos Campos, SP, Brazil.Paper S24P01

Luis E. Travieso - travisan@adinet.com.uy
Universidad de la Republica, Herrera y Reissig 565, Montevideo, Uruguay

Pericles Pilidis - p.pilidis@cranfield.ac.uk
Cranfield University, SME, Beds, MK43 0AL, UK

The design point performance of reheat gas turbines for combined cycle is investigated in this work. A comparison of reheat and simple cycle results is used to draw the main conclusions. Some conclusions available in the literature were confirmed; such as the fact that reheat increases the specific power and reduces the efficiency of the gas turbines. The latter is mainly a consequence of the increase of the amount of energy (heat) lost in the exhaust, represented by an increase in turbine exhaust temperature. Thus, the reheat cycle gas turbine can be considered well suitable to combined cycle. In this case the reheat combined cycle efficiency increases, compared to simple cycle, in spite of the reduction in efficiency of the gas turbine reheat cycle, with the advantage of a significant increase in specific power.

Keywords: Gas turbine, Combined cycle, Reheat
 
 

Ulisses Cortês Oliveira - ulisses@iae.cta.br
Instituto de Aeronáutica e Espaço - ASE-E/IAE/CTA
12228-904 - São José dos Campos-SP, Brazil

Abstract. This article presents the conceptual study of different designs of small pressure-fed liquid rocket engines which use storable, nontoxic propellants.  The described configurations could serve for main propulsion of upper-stages or altitude control systems of rockets and launch vehicles.  The analysis intends to be a preliminary discussion of alternative designs of upper-stage propulsion systems and reaction control systems of Brazilian rockets and launch vehicles.  They could be taken as initial points for capacitation in the field of liquid propulsion.  The study initiates with monopropellant systems based on the catalytic decomposition of hydrogen peroxide aqueous solution, which could be specially adequate to use as roll control system of VLS-1 vehicle.  All other analyzed conceptions are bipropellant systems whose oxidizer is hydrogen peroxide solution, and the fuel is either kerosene, ethanol, or liquefied propane.  The accomplished comparisons are basically of qualitative nature, although a simple quantitative analysis of the principal influences of propellant selection of the system performance had been done.

Keywords: Pressure-fed propulsion system, Rocket engine design, Reaction control system, Conceptual study, Preliminary design.
 
 

José F. C. Monteiro - monteiro@asap.iae.cta.br
João R. Barbosa - barbosa@mec.ita.cta.br
Instituto Tecnológico de Aeronáutica, Departamento de Energia
12.228-901 São José dos Campos, SPPaper S24P05

A study of numerical methods for the simulation of internal combustion engines is presented. Functional blocks, representing each component of the engine, can be combined to simulate the engine. A model was selected for each component. The engine simulation is carried out connecting the functional blocks. The inviscid conservation equations coupled with loss models where solved using a C++ computer program. Engine performance simulation is shown and results compared with published data.

Keywords: Simulation, performance, piston engine, internal combustion engine
 
 

Ulisses Cortês Oliveira - ulisses@iae.cta.br
Instituto de Aeronáutica e Espaço - ASE-E/IAE/CTA
12228-904 - São José dos Campos-SP, Brazil

Abstract. This paper presents a discussion about the adequate propellant selection for pressure-fed propulsion systems for use in launch vehicles.  The type and the proportion of the components in a bipropellant combination affects the main subsystems of the vehicle.  Therefore, its choice depends on the particular application of the propulsion system, and must be made early during the system requirement phase.  The study approaches the more relevant aspects of the problem, and the resulting information serves as a first screening of candidate propellants to be used in detailed trade-off studies.  The main conclusion is that the proper choice of nontoxic, storable, and high density-impulse propellants could produce reliable vehicles and harmless operations to personnel and environment, in addition to lower pre-operational and recurrent costs.

Keywords: Rocket propellants, Propulsion systems, Pressure-fed engine, Rocket engines, Launch vehicle design.
 
 

Rodolfo S. Collares - collares@mec.ita.cta.br
João R. Barbosa - barbosa@mec.ita.cta.br Paper S24P08
Instituto Tecnológico de Aeronáutica, Departamento de Energia
12.228-901 São José dos Campos - SP

José R. Parizi-Negrão - parizi@embraer.com.br
Embraer - Empresa Brasileira de Aeronáutica, Ensaio em Vôo.
12.228-901 São José dos Campos - SP

Flight tests for determination of the propulsion system net thrust are of utmost im-portance because the aircraft carrying capacity is dependent on the calculated thrust. Rela-tive uncertainty of 2% or more can undermine the profitability of the aircraft. Therefore, one must determine the actual propulsion system thrust with the least uncertainty possible. Pro-pulsion systems in the range of 75 kN may be underestimated, say 1%, causing 2 passengers less in the payload list. This work sets forth to define an appropriate uncertainty analysis of the measurements taken during the flight tests, aiming at a pre-defined uncertainty. Although the approach in this work is the thrust and its uncertainty calculation from flight test data, the  procedure is applicable to other measurements, in the laboratory or elsewhere. Indication of how to get the information needed for the calculations is given.

Keywords: Uncertainty, IFTD, Thrust, Gas turbine, Performance