Performance analysis of injectors for a hybrid propulsion system

  • Shirley M. Pedreira
  • Rita C. L. Dutra
  • José I. S. Oliveira
  • Rene F. B. Gonçalves
  • Roberta J. Rocha
  • José A. F. F. Rocco
Technical Paper


This paper presents a study about injectors, where the radial injector was evaluated. This type of injector was chosen because only a small amount of information on it was found. Thus, the radial injector will be compared with other two types of injectors, the orifice plate and the swirl, in terms of parameters, such as discharge coefficient (Cd), regression rate r, and specific impulse (Isp). In respect of the regression rate, the values appeared increasingly with the test pressure and, consequently, with the injection pressure. Thus, each injector model responded in the same way as for the regression rate behavior; however, the same behavior was not observed in relation to the specific impulse.


Hybrid propulsion Injectors Paraffin 

List of symbols


Empirical constant of fuel provided in pair with ‘n


Base area


Injection area


Characteristic velocity


Discharge coefficient


External grain diameter


Internal grain diameter


Average grain diameter


Time derivative


The thrust force


Gravity acceleration


Oxidizer mass velocity


Specific impulse


Total impulse


Grain length


Mass flow in the injection area


Mass flow in kg/s


Total effective propellant mass


Mass flow on web thickness


Exponent of G0 provided in pair with ‘a


Fuel flow rate on web thickness


Regression rate or burning time

\(t_{\text{b}} ,t\)

Burn time, time


Total weight flow rate of propellants

\(\Delta P\)

Charge loss in the injector


Fuel density or specific mass


Oxidizer density



To CAPES (Commission for the Improvement of Higher Education Personnel) which provides postdoctoral fellowship to first author and other fellowship by PVNS (National Senior Visiting Professor Program) to last author.


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Copyright information

© The Brazilian Society of Mechanical Sciences and Engineering 2019

Authors and Affiliations

  • Shirley M. Pedreira
    • 1
  • Rita C. L. Dutra
    • 1
  • José I. S. Oliveira
    • 2
  • Rene F. B. Gonçalves
    • 1
  • Roberta J. Rocha
    • 3
  • José A. F. F. Rocco
    • 1
  1. 1.Aeronautics Institute of TechnologySão José dos Campos, São PauloBrazil
  2. 2.Institute of Aeronautics and SpaceSão José dos Campos, São PauloBrazil
  3. 3.AvibrásSão José dos Campos, São PauloBrazil

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