Numerical Design Investigation of a Hydro-Mechanical Pulsator for Rocket Motor Injector Dynamics Research

Abstract

Understanding injector dynamics in the presence of strong pressure pulsations in Liquid Fueled Rocket Engines (LFRE) is important due to its strong association with the combustion instability phenomena. Lack of generators of strong periodical pulsations, particularly in the high frequency range, is problematic. To overcome this deficiency, a hydro-mechanical pulsator has been built to generate controlled periodic pressure oscillation, which simulates pressure pulsations in the feed lines of rocket motor injector systems. The present numerical analysis effort utilizes the unsteady Reynolds Averaged Navier-Stokes (URANS) approach, to model the pulsating turbulent flow inside the hydro-mechanical pulsator as a preliminary design study to estimate optimum operating conditions for the proposed experimental study. Numerical results obtained from the study using sliding/deforming grids coupled with a two-layer low-Reynolds number RNG k-ε model indicated that the form of pulsation could be controlled based on the geometry of the orifices of the rotating valve in order to define its main parameters, and in the determination of the optimum geometry for obtaining a sinusoidal harmonic response. The results of the computations to evaluate the effect of varying mass flow rates to examine the influence of change in amplitude and phase characteristics of standard injectors on the boundaries, frequencies and amplitude of high frequency combustion instability are presented in the paper.

Numerical Modelling of Cavitation: Validation and Parametric Studies

“…The understanding of the internal flow dynamics phenomena occurring in an injector is important due to their strong association with the atomisation process and consequently with the combustion process (Balasubramanyam et al, 2010). However, observing the flow in diesel injectors is very difficult as they are characterised by high pressure injections through very small nozzles with diameters of around 100 microns or less.…”

Numerical Study of The Effect of Wall Injection on The Cavitation Phenomenon In Diesel Injector

“…If the spray of fuel is in such a way that finer particles of fuel are formed, the combustion reaction will be speeded up, motor torque and efficiency will improve, and pollutants in exhaust emission will be reduced. Hence, it is very important to carry out research in order to better understand the flow dynamics inside the injector and the behavior of spray jet (Balasubramanyam et al, 2010). One of the most important parts of diesel engines is the injector nozzle.…”