3 Day Open Conference

Dynamic ICP® pressure sensors for detection of combustion instability and high intensity acoustics in liquid, cryogenic, and solid rocket motor research
Wednesday 19th November 2008
11.20 - 11.40
Auditorium 1

Rocket motor combustion instability, commonly referred to screeching, is damaging, and often difficult hard to eliminate. Caused by acoustic resonances in the combustion chamber, it can lead to unstable resonant screeching that commonly leads to catastrophic failure by a break down of the thermal insulating boundary layer. It is rather difficult to model this phenomenon during rocket motor design.  Dynamic ICP® pressure sensors are available to assist design engineers in studying combustion instability.  The piezoelectric pressure sensors are rugged, hermetically sealed, and structured with acceleration-compensated quartz sensing elements that detect rapid pressure transients, pulsations, turbulence, noise, and spikes.  

Water-cooled, Helium Bleed Series 122, 123 and 124, are designed expressly for measurement of combustion instability in rocket motors.  They are ideal for rocket motor testing to verify the amplitude and mode of screeching instabilities during motor firings in addition to the amplitude and frequency of the pressure oscillations.  They may also be used to determine the time required for complete combustion of solid rocket motor fuel as a function of pressure and oxidizer concentrations.

Cryogenic Series 102 are ideal for evaluation of low frequency oscillation, or chugging of fuel and oxidizer pump inlets, which can cause cyclic variation in thrust, and can damage payloads or the rocket. They are also useful for studying buzzing of liquid rocket injectors.

These devices monitor dynamic pressures while subjected to high static background pressure.  ICP® output features on-board electronics to provide conditioned output signal and ease of use. Many physical configurations are available with various Aerospace Standard fitting sizes.  Helium bleed protects the quartz sensor from intense heat, and also increases frequency response of the recess gas passage. Water cooling allows for maximum thermal stability and extends sensor operating temperature.  This paper will discuss their effectiveness in helping the design engineer model rocket motor combustion instabilities.

About the Speaker(s):

Bob Metz
Lead Product Manager
PCB Piezotronics