Burning rate propellants

R. C. Strittmater, E. M. Wineholt, and M. E. Holmes, The Sensitivity of Double Base Propellant Burning Rate to Initial Temperature, MR-2593, BRL, Aberdeen, Md., 1976. 

Correlation of Threshold Pressure with Propellant Burning Rate. P 449... 

Oxide Surface Area In Propellant Burn Rate Enhancement (First Step Toward Modelling) , Rockwell Inti Corp, Rocket dyne Div, Tex,... 

Fig 17 Correlation of threshold pressure with propellant burning rate (5- x 40-inch rocket motor)... 

With these goals in mind, several investigators have undertaken to set down quantitative expressions which will predict propellant burning rates in terms of the chemical and physical properties of the individual propellant constituents and the characteristics of the ingredient interactions. As in the case of ignition, the basic approach taken in these studies must consider the different types of propellants currently in use and must make allowances for their differences. In the initial combustion studies, the effort was primarily concerned with the development of combustion models for double-base propellants. With the advent of the heterogeneous composite propellants, these studies were redirected to the consideration of the additional mixing effects. 

The effect on the propellant burning rate of gas flow parallel to the propellant surface has received considerable experimental and theoretical attention. These studies have generally shown that there is little effect of gas flow parallel to the propellant surface, provided the flow rate is below a certain critical level. However, once this critical value has been exceeded, the burning rate increases with increasing mass flow rate. 

When the propellant burning rate is espressed by Eq. (5b), the parameter p /e can be considered as the transient sensitivity of the burning rate to pressure. This parameter depends on the transient combustion characteristics, and its evaluation depends on the particular model of the combustion process. Thus, the acoustic admittance provides the link between experimental observation and theoretical prediction. 

Friedly (F4) expanded the theoretical analysis of Hart and McClure and included second-order perturbation terms. His analysis shows that the linear response of the combustion zone (i.e., the acoustic admittance) is not sign-ficantly altered by the incorporation of second-order perturbation terms. However, the second-order perturbation terms predict changes in the propellant burning rate (i.e., transition from the linear to nonlinear behavior) consistent with experimental observation. The analysis including second-order terms also shows that second-harmonic frequency oscillations of the combustion chamber can become important. 

In general, the internal pressure in a gun barrel exceeds 200 MPa, and the pressure exponent, n, of the propellant burning rate given by Eq. (1.80) is 1. When n = 1, the burning rate of a gun propellant is represented by... 

Caveny, L. H., and Click, R. L, The Influence of Embedded Metal Fibers on Solid Propellant Burning Rate, Journal of Spacecraft and Rockets, Vol. 4, No. 1,... 

Since the burning rate of a propellant is dependent on the burning pressure, the mass balance between the mass generation rate in the chamber and the mass discharge rate from the nozzle is determined by the pressure. In addition, the propellant burning rate in a rocket motor is affected by various phenomena that influence the mass balance relationship. Fig. 14.4 shows typical combustion phenomena encountered in a rocket motor, from pressure build-up by ignition to pressure decay upon completion of the combustion. 

Although dewetting has been and currently is the subject of much discussion, its implications with respect to motor performance are not clear. In some cases the propellant burn rate appears to depend upon... 

Composite Propellant Burning Rate Behavior. Figure 2 shows typical composite propellant burning rate data obtained to date. Generally, around 100 atm. the pressure exponent (n in the empirical equation r = apn) is about 0.3, and near 1 atm. it lies between 0.6 and 0.9, depending on the propellant type. Such burning rate data are best correlated by the equation ... 

Low-frequency oscillation in a rocket motor depends on the pressure exponent of propellant burning rate and the free volume of the chamber. [ -7] when a double-base propellant composed of nc(0 510), ng( - 55), and dep(0.120), with pbsa(0.015) as a platonizing catalyst, bums in a strand burner, the burning rate characteristicsmay be divided into four zones, as shown in Fig. 13.14. The pressure exponent varies between the pressure zones n = 0.44 in zone I above 3.7 MPa, n= 1.1 in zone II between 3.7 MPa and 2.1 MPa, n = 0.77 in zone III between 2.1 MPa and 1.1 MPa, and n = 1.4 in zone IV below 1.1 MPa. 

Mench, M.M., Yeh, C.L., and Kuo, K.K. (1998) Propellant burning rate enhancement and thermal behaviour of ultra fine A1 powders (ALEX). Proc. 29th Inti. Ann. Conf. ICT, Karlsruhe, Germany, June 30-July 03, 1998, pp. 30/1-30/15. 

Saber M. Summerfield, Propellant Burning Rate and Combustion Uniformity Identified by Ultrasonic Acoustic Emission , AMS Rept 1302, Final Rept, Contract DAAA21-74-C-0332 (Jan 1976) 16) W.A. Bell, J.I. Craig W.C. Strahle,... 

Measurement of Solid Propellant Burning Rate (Refs 1, 2 4)... 

Fig 3 Gamma-Ray Feedback Transducer System for Propellant Burning Rate Measurement... 

Burick P.Y. Ho, Techniques for the Continuous Measurement of Solid Propellant Burning Rates , Report No F-66-3, JPC 421, Jet Propulsion Center, Purdue University (1966)... 

Test the means of the composite propellant burning rates at 70 [bar]. 

Analysis of variance has also been applied in testing three factors of composite rocket propellant burning rate in Crawford s-bomb at lOObar and 20 °C temperature. The analyzed factors are contents of fine fraction in bimodal oxidizer mixture (C) contents ratio of oxidizer mixture-aluminum powder (B) and contents of burning rate catalyst (A). The obtained burning rate values are given in the table in mm/s ... 

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