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Book ChapterDOI

Numerical Analysis on Effect of Radiation in Laboratory-Scale Hybrid Rocket Motors

01 Nov 2019-pp 717-732
TL;DR: In this paper, the effect of radiative heat transfer on the performance of a laboratory-scale hybrid rocket motor was investigated numerically using the discrete ordinates method with S6 approximation.
Abstract: In this work, the effect of radiative heat transfer in the performance of a laboratory-scale hybrid rocket motor is investigated numerically. The radiative transport equation was included in the numerical model and was solved using the discrete ordinates method with S6 approximation. In the hybrid rocket motor with radiation model, the radiative heat flux is small compared to other heat fluxes, but the change in net flux due to inclusion of radiative heat flux corresponds to the change in the surface temperature and regression rate in the motor. The net heat flux into the fuel surface increased marginally at the beginning of the motor and decreased downstream in the motor when compared with the model without radiative heat transfer. The temperature and burn rate profiles also follow a similar trend in accordance with net heat flux.
References
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Proceedings ArticleDOI
15 Jan 1996
TL;DR: In this article, computational fluid dynamic analyses of the Navier-Stokes equations coupled with solid-phase pyrolysis, gas-phase combustion, turbulence and radiation are performed to study hybrid rocket combustor flowfields.
Abstract: Computational fluid dynamic analyses of the Navier-Stokes equations coupled with solid-phase pyrolysis, gas-phase combustion, turbulence and radiation are performed to study hybrid rocket combustor flowfields. The computational study is closely coordinated with a companion experimental program using a planar slab burner configuration with HTPB as fuel and gaseous oxygen. The major objective of this computational study is to extend the results of the labscale tests to a full-scale configuration. Toward mis end, experimental data of the fuel regression rates and surface temperatures obtained from the subscale tests are used to verify the computational model. The computational model is then applied to a full-scale axisymmetric configuration to see how the results scale with size and geometric configuration. The model predictions indicate that fuel surface regression rates are considerably impacted by both the size and geometry of the configuration. The results thus demonstrate that detailed CFD analyses can play a useful role in the understanding of hybrid combustion and in the design of hybrid combustors. The model predictions indicate that the scaling from the planar slab configuration to the axisymmetric is quite complex.

40 citations

Journal ArticleDOI
TL;DR: In this work, single-port, cylindrical grain laboratory-scale hybrid rocket motors are numerically simulated to study the effect of diaphragms.
Abstract: In this work, single-port, cylindrical grain laboratory-scale hybrid rocket motors are numerically simulated to study the effect of diaphragms. The effect of single and multiple diaphragms is investigated by varying diaphragm height, its axial location (for a single diaphragm), and spacing (for multiple diaphragms) at selected inlet GOX. A single diaphragm increases the local regression rate and its influence is prominent only in the region immediate downstream. Therefore, a tangible increment in average regression rate with a single diaphragm can only be realized for motors with small L/D( 10), use of multiple diaphragms are required to increase the regression rate and combustion effici...

39 citations

Proceedings ArticleDOI
12 Jul 1995
TL;DR: In this paper, an experimental investigation was conducted on fundamental processes involved in hybrid rocket combustion using a high-pressure, two-dimensional hybrid motor, and the results indicated that the surface temperature of the burning fuel was around 1000 K depending upon axial locations and operating conditions.
Abstract: Using a high-pressure, two-dimensional hybrid motor, an experimental investigation was conducted on fundamental processes involved in hybrid rocket combustion. HTPB (Hydroxyl-terminated Polybutadiene) fuel cross-linked with diisocyanate was burned with GOX under various operating conditions. Large-amplitude pressure oscillations were encountered in earlier test runs. After identifying the source of instability and decoupling the GOX feed-line system and combustion chamber, the pressure oscillations were drastically reduced from +/-20% of the localized mean pressure to an acceptable range of +/-1.5% Embedded fine-wire thermocouples indicated that the surface temperature of the burning fuel was around 1000 K depending upon axial locations and operating conditions. Also, except near the leading-edge region, the subsurface thermal wave profiles in the upstream locations are thicker than those in the downstream locations since the solid-fuel regression rate, in general, increases with distance along the fuel slab. The recovered solid fuel slabs in the laminar portion of the boundary layer exhibited smooth surfaces, indicating the existence of a liquid melt layer on the burning fuel surface in the upstream region. After the transition section, which displayed distinct transverse striations, the surface roughness pattern became quite random and very pronounced in the downstream turbulent boundary-layer region. Both real-time X-ray radiography and ultrasonic pulse-echo techniques were used to determine the instantaneous web thickness burned and instantaneous solid-fuel regression rates over certain portions of the fuel slabs. Globally averaged and axially dependent but time-averaged regression rates were also obtained and presented.

29 citations