No abstract

No abstract

The effect of ablation on the discharge characteristics of solid rocket engines with submerged nozzles is examined. State-of-the-art computational fluid dynamics software package ANSYS Fluent is employed for simulation. The ablation is considered from the standpoint of the effect caused by uniform blowing of degradation products on the boundary layer developing over the entrance length of the submerged nozzle. Different masses of injected substance are considered. The impact of injection on velocity profiles is estimated. The discharge coefficient is affected by the non-isothermal boundary layer when degraded thermal protection material is injected and chemical reactions are neglected. The effect of injection on the profiles of velocity and temperature, and hence, on discharge characteristics is revealed.

Представлены результаты исследования возможности применения RANS моделей турбулентности для описания структуры потока в измерительном трубопроводе со стандартной диафрагмой и расчета ко-эффициента расхода с точностью, регламентированной стандартом. Показано влияние параметров сет-ки на точность расчета и сформированы рекомендации по сгущению сетки в пристеночных областях. Представлены зависимости протяженности отрывных зон от числа Рейнольдса. Установлены диапа-зоны по числу Рейнольдса применимости различных RANS моделей турбулентности для определения коэффициента расхода с погрешностью, удовлетворяющей требованиям стандарта.Ключевые слова: модель турбулентности, коэффициент расхода, диафрагма, вычислительная гидроди-намика, структура потока.

Modern methods of computational fluid dynamics have been used to study flows with mass supply in axisymmetric channels of solid-propellant rocket motor charges. The studies were carried out with the aim of increasing the accuracy of predicting the intraballistic parameters for performing engineering calculations. The analysis of changes in intraballistic characteristics in the flow part of the channel charge in the classical and nozzleless solid propellant rocket motors is carried out for different rates of mass supply from the combustion surface. For an isobaric combustion chamber, a characteristic velocity profile is shown along a tubular charge path and a charge with sudden expansion. It is shown that for a steady cosine profile of axial velocity after sudden expansion of the channel, a length of more than three gauges is required. For a high-speed combustion chamber, a comparison of the axial velocity profile is carried out depending on the flow velocity under different conditions of mass supply. The tendency of the influence of flow velocity on the character of the profile is noted. It is shown that at a Mach number over 0.5, an increase in the mass flow rate from the combustion surface provides a less filled velocity profile tending to cosine. The differences between the pressure losses in the flow passage of the channel charge, calculated in the axisymmetric approximation, and the losses determined using gas-dynamic functions, are shown. An increase of the mass flow rate in the charge channel of a nozzleless solid-propellant rocket motor leads to a decrease in pressure losses at Mach number over 0.8.