**Author details**

pressure, Mach number and density are shown in the figure. From the results it is observed that at a back pressure of 80 kPa in the scramjet isolator, enhancement in pressure is affected due to the presence of the normal or oblique shock waves. Whereas in the case of 90 kPa back pressure, pressure rise is noted far away from the shock wave train due to the intermixing of the disorganized streamlines developed by the shock wave train. Additionally, when compared to downstream mixing region additional enhancement in the static pressure is observed due to the development of upstream shock wave train. For an adverse pressure of 100 kPa, the pressure drops in a given length due to fanno flow is much higher when compared to the increase in pressure due to intermixing and also the peak pressure is observed

*Mach number and pressure variation along the mid-plane with different back pressure at a uniform cross-*

*Numerical and Experimental Studies on Combustion Engines and Vehicles*

From **Figure 12**, it is observed that the static pressure along the axis of the isolator is observed to increase substantially. Also, with different back pressure investigated it is observed that the static pressure distribution does not get

influenced significantly because of the Mach wave train in the shock wave region of

The present analysis is focused on the significance of diverging angles and the effect of adverse pressure gradient on the behavior of the shock wave train is analyzed using the simulation. An identical flow inlet is considered at the inception point of the scramjet isolator for different diverging angles, i.e., 0, 0.5, 1 and 1.5° followed by different back pressure, i.e., 80, 90 and 100 kPa have been investigated. The following has been observed. It is observed that the shock wave train has moved near to the leading edge of the isolator with an increase in the divergent angle. At a divergent angle of 1.5°, as the flow gets separated the strong expansion wave is generated leading to the negative pressure drop at the inception of the shock wave train. When compared to the divergent angles of 1 and 1.5° in the scramjet isolator, the divergent angle of 0° with constant isolator area supports better back pressure. With an increase in adverse pressure gradient, because of the intense turbulent combustion, the shock wave train developed should expand along the length and also moves towards the leading edge of the isolator leading to rapid rise in the pressure so that the pressure at the inlet of the domain can match the enhanced negative pressure. A strong separation region occurs because of the

followed by the sequential reduction in pressure.

interaction between shock wave and boundary layer.

the isolators.

**12**

**Figure 12.**

*sectional area.*

**4. Discussions**

Santhosh Kumar Gugulothu<sup>1</sup> \*, B. Bhaskar<sup>2</sup> and V.V. Phani Babu<sup>3</sup>

1 Department of Mechanical Engineering, National Institute of Technology, Andhra Pradesh, India

2 Department of Mechanical Engineering, GITAM School of Technology, Hyderabad, India

3 Department of Mechanical Engineering, MLR Institute of Technology, Hyderabad, India

\*Address all correspondence to: santoshgk1988@gmail.com

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