Session: IMECE Undergraduate Research and Design Exposition

Paper Number: 113826

113826 - Hypersonic Heat Transfer Correlations 

Heat transfer is essential as the flight velocity of aircraft increases. As the power and speed of the vehicles increase, so does the friction which is converted into heat by the internal drag within the boundary layer. At high speeds, gas molecules around the vehicle are heated to very high temperatures, causing significant thermal loads on the surface. These high temperatures can cause significant thermal loads on the vehicle's surface, leading to material degradation, thermal stresses, and even failure of critical components. 

In hypersonic flows, correlations in heat transfer play a crucial role in determining the heat transfer rates and temperatures experienced by the vehicle's surface. Heat transfer correlations are used to predict the heat flux on the surface, which are essential for designing thermal protection systems to prevent overheating and structural failure of the vehicle. Accurate predictions of heat transfer rates are essential for designing hypersonic vehicles that can withstand the extreme thermal conditions. As the space shuttle flight re-entry envelope is a highly active area for the use of hypersonic vehicles, it is important to know the accuracy of these correlations in this region. 

Numerous calculations and experiments have been conducted to determine the convective heat transfer in boundary layer flow along simple shape surfaces. It is pertinent that these correlations are accurate. However, experimental testing can be costly and time-consuming. Hypersonic flow modelling has been heavily relied on to evaluate flow fields. For example, Chapman developed heat transfer correlations on sharp cones [1].

In this study, computational fluid dynamics simulations are used to evaluate heat transfer on cones, flat plates, and stagnation points in the space shuttle flight re-entry envelope in order to compare the data to heat transfer correlations. ANSYS Fluent is used to run the simulations to gather numerical data for the comparisons. Scripting was employed for efficiency to encompass the extensive computations and correlations in the flight envelope for each vehicle. 

 

Figure 1 illustrates the Chapman heat transfer correlation for sharp cones. This equation solves for the heat transfer rate. In the study, this equation is compared with the numerical heat transfer simulation data. The formula requires the cone angle, fight velocity, air viscosity, Prandtl number, specific gas constant, and air density. The same values will be utilized in the numerical simulation for accurate comparison. 

 

 

Table 1: Initial Flight Conditions

Mach Number

1-30

Altitude

25 - 300 (km)

Cases

350

 

Table one describes the region of comparison for the heat transfer correlations. Several different flight conditions will be tested utilizing ANSYS Fluent. The flight conditions will range from Mach 1-30 and an altitude of 25 to 300 km. The corresponding pressure, temperature, and Mach number will be calculated. Scripting was employed to set up the conditions for every case for efficiency.

Future work for this study will be to simulate more sharp cones, flat plate, and stagnation point models and compare the results to heat transfer correlations as a parametric analysis study. This requires forming a variety of cases to evaluate the heat transfer rate at different points in the space shuttle flight reentry region.

Presenting Author: Jayson Johnson Howard University

Presenting Author Biography: Jayson Johnson is an undergraduate student in the Department of Mechanical Engineering an is also a Karsh STEM Scholar at Howard University

Authors:

Sonya Smith Howard University
Jayson Johnson Howard University
Chavonne Bowen Howard University