wordpress get 10 posts of each custom post type

1function delete_front_page_query_results() {
2    delete_transient('post_data');
3
4    $query_cpt1 = array (
5            'posts_per_page'   => 3,
6            'post_type' => 'cpt1'
7            );
8    $query_cpt2 = array (
9            'posts_per_page'   => 3,
10            'post_type' => 'cpt2'
11            );
12    $query_cpt3 = array (
13            'posts_per_page'   => 3,
14            'post_type' => 'cpt3'
15            );
16    $query_cpt4 = array (
17            'posts_per_page'   => 3,
18            'post_type' => 'cpt4'
19            );
20    $query_cpt5 = array (
21            'posts_per_page'   => 3,
22            'post_type' => 'cpt5'
23            );
24
25    $query_results[] = get_posts($query_cpt1);
26    $query_results[] = get_posts($query_cpt2);
27    $query_results[] = get_posts($query_cpt3);
28    $query_results[] = get_posts($query_cpt4);
29    $query_results[] = get_posts($query_cpt5);
30
31    //flattening three dimentional array to two dimensonal array
32    $flatten_array =array();
33    foreach ($query_results as $data) {
34            foreach($data as $flatten_data) {
35                 $flatten_array[] = $flatten_data;
36            }
37    }
38
39    function cpt_array_sort($a, $b) {
40            return strtotime($b->post_date) - strtotime($a->post_date);
41    }
42    usort($flatten_array, 'cpt_array_sort');
43
44    //setting transient with the array
45    set_transient ( 'post_data', $flatten_array, 365*24*60*60);
46}
47add_action('publish_post', 'delete_front_page_query_results);
48